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sh-posix(1)							   sh-posix(1)

NAME
       sh-posix:  sh, rsh - standard and restricted POSIX.2-conformant command
       shells

SYNOPSIS
       option]... string] [arg]...

       option]... string] [arg]...

   Remarks
       This shell is intended to conform to the	 shell	specification  of  the
       POSIX.2	standards.   Check any standards conformance documents shipped
       with your system for information on the conformance of  this  shell  to
       any other standards.

   List of Subheadings in DESCRIPTION
       Shell Invocation	   Tilde Substitution	     Environment
       Options		   Command Substitution	     Functions
       rsh Restrictions	   Parameter Substitution    Jobs
       Definitions	   Blank Interpretation	     Signals
       Commands		   File Name Generation	     Execution
       Simple Commands	   Quoting		     Command Reentry
       Compound Commands   Arithmetic Evaluation     Command Line Editing
       Special Commands	   Prompting		     emacs/gmacs Editing Mode
       Comments		   Conditional Expressions   vi Editing Mode
       Aliasing		   Input/Output

DESCRIPTION
       is  a  command  programming language that executes commands read from a
       terminal or a file.

       is a restricted version of See the subsection below.

   Shell Invocation
       If the shell is invoked by an system call and the  first	 character  of
       argument	 zero  (shell  parameter  is dash the shell is assumed to be a
       login shell and commands are read first from then from  either  in  the
       current	directory  or if either file exists, and finally from the file
       named by performing parameter substitution on the value of the environ‐
       ment parameter if the file exists.  If the option is not present and an
       arg is, a path search is performed on the first arg  to	determine  the
       name  of	 the script to execute.	 When running with arg, the script arg
       must have read permission and any and settings will be  ignored.	  Com‐
       mands are read as described below.

       Shell  output,  except for the output of some of the commands listed in
       the subsection, is written to standard error (file descriptor 2).

   Options
       The following options are interpreted by the shell when it is invoked.

       Read commands from
		  string.

       If	  is present or if the shell input and output are attached  to
		  a  terminal  (as  reported  by the shell is interactive.  In
		  this case is ignored and is caught and ignored (so  that  is
		  interruptible).  In all cases, is ignored by the shell.  See
		  signal(5).

       The shell is a restricted shell.

       If	  is present or if no arguments remain, commands are read from
		  the standard input.

       The  remaining  options and operands are described under the command in
       the subsection.

   rsh Restrictions
       is used to set up login names and execution environments where capabil‐
       ities  are  more	 controlled  than  those  of  the standard shell.  The
       actions of are identical to those of except that the following are for‐
       bidden:

	 ·  Changing directory (see the special command and cd(1))
	 ·  Setting the value of or
	 ·  Specifying path or command names containing
	 ·  Redirecting output and

       The  restrictions  above	 are  enforced	after the and files are inter‐
       preted.

       When a command to be executed is found to be a shell procedure, invokes
       to  execute  it.	  Thus, the end-user is provided with shell procedures
       accessible to the  full	power  of  the	standard  shell,  while	 being
       restricted to a limited menu of commands.  This scheme assumes that the
       end-user does not have write and execute permissions in the same direc‐
       tory.

       These  rules  effectively  give the writer of the file complete control
       over user actions, by performing guaranteed set-up actions and  leaving
       the  user  in  an  appropriate directory (probably not the login direc‐
       tory).

       The system administrator often sets up a directory of commands (usually
       that can be safely invoked by HP-UX systems provide a restricted editor
       (see ed(1)), suitable for restricted users.

   Definitions
       One of the following characters:

       A tab or a space.

       A sequence of letters, digits, or underscores
			   starting with a letter or underscore.   Identifiers
			   are used as names for and

       A sequence of	   separated by one or more nonquoted

       A sequence of characters in the syntax of the shell language.
			   The	shell  reads  each command and carries out the
			   desired action, either directly or by invoking sep‐
			   arate utilities.

       A command that is carried out by the shell
			   without  creating  a	 separate process.  Except for
			   documented side effects, most special commands  can
			   be implemented as separate utilities.

       Comment delimiter.  A  word beginning with and all following characters
			   up to a newline are ignored.

       An		   a decimal number, or one of the characters and  See
			   the subsection.

       A		   that can be assigned a value.  See the subsection.

       A

       A		   that	 is  known outside the local shell, usually by
			   means of the special command.

   Commands
       A command can be a simple command that executes an executable  file,  a
       special	command	 that executes within the shell, or a compound command
       that provides flow of control for groups of simple, special,  and  com‐
       pound commands.

   Simple Commands
       A  simple  command  is  a sequence of blank-separated words that may be
       preceded by a parameter assignment list.	 (See  the  subsection).   The
       first word specifies the name of the command to be executed.  Except as
       specified below, the remaining words are passed	as  arguments  to  the
       invoked command.	 The command name is passed as argument (see exec(2)).
       The value of a simple command is its exit status if it terminates  nor‐
       mally,  or  if  it  terminates  abnormally (see signal(5) for a list of
       errorstatus values).

       A is a sequence of one or more commands separated by a bar and  option‐
       ally  preceded  by an exclamation mark The standard output of each com‐
       mand but the last is connected by a pipe (see pipe(2)) to the  standard
       input  of the next command.  Each command is run as a separate process;
       the shell waits for the last command to terminate.  If does not precede
       the pipeline, the exit status of the pipeline is the exit status of the
       last command in the pipeline.  Otherwise, the exit status of the	 pipe‐
       line  is the logical negation of the exit status of the last command in
       the pipeline.

       A list is a sequence of one or  more  pipelines	separated  by  or  and
       optionally terminated by or

	      Causes sequential execution of the preceding pipeline.
		     An	 arbitrary  number  of	newlines can appear in a list,
		     instead of semicolons, to delimit commands.

	      Causes asynchronous execution of the preceding pipeline
		     (that is, the shell does not wait for  that  pipeline  to
		     finish).

	      Causes  asynchronous execution of the preceding command or pipe‐
	      line
		     with a two-way pipe established to the parent shell.  The
		     standard  input  and output of the spawned command can be
		     written to and read from by the parent  shell  using  the
		     option of the special commands and

	      Causes the
		     list  following  it  to be executed only if the preceding
		     pipeline returns a zero value.

	      Causes the
		     list following it to be executed only  if	the  preceding
		     pipeline returns a nonzero value.

       Of  these  five symbols, and have equal precedence, which is lower than
       that of and The symbols and also have equal precedence.

   Compound Commands
       Unless otherwise stated, the value returned by a	 compound  command  is
       that  of the last simple command executed in the compound command.  The
       segment separator can be replaced by one or more newlines.

       The following keywords are recognized only as the first word of a  com‐
       mand and when not quoted:

       A compound command is one of the following.

	      Execute  the list associated with the first pattern that matches
	      word.  The form of the patterns is identical to  that  used  for
	      file  name generation (see the subsection).  The case terminator
	      cannot be replaced by newlines.

	      Set identifier to each word in sequence and  execute  the	 list.
	      If  word ...   is omitted, set identifier to each set positional
	      parameter instead.  See the  subsection.	 Execution  ends  when
	      there are no more positional parameters or words in the list.

	      Define  a function named by identifier.  A function is called by
	      executing its identifier as a command.  The body of the function
	      is the list of commands between and See the subsection.

	      Execute  the  list  and, if its exit status is zero, execute the
	      first list.  Otherwise, execute the list (if any)	 and,  if  its
	      exit  status is zero, execute the next list.  Failing that, exe‐
	      cute the list (if any).  If no list or list is executed, returns
	      a zero exit status.

	      Print  the  set  of words on standard error (file descriptor 2),
	      each preceded by a number.  If word ...  is omitted,  print  the
	      positional  parameters  instead (see the subsection).  Print the
	      prompt and read a line from standard input into the parameter If
	      this line consists of the number of one of the listed words, set
	      identifier to the corresponding word, execute list,  and	repeat
	      the  prompt.   If	 the  line  is empty, print the selection list
	      again, and repeat the  prompt.   Otherwise,  set	identifier  to
	      null,  execute  list,  and  repeat  the prompt.  The select loop
	      repeats until a special command or end-of-file is encountered.

	      Execute the pipeline and print the elapsed time, the user	 time,
	      and  the	system	time on standard error.	 Note that the keyword
	      can appear anywhere in the pipeline to time the entire pipeline.
	      To time a particular command in a pipeline, see time(1).

	      Execute the list.	 If the exit status of the last command in the
	      list is nonzero, execute the list and execute  the  list	again.
	      When  the	 exit  status of the last command in the list is zero,
	      terminate the loop.  If no commands in the  list	are  executed,
	      returns a zero exit status.

	      Execute the list.	 If the exit status of the last command in the
	      list is zero, execute the list and execute the list again.  When
	      the exit status of the last command in the list is nonzero, ter‐
	      minate the loop.	If no  commands	 in  the  list	are  executed,
	      returns a nonzero exit status.

	      Execute  list  in	 a separate environment.  If two adjacent open
	      parentheses are needed for nesting, a  space  must  be  inserted
	      between them to avoid arithmetic evaluation.

	      Execute list, but not in a separate environment.	Note that is a
	      keyword and requires a trailing blank to be recognized.

	      Evaluate expression and return a zero exit status	 when  expres‐
	      sion  is	true.  See the subsection for a description of expres‐
	      sion.  Note that and are keywords	 and  require  blanks  between
	      them and expression.

   Special Commands
       Special	commands  are  simple  commands that are executed in the shell
       process.	 They permit input/output redirection.	Unless otherwise indi‐
       cated,  file descriptor 1 (standard output) is the default output loca‐
       tion and the exit status, when there are no syntax errors, is zero.

       Commands that are marked with "%" are treated specially in the  follow‐
       ing ways:

	      1. Variable  assignment  lists  preceding	 the command remain in
		 effect when the command completes.
	      2. I/O redirections are processed after variable assignments.
	      3. Certain errors cause a script that contains them to abort.

       Words following commands marked with "&" that are in the	 format	 of  a
       variable	 assignment  are  expanded  with  the same rules as a variable
       assignment.  This means that tilde substitution is performed after  the
       sign and word-splitting and file-name generation are not performed.

       %
	      (colon)	 Only  expand  parameters.   A	zero  exit  status  is
	      returned.

       %
	      (period)	Read and execute commands from file and	 return.   The
	      commands	are  executed  in  the current shell environment.  The
	      search path specified by is used to find the directory  contain‐
	      ing file.	 If any arguments arg are given, they become the posi‐
	      tional parameters.  Otherwise,  the  positional  parameters  are
	      unchanged.   The exit status is the exit status of the last com‐
	      mand executed.

       &
	      With specified, define name as an alias and assign it the	 value
	      value.   A  trailing  space  in value causes the next word to be
	      checked for alias substitution.

	      With omitted, print the list of aliases in the form on  standard
	      output.

	      With name specified without print the specified alias.

	      With  set	 tracked aliases.  The value of a tracked alias is the
	      full path name corresponding to the given name.  The value of  a
	      tracked  alias becomes undefined when the value of is reset, but
	      the alias remains tracked.  With	omitted,  print	 the  list  of
	      tracked aliases in the form on standard output.

	      With  set exported aliases.  An exported alias is defined across
	      subshell environments.  With omitted, print the list of exported
	      aliases in the form on standard output.

	      Alias returns true unless a name is given for which no alias has
	      been defined.

	      See also the special command.

	      Put the specified jobs into the background.  The current job  is
	      put in the background if job is unspecified.  See the subsection
	      for a description of the format of job.  See  also  the  special
	      command.

       %
	      Exit  from  the  enclosing  or loop, if any.  If n is specified,
	      exit from n levels.

	      In the first form, change the current working directory to  arg.
	      If arg is the directory is changed to the previous directory The
	      shell parameter is the default arg.  After the the and  environ‐
	      ment variables are set to the new current directory and the for‐
	      mer directory respectively.

	      With (default), preserve logical naming when  treating  symbolic
	      links.  moves the current directory one path component closer to
	      the root directory.

	      With preserve the physical path when  treating  symbolic	links.
	      changes  the working directory to the actual parent directory of
	      the current directory.

	      The shell parameter defines the search path  for	the  directory
	      containing  arg.	Alternative directory names are separated by a
	      colon If is null or undefined, the default value is the  current
	      directory.   Note	 that  the current directory is specified by a
	      null path name, which can appear	immediately  after  the	 equal
	      sign  or	between the colon delimiters anywhere else in the path
	      list.  If arg begins with a the search path is not used.	Other‐
	      wise,  each directory in the path is searched for arg.  See also
	      cd(1).

	      The second form of substitutes the string new for the string old
	      in  the  current directory name, and tries to change to this new
	      directory.

	      Treat arg as a command, but disable function lookup on arg.  See
	      command(1) for usage and description.

       %
	      Resume  the  next	 iteration  of the enclosing or loop.  If n is
	      specified, resume at the nth enclosing loop.

	      Print arg	 on  standard  output.	 See  echo(1)  for  usage  and
	      description.  See also the special command.

       %
	      Read the arguments as input to the shell and execute the result‐
	      ing commands.  Allows parameter substitution  for	 keywords  and
	      characters that would otherwise be unrecognized in the resulting
	      commands.

       %
	      Parameter assignments remain in effect after  the	 command  com‐
	      pletes.	If  arg is given, execute the command specified by the
	      arguments in place of this shell without creating a new process.
	      Input/output   arguments	may  appear  and  affect  the  current
	      process.	If no arguments are given, modify file descriptors  as
	      prescribed  by the input/output redirection list.	 In this case,
	      any file descriptor numbers greater than 2 that are opened  with
	      this mechanism are closed when another program is invoked.

       %
	      Exit  from  the shell with the exit status specified by n.  If n
	      is omitted, the exit status is that of  the  last	 command  exe‐
	      cuted.   An  end-of-file	also  causes the shell to exit, except
	      when a shell has the option set.	(See the special command.)

	      Mark the given variable names for automatic export to the	 envi‐
	      ronment  of  subsequently executed commands.  Optionally, assign
	      values to the variables.

	      With no arguments, write the names and values  of	 all  exported
	      variables to standard output,

	      With  write  the	names  and values of all exported variables to
	      standard output, in a format with the proper use of quoting,  so
	      that  it	is suitable for re-input to the shell as commands that
	      achieve the same exporting results.

	      List, or edit and reexecute, commands previously entered	to  an
	      interactive  shell.   A  range of commands from first to last is
	      selected from the last commands  typed  at  the  terminal.   The
	      arguments first and last can be specified as a number or string.
	      A given string is used to locate the  most  recent  command.   A
	      negative number is used to offset the current command number.

	      With  list  the commands on standard output.  Without invoke the
	      editor program ename on a file containing	 these	keyboard  com‐
	      mands.   If  ename  is  not supplied, the value of the parameter
	      (default is used as the editor.  Once  editing  has  ended,  the
	      commands	(if  any)  are executed.  If last is omitted, only the
	      command specified by first is used.  If first is not  specified,
	      the  default  is	the  previous  command for editing and −16 for
	      listing.

	      With reverse the order of the commands.

	      With suppress command numbers when listing.

	      With reexecute the command without invoking an editor.

	      The argument replaces the first occurrence of string in the com‐
	      mand to be reexecuted by the string new.

	      Bring  each  job into the foreground in the order specified.  If
	      no job is specified, bring the current job into the  foreground.
	      See  the subsection for a description of the format of job.  See
	      also the special command.

	      Parse the argument list, or  the	positional  parameters	if  no
	      arguments,  for  valid  options.	 On each execution, return the
	      next option in name.  See getopts(1) for usage and description.

	      An option begins with a or a An argument not beginning  with  or
	      or  the  argument ends the options.  optstring contains the let‐
	      ters that recognizes.  If a letter is followed by a that	option
	      is  expected  to have an argument.  The options can be separated
	      from the argument by blanks.

	      For an option specified as name is set to letter.	 For an option
	      specified	 as name is set to The index of the next arg is stored
	      in The option argument, if any, is stored in If no option	 argu‐
	      ment is found, or the option found does not take an argument, is
	      unset.

	      A leading in optstring causes to store the letter of an  invalid
	      option in and to set name to for an unknown option and to when a
	      required option argument is missing.  Otherwise, prints an error
	      message.	 The  exit  status  is	nonzero when there are no more
	      options.

	      Affect the way the current shell environment remembers the loca‐
	      tions  of	 utilities.   With utility, add utility locations to a
	      list of remembered locations.  With no arguments, print the con‐
	      tents  of the list.  With forget all previously remembered util‐
	      ity locations.

	      List information about each given job, or all active jobs if job
	      is not specified.	 With list process IDs in addition to the nor‐
	      mal information.	With display only jobs that  have  stopped  or
	      exited  since  last notified.  With list only the process group.
	      See the subsection for a description of the format of job.

	      Send either signal 15 (terminate) or the specified signal to the
	      specified	 jobs or processes.  If the signal being sent is (ter‐
	      minate) or (hangup), the job or process  is  sent	 a  (continue)
	      signal when stopped.  See kill(1) for usage and description.

	      With list the signal names and numbers.

	      Evaluate	each arg as a separate arithmetic expression.  See the
	      subsection for a description of  arithmetic  expression  evalua‐
	      tion.   The exit status is 0 if the value of the last expression
	      is nonzero, and 1 otherwise.

       %
	      Replace the current shell with a new one	having	group  as  the
	      user's  group.   The  default  group  is the user's login group.
	      With also execute the user's and files.  See newgrp(1) for usage
	      and description.	Equivalent to

	      The  shell  output mechanism.  With no options or with option or
	      print the arguments on standard output as described in  echo(1).
	      See also printf(1).

	      With do not add a newline character to the output.

	      With  write  the	arguments onto the pipe of the process spawned
	      with instead of standard output.

	      With or (raw mode), ignore the escape conventions of With	 print
	      all subsequent arguments and options other than

	      With  write  the	arguments  into the history file instead of to
	      standard output.

	      With specify a one-digit file descriptor unit number n on	 which
	      the output will be placed.  The default is (standard output).

	      Print  the  name of the current working directory (equivalent to
	      With (the default), preserve the logical meaning of the  current
	      directory.   With	 preserve  the physical meaning of the current
	      directory if it is a symbolic link.  See also the	 special  com‐
	      mand, cd(1), ln(1), and pwd(1).

	      The  shell  input	 mechanism.   Read  one line (by default, from
	      standard input) and break it up into words using the  characters
	      in as separators.	 The first word is assigned to the first name,
	      the second word to the second name, and  so  on;	the  remaining
	      words  are  assigned  to	the last name.	See also read(1).  The
	      return code is unless an end-of-file is encountered.

	      With take the input line	from  the  input  pipe	of  a  process
	      spawned  by  the	shell using An end-of-file with causes cleanup
	      for this process so that another process can be spawned.

	      With (raw mode), a at the end of a line does  not	 signify  line
	      continuation.

	      With save the input as a command in the history file.

	      With specify a one-digit file descriptor unit to read from.  The
	      file descriptor can be opened with  the  special	command.   The
	      default  value of n is (standard input).	If name is omitted, is
	      used as the default name.

	      If the first argument contains a the remainder of	 the  argument
	      is used as a prompt when the shell is interactive.

	      If the given file descriptor is open for writing and is a termi‐
	      nal device, the prompt is placed on that unit.   Otherwise,  the
	      prompt is issued on file descriptor 2 (standard error).

	      Mark  the	 given names read only.	 These names cannot be changed
	      by subsequent assignment.

	      With write the names and values of all  read-only	 variables  to
	      standard	output	in  a format with the proper use of quoting so
	      that it is suitable for re-input to the shell as	commands  that
	      achieve the same attribute-setting results.

       %
	      Cause a shell function to return to the invoking script with the
	      return status specified by n.  If n is omitted, the return  sta‐
	      tus  is  that of the last command executed.  Only the low 8 bits
	      of n (decimal 0 to 255) are passed back to the  caller.	If  is
	      invoked  while  not  in  a function or a script (see the special
	      command), it has the same effect as an command.

       % option]...
	      name] [arg]...
	      Set or clear execution options or perform array assignments  All
	      options  except  and  can be supplied in a shell invocation (see
	      the section and the subsection).

	      Using instead of before an option causes the option to be turned
	      off.   These  options  can also be used when invoking the shell.
	      The current list of set single-letter options  is	 contained  in
	      the shell variable It can be examined with the command

	      The  and	options	 can be intermixed in the same command, except
	      that there can be only one or option.

	      Unless or is specified, the remaining arg arguments are assigned
	      consecutively to the positional parameters

	      The  command  with  neither  arguments  nor options displays the
	      names and values of all shell  parameters	 on  standard  output.
	      See also env(1).

	      The options are defined as follows.

	      Array assignment.
		     Unset  the	 variable  name and assign values sequentially
		     from the list arg.	 With do not unset the	variable  name
		     first.

	      Automatically export subsequently defined parameters.

	      Cause the shell to notify the user asynchronously
		     of background jobs as they are completed.	When the shell
		     notifies the user that a job has been completed,  it  can
		     remove  the job's process ID from the list of those known
		     in the current shell execution environment.

	      Prevent redirection
		     from truncating  existing	regular	 files.	  Requires  to
		     truncate a file when turned on.

	      Execute the
		     trap,  if	set,  and exit if a command has a nonzero exit
		     status, and is not part of the compound list following  a
		     or	 keyword, and is not part of an AND or OR list, and is
		     not a pipeline preceded by the reserved word.  This  mode
		     is disabled while reading profiles.

	      Disable file name generation.

	      Specify that each command whose name is an
		     identifier	 becomes  a  tracked  alias when first encoun‐
		     tered.

	      Place all parameter assignment arguments
		     (not just those that precede the command name)  into  the
		     environment for a command.

	      Run background jobs in a separate process group
		     and  print	 a  line  upon completion.  The exit status of
		     background jobs is	 reported  in  a  completion  message.
		     This  option  is  turned on automatically for interactive
		     shells.

	      Read commands and check them for syntax errors, but do not  exe‐
	      cute them.
		     The option is ignored for interactive shells.

	      Set an option  argument  from  the  following  list.  Repeat the
		     option to specify additional option arguments.

		     Same as
		     Run all background jobs at a lower priority.
		     Use a	    inline editor for command entry.
		     Same as
		     Use a	    inline editor for command entry.
		     Do not exit from the shell on end-of-file
				    (eof, as defined by default is The special
				    command must be used.
		     Same as
		     Append a trailing
				    to all directory names resulting from file
				    name generation.
		     Same as
		     Same as
		     Same as
		     Same as
		     Do not save function definitions in history file.
		     Same as
		     Same as
		     Same as
		     Same as
		     Same as
		     Use a	    inline editor for command entry.
		     Process each character as it is typed in
				    mode (always on).
		     Same as

	      Disable processing of the
		     file and uses the file instead of the file.  This mode is
		     on whenever the effective user ID (group ID) is not equal
		     to the real user ID (group ID).  Turning this off	causes
		     the  effective user ID and group ID to be set to the real
		     user ID and group ID.

	      Sort the positional parameters.

	      Exit after reading and executing one command.

	      Treat unset parameters as an error when substituting.

	      Print shell input lines as they are read.

	      Print commands and their arguments as they are executed.

	      Turn off
		     and options and stop examining arguments for options.

	      Do not change any of the options; useful in setting parameter
		     to a value beginning with If  no  arguments  follow  this
		     option, the positional parameters are unset.

       %
	      Rename  the positional parameters from to The default value of n
	      is n can be any arithmetic expression that evaluates to  a  non‐
	      negative number less than or equal to

	      Evaluate conditional expression expr.  See test(1) for usage and
	      description.  See also the subsection.

	      The arithmetic comparison operators are not restricted to	 inte‐
	      gers.   They  allow  any	arithmetic  expression.	 The following
	      additional primitive expressions are allowed:

		 True if	     file is a symbolic link.
		 True if	     file exists.
		 True if	     file1 is newer than file2.
		 True if	     file1 is older than file2.
		 True if	     file1 has the same device and i-node num‐
				     ber as file2.

       %
	      Print  the  accumulated  user and system times for the shell and
	      for processes run from the shell.

       %
	      Set arg as a command that is read and executed  when  the	 shell
	      receives	a sig signal.  (Note that arg is scanned once when the
	      trap is set and once when the trap is taken.)  Each sig  can  be
	      given  as	 the  number  or  name	of  a  signal.	Letter case is
	      ignored.	For example, and all specify the same signal.  Use  to
	      get a list of signals.

	      Trap  commands are executed in signal number order.  Any attempt
	      to set a trap on a signal that was  ignored  upon	 entering  the
	      current  shell  is  ineffective.	 Traps	remain in effect for a
	      given shell until explicitly changed with another command;  that
	      is,  a  trap  set	 within	 a function will remain in effect even
	      after the function returns.

	      If arg is (or if arg is omitted and the first sig	 is  numeric),
	      reset all traps for each sig to their original values.

	      If arg is the null string or ), each sig is ignored by the shell
	      and by the commands it invokes.

	      If sig is then arg is executed after each command.   If  sig  is
	      arg  is executed whenever a command has a nonzero exit code.  If
	      sig is or the command arg is executed on exit from the shell.

	      With no arguments, print a list of commands associated with each
	      signal name.

       &
	      Assign  types  and a value to a local named parameter name.  See
	      also the	special	 command.   Parameter  assignments  remain  in
	      effect after the command completes.  When invoked inside a func‐
	      tion, create a new instance of the parameter name.  The  parame‐
	      ter value and type are restored when the function completes.
	      The  following list of attributes can be specified.  Use instead
	      of to turn the options off.

	      Left justify and remove leading blanks from
		     value.  If n is nonzero, it  defines  the	width  of  the
		     field;  otherwise,	 it  is determined by the width of the
		     value of first assignment.	 When name  is	assigned,  the
		     value is filled on the right with blanks or truncated, if
		     necessary, to fit into  the  field.   Leading  zeros  are
		     removed  if the option is also set.  The option is turned
		     off.  Flagged as

	      Right justify and fill with leading blanks.
		     If n is nonzero, it defines the width of the field;  oth‐
		     erwise,  it  is  determined  by the width of the value of
		     first assignment.	The field is left-filled  with	blanks
		     or truncated from the end if the parameter is reassigned.
		     The option is turned off.	Flagged as

	      Right justify and fill with leading zeros
		     if the first nonblank character is a digit and the option
		     has  not  been set.  If n is nonzero it defines the width
		     of the field; otherwise, it is determined by the width of
		     the  value of first assignment.  Flagged as plus the flag
		     for or

	      Cause  name to refer to function	names  rather  than  parameter
		     names.   No  assignments can be made to the name declared
		     with the statement.  The only  other  valid  options  are
		     (which  turns on execution tracing for this function) and
		     (which allows the function to  remain  in	effect	across
		     shell  procedures	executed  in the same process environ‐
		     ment).  Flagged as

	      Parameter is an integer.
		     This makes arithmetic faster.  If n is nonzero it defines
		     the  output arithmetic base; otherwise, the first assign‐
		     ment determines the output base.  Flagged as

	      Convert all uppercase characters to lowercase.
		     The uppercase option is turned off.  Flagged as

	      Mark any given
		     name as "read only".  The name cannot be changed by  sub‐
		     sequent assignment.  Flagged as

	      Tag the named parameters.
		     Tags  are	user-definable	and have no special meaning to
		     the shell.	 Flagged as

	      Convert all lowercase characters to uppercase characters.
		     The lowercase option is turned off.  Flagged as

	      Mark any given
		     name for automatic export to the  environment  of	subse‐
		     quently executed commands.	 Flagged as

	      alone  displays a list of parameter names, prefixed by any flags
	      specified above.

	      displays the parameter names followed by their values.   Specify
	      one  or  more  of the option letters to restrict the list.  Some
	      options are incompatible with others.

	      displays the parameter names alone.  Specify one or more of  the
	      option letters to restrict the list.  Some options are incompat‐
	      ible with others.

	      Set or display a resource limit.	 The  limit  for  a  specified
	      resource is set when limit is specified.	The value of limit can
	      be a number in the unit specified with  each  resource,  or  the
	      keyword

	      The  and	flags specify whether the hard limit or the soft limit
	      is set for the given resource.  A hard limit cannot be increased
	      once  it	is  set.  A soft limit can be increased up to the hard
	      limit.  If neither nor is specified, the limit applies to	 both.
	      The current resource limit is printed when limit is omitted.  In
	      this case, the soft limit is printed unless is specified.	  When
	      more than one resource is specified, the limit name and unit are
	      printed before the value.

	      If no option is given, is assumed.

	      List all of the current resource limits.
	      The number of 512-byte blocks in the size of core dumps.
	      The number of kilobytes in the size of the data area.
	      The number of 512-byte blocks in files  written  by  child  pro‐
	      cesses
		     (files of any size can be read).
	      The number of file descriptors.
	      The number of kilobytes in the size of the stack area.
	      The number of seconds to be used by each process.

	      Set  the	user  file-creation  mask mask.	 mask can be either an
	      octal number or a symbolic value as described  in	 umask(1).   A
	      symbolic	value  shows  permissions that are unmasked.  An octal
	      value shows permissions that are masked off.

	      Without mask, print the current value of the mask.   With	 print
	      the  value  in  symbolic	format.	 Without print the value as an
	      octal number.  The output from either form can be	 used  as  the
	      mask of a subsequent invocation of

	      Remove  each  name from the alias list.  With remove all defini‐
	      tions from the current shell execution  environment.   See  also
	      the special command.

       %
	      Remove  the  named  shell	 parameters  from  the parameter list.
	      Their values and attributes  are	erased.	  Read-only  variables
	      cannot  be  unset.   With	 names	refer to function names.  With
	      names refer to variable names.  Unsetting and removes their spe‐
	      cial meaning, even if they are subsequently assigned to.

	      Wait  for the specified job to terminate or stop, and report its
	      status.  This status becomes the return code  for	 the  command.
	      Without  job,  wait  for all currently active child processes to
	      terminate and returns with a zero exit status.  See the  subsec‐
	      tion for a description of the format of job.

	      For each name, indicate how it would be interpreted if used as a
	      command name.  With produce a more verbose report.   With	 do  a
	      path  search for name, disregarding any use as an alias, a func‐
	      tion, or a reserved word.

   Comments
       A beginning with causes that word and all the following	characters  up
       to a newline to be ignored.

   Aliasing
       The  first word of each command is replaced by the text of an if an for
       this word has been defined.  An name consists of any number of  charac‐
       ters excluding metacharacters, quoting characters, file expansion char‐
       acters, parameter and command  substitution  characters,	 and  =.   The
       replacement  string  can	 contain any valid shell script, including the
       metacharacters listed above.  The first word of	each  command  in  the
       replaced	 text,	other  than  any  that	are  in	 the  process of being
       replaced, will be tested for additional aliases.	 If the last character
       of  the	alias  value is a the word following the alias is also checked
       for alias substitution.	Aliases can be used to redefine	 special  com‐
       mands,  but  cannot be used to redefine the keywords listed in the sub‐
       section.	 Aliases can be created, listed, and exported with the command
       and can be removed with the command.  Exported aliases remain in effect
       for subshells but must be reinitialized for separate invocations of the
       shell (see the subsection).

       Aliasing	 is  performed	when scripts are read, not while they are exe‐
       cuted.  Therefore, for it to take effect, an must  be  executed	before
       the command referring to the alias is read.

       Aliases	are  frequently	 used  as a shorthand for full path names.  An
       option to the aliasing facility allows the value of  the	 alias	to  be
       automatically  set  to the full path name of the corresponding command.
       These aliases are called aliases.  The value  of	 a  tracked  alias  is
       defined	the  first  time  the identifier is read and becomes undefined
       each time the variable is reset.	 These aliases remain tracked so  that
       the  next  reference  will redefine the value.  Several tracked aliases
       are compiled into the shell.  The option of the command	converts  each
       command name that is an into a tracked alias.

       The  following  are  compiled  into the shell but can be unset or rede‐
       fined:

   Tilde Substitution
       After alias substitution is performed, each word is checked to  see  if
       it  begins  with	 an  unquoted  tilde  If  it does, the word up to a is
       checked to see if it matches a user name in the file.  If  a  match  is
       found,  the and the matched login name are replaced by the login direc‐
       tory of the matched user.  If no match is found, the original  text  is
       left  unchanged.	  A  alone or before a is replaced by the value of the
       parameter.  A followed by a or is replaced by the value of the  parame‐
       ter  and	 respectively.	 In  addition, tilde substitution is attempted
       when the value of a parameter assignment begins with a

   Command Substitution
       The standard output from a command enclosed in parenthesis preceded  by
       a  dollar sign or a pair of grave accents can be used as part or all of
       a word; trailing newlines are removed.  In the second  (archaic)	 form,
       the string between the accents is processed for special quoting charac‐
       ters before the command is executed.  See the subsection.  The  command
       substitution  can be replaced by the equivalent but faster Command sub‐
       stitution of most special commands that do not perform input/output re‐
       direction are carried out without creating a separate process.

       An  arithmetic  expression enclosed in double parenthesis preceded by a
       dollar sign is replaced by  the	value  of  the	arithmetic  expression
       within the double parenthesis.  See the subsection for a description of
       arithmetic expressions.

   Parameter Substitution
       A is an identifier, one or more decimal digits, or one of  the  charac‐
       ters  and A (a parameter denoted by an identifier) has a value and zero
       or more attributes.   Named  parameters	can  be	 assigned  values  and
       attributes  with	 the special command.  Exported parameters pass values
       and attributes to the environment.

       The shell supports a limited one-dimensional array facility.   An  ele‐
       ment  of	 an array parameter is referenced by a subscript.  A subscript
       is denoted by a followed by an arithmetic expression, followed by a See
       the  subsection.	  To  assign  values to an array, use The value of all
       subscripts must be in the range of through Arrays need not be declared.
       Any  reference to a named parameter with a valid subscript is legal and
       an array is created if necessary.  Referencing an array parameter with‐
       out a subscript is equivalent to referencing the first element.

       If  the	integer	 attribute  is	set  for name, the value is subject to
       arithmetic evaluation.

       Positional parameters, parameters denoted by a number, can be  assigned
       values  with  the special command.  Parameter is set from argument zero
       when the shell is invoked.

       Use the prefix character to specify the value of a parameter  for  sub‐
       stitution.

       Substitute the value of the parameter, if any.
		      Braces are required when parameter is fol‐
		      lowed by a letter,  digit,  or  underscore
		      that  should not be interpreted as part of
		      its name or when a named parameter is sub‐
		      scripted.	  If  parameter	 is  one or more
		      digits, it is a positional  parameter.   A
		      positional  parameter  of	 more  than  one
		      digit must be  enclosed  in  braces.   The
		      shell reads all the characters from to the
		      matching as part of the same word, even if
		      it contains braces or metacharacters.

		      If  parameter  is	 or  all  the positional
		      parameters, starting with are  substituted
		      (separated  by  a	 field separator charac‐
		      ter).  See the subsection.

		      If an array parameter with subscript or is
		      used,  the  value for each element is sub‐
		      stituted (separated by a	field  separator
		      character).

       If	      parameter	 is  or the number of positional
		      parameters is substituted.  Otherwise, the
		      length  of  the  value of the parameter is
		      substituted.

       Substitute the number of elements in the array.

       If	      parameter is set and is  nonnull,	 substi‐
		      tute   its  value;  otherwise,  substitute
		      word.

       If	      parameter is not set or is null, set it to
		      word;  then  substitute  the  value of the
		      parameter.  Positional parameters may  not
		      be assigned in this way.

       If	      parameter	 is  set and is nonnull, substi‐
		      tute its value; otherwise, print word  and
		      exit  from the shell.  If word is omitted,
		      a standard message is printed.

       If	      parameter is set and is  nonnull,	 substi‐
		      tute word; otherwise, substitute nothing.

       If the shell   pattern  matches	the  beginning of
		      the value of parameter,  the  value
		      of  this	substitution is the value
		      of the parameter with  the  matched
		      portion	deleted;  otherwise,  the
		      value of this parameter is  substi‐
		      tuted.   In  the	former	case, the
		      smallest	 matching   pattern    is
		      deleted;	in  the	 latter case, the
		      largest	matching    pattern    is
		      deleted.	  These	  characters,  or
		      should be escaped	 by  a	backslash
		      (\) or quotes ('').

       If	      the  shell  pattern  matches
		      the  end	of  the	 value	of
		      parameter,   the	 value	of
		      parameter with  the  matched
		      part  is deleted; otherwise,
		      substitute  the	value	of
		      parameter.   In  the former,
		      the smallest  matching  pat‐
		      tern is deleted; in the lat‐
		      ter,  the	 largest  matching
		      pattern  is  deleted.  These
		      characters,  or  should	be
		      escaped  by  a backslash (\)
		      or quotes ('').

       In the above, word is not evaluated  unless
       it  is  used  as	 the  substituted  string.
       Thus, in the following example, is executed
       only if is not set or is null:

       If  the	colon  is  omitted  from the above
       expressions,  the  shell	 only  checks	to
       determine whether or not parameter is set.

       · The following parameters are set automat‐
       ically by the shell:

       The string used	to  call  the  command	or
       script,
		      set from invocation argument
		      zero.

       The positional parameters.

       All the set  positional	parameters,  sepa‐
       rated by a field separator character.
		      See the subsection.

       The  number of set positional parameters in
       decimal.

       Flags supplied to the shell  on	invocation
       or by the
		      command.

       The  decimal  exit  status  returned by the
       last executed command.

       The process number of this shell.

       Initially,     the absolute  path  name	of
		      the  shell  or  script being
		      executed, as passed  in  the
		      environment.   Subsequently,
		      it  is  assigned	the   last
		      argument	 of  the  previous
		      command.	This parameter	is
		      not  set	for commands which
		      are   asynchronous.     This
		      parameter	 is  also  used to
		      hold the name of the  match‐
		      ing  file	 when checking for
		      mail.

       The process number of the  last	background
       command invoked.

       The value of   as  set by the most recently
		      failed  system  call.   This
		      value   is  system-dependent
		      and is intended  for  debug‐
		      ging purposes.

       The  line number of the current line within
       the script or
		      function being executed.

       The previous working directory set by the
		      command.

       The value of the last option argument  pro‐
       cessed by the
		      special command.

       If set to 0,   will suppress error messages
		      from  the	 special  command.
		      is initially set to 1.

       The  index of the last option argument pro‐
       cessed by the
		      special command.

       The process number of  the  parent  of  the
       shell.

       The present working directory set by the
		      command.

       Each  time  this	 parameter is evaluated, a
       random integer,
		      uniformly	       distributed
		      between 0 and 32767, is gen‐
		      erated.	The  sequence	of
		      random  numbers  can be ini‐
		      tialized	by   assigning	 a
		      numeric value to

       Set by the     compound command, and by the
		      special command when no name
		      is supplied.

       Each time this parameter is referenced,
		      the  number of seconds since
		      shell	invocation	is
		      returned.	 If this parameter
		      is  assigned  a  value,  the
		      value  returned  upon refer‐
		      ence is the value	 that  was
		      assigned	plus the number of
		      seconds  since  the  assign‐
		      ment.

       ·  The following parameters are used by the
       shell:

       The search path for the
		      command, a list of  directo‐
		      ries separated by colons.

       If this variable is set,
		      its  value is used to define
		      the width of the edit window
		      for the shell edit modes and
		      for printing lists.

       If the value of this variable ends in
		      or and the variable  is  not
		      set,    the    corresponding
		      option is turned on (see the
		      special command.

       If this parameter is set,
		      parameter	  substitution	is
		      performed on  the	 value	to
		      generate	the  path  name of
		      the script  to  be  executed
		      when  the	 shell	is invoked
		      (see the subsection).   This
		      file  is	typically used for
		      and definitions.

		      By default, script  is  exe‐
		      cuted for interactive shells
		      only.  Under the environment
		      (see   standards(5)),   this
		      file is  executed	 for  both
		      interactive and non-interac‐
		      tive shells.

       The default editor name for the
		      command.

       The search path for function definitions,
		      a list of directories  sepa‐
		      rated  by colons.	 This path
		      is searched when a  function
		      with the attribute is refer‐
		      enced and when a command	is
		      not found.  If an executable
		      file is found,  then  it	is
		      read  and	 executed  in  the
		      current environment.

       If this parameter is set when the shell	is
       invoked,
		      its  value  is the path name
		      of the file that is used	to
		      store  the  command history.
		      The default value is If  the
		      user  is	a superuser and no
		      is given,	 then  no  history
		      file  is used.  See the sub‐
		      section and the section.

       If this parameter is set when the shell	is
       invoked,
		      the   number  of	previously
		      entered commands	accessible
		      to   this	  shell	  will	be
		      greater  than  or	 equal	to
		      this number.  The default is
		      128.

       The default argument (home  directory)  for
       the
		      command.

       Internal field separators,
		      normally	 space,	 tab,  and
		      newline, that  are  used	to
		      separate	  command    words
		      resulting	 from  command	or
		      parameter	 substitution  and
		      for  separating  words  with
		      the   special   command  The
		      first   character	  of   the
		      parameter	 is  used to sepa‐
		      rate arguments for the  sub‐
		      stitution	 (see  the subsec‐
		      tion).  If the value  of	is
		      space,  tab, and newline, or
		      if is unset and it is  being
		      used to separate the results
		      of command or parameter sub‐
		      stitution,  any  sequence of
		      characters serves to delimit
		      words;	otherwise,    each
		      occurrence of a character in
		      serves  to  delimit  a word.
		      If the value of is null,	no
		      word splitting is done.

       The locale of your system, which is made up
       of three parts:
		      language,	  territory,   and
		      code  set.   The	default is
		      the locale.  See environ(5).

       The overriding value for
		      and the variables.  See env‐
		      iron(5).

       The  collating sequence to use when sorting
       names and
		      when character ranges  occur
		      in   patterns.	See  envi‐
		      ron(5).

       The character classification information to
       use.
		      Changing	the value of after
		      the shell has  started  does
		      not  affect the lexical pro‐
		      cessing of shell commands in
		      the  current shell execution
		      environment  or	its   sub‐
		      shells.  See environ(5).

		      The  shell  uses	to  detect
		      nonprintable  characters	in
		      the  input and tries to han‐
		      dle them when the or editing
		      mode   is	  selected.    Not
		      starting a new shell session
		      after setting may affect the
		      display	of    nonprintable
		      input  characters	 in the or
		      editing mode.

       The  language  in  which	 system	  messages
       appear,
		      and  the	language  that the
		      system  expects	for   user
		      input  of	 and strings.  See
		      environ(5).

       The currency symbol and monetary value for‐
       mat.
		      See environ(5).

       The numeric format.
		      See environ(5).

       The date and time format.
		      See environ(5).

       If this variable is set,
		      the  value is used to deter‐
		      mine the column  length  for
		      printing lists.  lists print
		      vertically until about  two-
		      thirds of lines are filled.

       If  this	 parameter is set to the name of a
       mail file
		      and  the	parameter  is  not
		      set,  the	 shell informs the
		      user of arrival of  mail	in
		      the specified file.

       How often (in seconds)
		      the shell checks for changes
		      in the modification time	of
		      any  of  the files specified
		      by the or	 parameters.   The
		      default  value  is  600 sec‐
		      onds.   When  the	 time  has
		      elapsed,	the  shell  checks
		      before  issuing	the   next
		      prompt.

       A list of file names separated by colons.
		      If  this	parameter  is set,
		      the shell informs	 the  user
		      of  any modifications to the
		      specified	 files	that  have
		      occurred	 within	 the  last
		      seconds.	Each file name can
		      be  followed by a and a mes‐
		      sage to be printed, in which
		      case    the   message   will
		      undergo parameter	 and  com‐
		      mand  substitution  with the
		      parameter	 defined  as   the
		      name  of	the  changed file.
		      The default message is

       The search path for message catalogs,
		      a list of directories  sepa‐
		      rated by colons.

       The  search  path  for  commands, a list of
       directories separated by colons.
		      See the subsection.

       The value of this parameter is expanded for
       parameter
		      substitution,  to define the
		      primary prompt string.   The
		      default  value  is  "".  The
		      character	 in  the   primary
		      prompt string is replaced by
		      the command number.  See the
		      subsection.

       Secondary prompt string for command comple‐
       tion.
		      The default value is "".

       Selection prompt string used within a
		      loop.  If unset, it defaults
		      to "".

       Execution  trace	 string that precedes each
       line of an execution trace.
		      See the special command.	If
		      unset, it defaults to "".

       The  path  name of the shell is kept in the
       environment.
		      When invoked, the	 shell	is
		      restricted  if  the value of
		      this variable contains an in
		      the base name.

       If set to a value greater than zero,
		      the  shell will terminate if
		      a	 command  is  not  entered
		      within the prescribed number
		      of seconds after issuing the
		      prompt.	 (Note	 that  the
		      shell can be compiled with a
		      maximum bound for this value
		      which cannot be exceeded.)

       Invokes the corresponding option	 when  the
       value of this variable ends in
		      or See the special command.

       The  shell  gives  default values to and On
       the other hand, and are never set automati‐
       cally by the shell (although and are set by
       see login(1)).

   Blank Interpretation
       After parameter and  command  substitution,
       the results of substitution are scanned for
       field separator characters (defined in  and
       split  into  distinct  arguments	 when such
       characters  are	found.	 retains  explicit
       null  arguments	(or  but  removes implicit
       null arguments (those resulting from param‐
       eters that have null values).

   File Name Generation
       Following  substitution,	 each command word
       is processed as a  pattern  for	file  name
       expansion  unless  expansion  has been dis‐
       abled with the special command.	 The  form
       of  the	patterns  is  the  defined in reg‐
       exp(5).	The word is replaced  with  sorted
       file  names  matching  the  pattern.  If no
       file name is found that	matches	 the  pat‐
       tern, the word is left unchanged.

       In  addition  to	 the notation described in
       regexp(5),  recognizes  composite  patterns
       made  up	 of one or more patterns separated
       from each other with a  Composite  patterns
       can  be formed with one or more of the fol‐
       lowing:

	      Matches any one of  the  given  pat‐
	      terns.
	      Matches  zero or more occurrences of
	      the given patterns.
	      Matches one or more  occurrences	of
	      the given patterns.
	      Matches  exactly	one  of	 the given
	      patterns.
	      Matches anything, except one of  the
	      given patterns.

   Quoting
       Each of the metacharacters (see the subsec‐
       tion) has a special meaning  to	the  shell
       and  terminates	a  word	 unless quoted.	 A
       character may be (that is,  made	 to  stand
       for  itself)  by	 preceding it with a back‐
       slash The pair is ignored; the current  and
       following lines are concatenated.

       All  characters	enclosed between a pair of
       apostrophes are quoted.	An apostrophe can‐
       not appear within apostrophes.

       Parameter  and  command substitution occurs
       inside quotation marks (...).   quotes  the
       characters , and

       Inside  grave accent marks quotes the char‐
       acters  and  If	the  grave  accents  occur
       within  quotation  marks,  also	quotes the
       character .

       The meanings of and are identical when  not
       quoted  or when used as a parameter assign‐
       ment value or as	 a  file  name.	  However,
       when used as a command argument, is equiva‐
       lent to , whereas is  equivalent	 to  dd...
       (where d is the first character of

       The  special meaning of keywords or aliases
       can be removed by quoting any character	of
       the  name.   The	 recognition  of  function
       names or special command	 names	cannot	be
       altered by quoting them.

   Arithmetic Evaluation
       Integer	arithmetic  is	provided  with the
       special command Evaluations  are	 performed
       using  long  integer arithmetic.	 Constants
       take the form or n, where base is a decimal
       number  between	two  and thirty-six repre‐
       senting the arithmetic base and n is a num‐
       ber  in	that base.  If is omitted, base 10
       is used.

       An arithmetic expression uses the same syn‐
       tax,   precedence,   and	 associativity	of
       expression as  the  C  language.	  All  the
       integral operators, other than and are sup‐
       ported.	Variables  can	be  referenced	by
       name  within an arithmetic expression with‐
       out using the parameter	substitution  syn‐
       tax.   When  a  variable is referenced, its
       value is evaluated as an arithmetic expres‐
       sion.

       A  variable can be typed as an integer with
       the option of the special  command,  as	in
       Arithmetic  evaluation  is performed on the
       value of each assignment to a variable with
       the  attribute.	 If  you do not specify an
       arithmetic base, the  first  assignment	to
       the   variable  determines  the	arithmetic
       base.  This base	 is  used  when	 parameter
       substitution occurs.

       Since  many  of	the  arithmetic	 operators
       require quoting, an alternative form of the
       command	 is  provided.	 For  any  command
       beginning with  all  characters	until  the
       matching	 are  treated  as a quoted expres‐
       sion.  More  precisely,	is  equivalent	to
       ....

       Arithmetic  expressions given with command,
       and will be  processed  according  to  ISOC
       standard	 with  the exception of and opera‐
       tors.

   Prompting
       When used interactively, the shell  prompts
       with the value of before reading a command.
       Whenever a newline is received and  further
       input  is needed to complete a command, the
       secondary prompt (the value of is issued.

   Conditional Expressions
       A is used with the compound command to test
       attributes of files and to compare strings.
       Word splitting and file name generation are
       not performed on the words between and (See
       also the special command.)  Each expression
       can  be constructed from one or more of the
       following unary or binary expressions:

	      True, if		  file exists.
	      True, if		  file exists  and
				  is  a block spe‐
				  cial file.
	      True, if		  file exists  and
				  is  a	 character
				  special file.
	      True, if		  file exists  and
				  is a directory.
	      True, if		  file exists.
	      True, if		  file	exists and
				  is  an  ordinary
				  file.
	      True, if		  file	exists and
				  has  its  setgid
				  bit set.
	      True, if		  file	exists and
				  is  a	  symbolic
				  link.
	      True, if		  file	exists and
				  has  its  sticky
				  bit set.
	      True, if length of  string	is
				  nonzero.
	      True, if the set option named
				  option is on.
	      True, if		  file exists  and
				  is  a	 fifo spe‐
				  cial file  or	 a
				  pipe.
	      True, if		  file	exists and
				  is  readable	by
				  current process.
	      True, if		  file	exists and
				  has	 a    size
				  greater     than
				  zero.
	      True, if file descriptor number
				  fildes  is  open
				  and  is  associ‐
				  ated with a ter‐
				  minal device.
	      True, if		  file	exists and
				  has  its  setuid
				  bit set.
	      True, if		  file	exists and
				  is  writable	by
				  the	   current
				  process.
	      True, if		  file exists  and
				  is executable by
				  the	   current
				  process.	If
				  file exists  and
				  is  a directory,
				  then the current
				  process has per‐
				  mission	to
				  search   in  the
				  directory.
	      True, if length of  string is zero.
	      True, if		  file exists  and
				  is   a  symbolic
				  link.
	      True, if		  file exists  and
				  is  owned by the
				  effective   user
				  ID	of    this
				  process.
	      True, if		  file exists  and
				  its	     group
				  matches      the
				  effective  group
				  ID	of    this
				  process.
	      True, if		  file	exists and
				  is a socket.
	      True, if		  file1 exists and
				  is   newer  than
				  file2.
	      True, if		  file1 exists and
				  is   older  than
				  file2.
	      True, if		  file1 and  file2
				  exist	 and refer
				  to   the    same
				  file.
	      True, if		  string   matches
				  pattern.
	      True, if		  string does  not
				  match pattern.
	      True, if		  string1    comes
				  before   string2
				  based	  on   the
				  ASCII	 value	of
				  their	   charac‐
				  ters.
	      True, if		  string1    comes
				  after	   string2
				  based	  on   the
				  ASCII	 value	of
				  their	   charac‐
				  ters.
	      True, if		  exp1 is equal to
				  exp2.
	      True, if		  exp1	 is    not
				  equal to exp2.
	      True, if		  exp1	 is   less
				  than exp2.
	      True, if		  exp1 is  greater
				  than exp2.
	      True, if		  exp1	 is   less
				  than or equal to
				  exp2.
	      True, if		  exp1	is greater
				  than or equal to
				  exp2.

       A  compound  expression	can be constructed
       from these primitives by using any  of  the
       following,  listed  in  decreasing order of
       precedence.

	      True, if		  exp	is   true.
				  Used	 to  group
				  expressions.
	      True, if		  exp is false.
	      True, if		  exp1	and   exp2
				  are both true.
	      True, if either	  exp1	or exp2 is
				  true.

   Input/Output
       Before a command is executed, its input and
       output  can  be	redirected using a special
       notation interpreted  by	 the  shell.   The
       following  can appear anywhere in a simple-
       command or may precede or follow a  command
       and  are	 not passed on to the invoked com‐
       mand.  Command and  parameter  substitution
       occurs before word or digit is used, except
       as  noted  below.   File	 name	generation
       occurs only if the pattern matches a single
       file and blank interpretation is	 not  per‐
       formed.

	      Use file	     word    as	  standard
			     input (file  descrip‐
			     tor

	      Use file	     word as standard out‐
			     put (file	descriptor
			     If	 the file does not
			     exist, it is created.
			     If	 the  file exists,
			     and the option is on,
			     an error occurs; oth‐
			     erwise, the  file	is
			     truncated	 to   zero
			     length.   Note   that
			     the   test	  is  only
			     applied  to   regular
			     files,  not  to named
			     pipes or  other  file
			     types.

	      Same as	     except  that it over‐
			     rides the option.

	      Use file	     word as standard out‐
			     put.    If	 the  file
			     exists,   output	is
			     appended  to  it  (by
			     first  searching  for
			     the     end-of-file);
			     otherwise,	 the  file
			     is created.

	      Open file	     word  for reading and
			     writing  as  standard
			     input.

	      The shell input is read up to a line
	      that matches
			     word, or to  an  end-
			     of-file.	No parame‐
			     ter     substitution,
			     command  substitution
			     or file name  genera‐
			     tion  is performed on
			     word.  The	 resulting
			     document,	 called	 a
			     becomes the  standard
			     input.   See also the
			     section.

			     If any  character	of
			     word  is  quoted,	no
			     interpretation	is
			     placed upon the char‐
			     acters of	the  docu‐
			     ment.	Otherwise,
			     parameter and command
			     substitution  occurs,
			     is ignored, and  must
			     be	 used to quote the
			     characters	 and   the
			     first   character	of
			     word.

			     If is appended to all
			     leading	tabs   are
			     stripped  from   word
			     and  from	the  docu‐
			     ment.

	      The  standard  input  is	duplicated
	      from file descriptor
			     digit (see dup(2)).

	      The standard output is duplicated to
	      file descriptor
			     digit (see dup(2)).

	      The standard input is closed.

	      The standard output is closed.

	      The  input  from	the  coprocess	is
	      moved to standard input.

	      The output to the coprocess is moved
	      to standard output.

       If any of the above  redirections  is  pre‐
       ceded  by  a  digit  to the file descriptor
       used is the one	specified  by  the  digit,
       instead	of the default (standard input) or
       (standard output).  For example:

       means open file descriptor 2 for writing as
       a  duplicate  of file descriptor 1.  Output
       directed to file descriptor 2 is written in
       the   same   location  as  output  to  file
       descriptor 1.

       Order is significant in	redirection.   The
       shell  evaluates	 each redirection in terms
       of the (file descriptor,	 file)	assignment
       at the time of evaluation.  For example:

       first  assigns  file  descriptor	 1 to file
       fname.  It then assigns file  descriptor	 2
       to  the	file assigned to file descriptor 1
       (that is, fname).

       If the order of redirection is reversed, as
       in

       file  descriptor	 2 is assigned to the file
       assigned to file descriptor 1 (probably the
       terminal)  and  then  file  descriptor 1 is
       assigned to file fname.

       By using the redirection	 operators  above,
       the  input and output of a coprocess may be
       moved to a numbered file descriptor, allow‐
       ing  other  commands  to	 write to them and
       read from them.	If the input of	 the  cur‐
       rent  coprocess is moved to a numbered file
       descriptor,  another   coprocess	  may	be
       started.

       If a command is followed by and job control
       is inactive, the default standard input for
       the  command  is	 the empty file Otherwise,
       the environment for the execution of a com‐
       mand  contains  the file descriptors of the
       invoking shell as modified by  input/output
       specifications.

   Environment
       The  (see  environ(5))  is  a list of name-
       value pairs passed to an	 executed  program
       much  like  a  normal  argument	list.  The
       names must be identifiers  and  the  values
       are character strings.  The shell interacts
       with the environment in several ways.  When
       invoked,	 the  shell  scans the environment
       and  creates  a	parameter  for	each  name
       found, gives it the corresponding value and
       marks  it  Executed  commands  inherit  the
       environment.  If the user modifies the val‐
       ues of these parameters or creates new ones
       by  using the or special commands, the val‐
       ues become part of  the	environment.   The
       environment seen by any executed command is
       thus composed of any name-value pairs orig‐
       inally inherited by the shell, whose values
       may be modified by the current shell,  plus
       any  additions  which  must  be noted in or
       commands.

       The environment for any simple  command	or
       function	 can  be augmented by prefixing it
       with one or more parameter assignments.	 A
       parameter  assignment  argument	takes  the
       form For example, both the following

       are equivalent (as far as the execution	of
       cmd  is	concerned,  except for the special
       commands that are  preceded  by	a  percent
       sign (%).

       If the option is set, all parameter assign‐
       ment arguments are placed in  the  environ‐
       ment,  even if they occur after the command
       name.  The following echo statement  prints
       After  the  option  is set, the second echo
       statement prints only

       This  feature  is  intended  for	 use  with
       scripts	written	 for early versions of the
       shell  and  its	use  in	 new  scripts	is
       strongly discouraged.  It is likely to dis‐
       appear someday.

   Functions
       The command (described in  the  subsection)
       defines	shell  functions.  Shell functions
       are  read  and  stored  internally.   Alias
       names  are  resolved  when  the function is
       read.  Functions	 are  executed	like  com‐
       mands,  with  the arguments passed as posi‐
       tional parameters.  (See the subsection.)

       Functions execute in the	 same  process	as
       the  caller and share all files and current
       working directory with the  caller.   Traps
       defined	by  the	 caller	 remain	 in effect
       within the function until  another  command
       is  executed.   Traps set within a function
       remain  in  effect   after   the	  function
       returns.	  Ordinarily, variables are shared
       between the calling program and	the  func‐
       tion.   However, the special command can be
       used within  a  function	 to  define  local
       variables  whose scope includes the current
       function and all functions it calls.

       The special command is used to return  from
       function	 calls.	  Errors  within functions
       return control to the caller.

       Function identifiers can be listed with the
       option  of  the	special command.  Function
       identifiers and the associated text of  the
       functions  can  be  listed with the option.
       Functions can be undefined with the  option
       of the special command.

       Ordinarily,  functions  are  unset when the
       shell executes a shell script.  The  option
       of  the	command	 allows	 a  function to be
       exported to scripts that are executed with‐
       out  reinvoking	the shell.  Functions that
       must be defined across separate invocations
       of the shell should be placed in the file.

   Jobs
       If  the option of the command is turned on,
       an interactive shell associates a job  with
       each pipeline.  It keeps a table of current
       jobs, printed by the command,  and  assigns
       them  small integer numbers.  When a job is
       started	asynchronously	with   the   shell
       prints a line that looks like:

       indicating  that	 job  number 1 was started
       asynchronously  and  had	 one   (top-level)
       process whose process ID was 1234.

       If  you	are  running  a job and wish to do
       something else, you can	type  the  suspend
       character  (the	character defined with see
       stty(1)) to send a signal  to  the  current
       job.  The shell then indicates that the job
       has been and prints another  prompt.   Then
       you can manipulate the state of this job by
       putting it in the background with the  com‐
       mand,  running  other commands, and eventu‐
       ally returning the job  to  the	foreground
       with  the  command.  A suspend takes effect
       immediately  and	 resembles  an	interrupt,
       since  pending  output and unread input are
       discarded when the suspend is entered.

       A job running in the background stops if it
       tries  to  read	from  the terminal.  Back‐
       ground jobs normally are allowed to produce
       output,	but  can be disabled with the com‐
       mand.   If  the	user  sets  this  terminal
       option, background jobs stop when trying to
       produce output.

       There are several ways to refer to jobs	in
       the shell.  A job can be referred to by the
       process ID of any process in the job or	by
       one of the following:

	      The job with the given number.
	      Any  job	whose  command line begins
	      with
			   string.
	      Any job whose command line contains
			   string.
	      Current job.
	      Equivalent to
	      Previous job.

       The shell learns immediately when a process
       changes	state.	It informs the user when a
       job is blocked and prevented  from  further
       progress,  but only just before it prints a
       prompt.

       When the monitor mode  is  on,  each  back‐
       ground job that completes triggers any trap
       set for

       If you try to exit from	shell  while  jobs
       are  stopped,  you are warned with the mes‐
       sage You can use the  command  to  identify
       them.   If  you	immediately  try  to  exit
       again, the shell will not warn you a second
       time,  and  the stopped jobs will be termi‐
       nated.

       If you try to leave the	shell  while  jobs
       are running, you are not warned.	 The shell
       exits silently and sets the parent  of  the
       running jobs to the process (number 1).

   Signals
       The  and signals for an invoked command are
       ignored if the command is followed  by  and
       the option is off.  Otherwise, signals have
       the values inherited by the shell from  its
       parent,	with  the exception of signal (but
       see also the special command).

   Execution
       Substitutions are made each time a  command
       is  executed.   checks  the command name to
       determine whether it matches a special com‐
       mand.   If  it  does, it is executed within
       the current shell process.

       Next, checks the command name to	 determine
       whether	it matches one of the user-defined
       functions.  If it  does,	 saves	the  posi‐
       tional  parameters,  then  sets them to the
       arguments of the function call.	The  posi‐
       tional  parameter  is  unchanged.  When the
       function completes or issues a restores the
       positional  parameter list.  The value of a
       function is the value of the  last  command
       executed.   A  function	is executed in the
       current shell process.

       If a command name  is  not  a  user-defined
       function	 or  a	special command, creates a
       process and attempts to execute the command
       using an system call (see exec(2)).

       The shell parameter defines the search path
       for the directory containing  the  command.
       Alternative  directory  names are separated
       by a colon The default path is  (specifying
       and  the current directory, in that order).
       Note that the current directory	is  speci‐
       fied  by a null path name, which can appear
       immediately after the equal  sign,  between
       colon delimiters, or at the end of the path
       list.  The search path is not used  if  the
       command	name  contains	a  Otherwise, each
       directory in the path is	 searched  for	an
       executable  file.   If the file has execute
       permissions but is not a	 directory  or	an
       executable  object code file, it is assumed
       to be a script file, which  is  a  file	of
       data  for an interpreter.  If the first two
       characters of the script file  are  expects
       an  interpreter	path name to follow.  then
       attempts to execute  the	 specified  inter‐
       preter  as  a  separate process to read the
       entire script file.  If a call to fails, is
       spawned	to interpret the script file.  All
       nonexported aliases, functions,	and  named
       parameters  are	removed	 in this case.	If
       the shell command file does not	have  read
       permission,  or	if the and/or bits are set
       on the file, the shell executes an agent to
       set  up	the  permissions  and  execute the
       shell with the shell  command  file  passed
       down as an open file.  A parenthesized com‐
       mand is also executed in a subshell without
       removing nonexported quantities.

   Command Reentry
       The text of the last (default 128) commands
       entered from a terminal device is saved	in
       a  history  file.   The file is used if the
       variable is not set or writable.	  A  shell
       can  access the commands of all interactive
       shells that use the same named The  special
       command	is  used to list or edit a portion
       of this file.  The portion of the  file	to
       be edited or listed can be selected by num‐
       ber or by giving	 the  first  character	or
       characters  of  the command.  A single com‐
       mand or range of commands can be specified.
       If  you do not specify an editor program as
       an argument to the value of  the	 parameter
       is  used.  If is not defined, is used.  The
       edited command is  printed  and	reexecuted
       upon  leaving  the editor.  The editor name
       is used to skip the editing  phase  and	to
       reexecute  the  command.	  In  this case, a
       substitution parameter of the form  can	be
       used  to	 modify	 the command before execu‐
       tion.  For example, if is aliased to typing
       reexecutes  the	most  recent  command that
       starts with the	letter	and  replaces  the
       first  occurrence  of  the  string with the
       string

       The history file will be trimmed	 when  all
       of the following conditions occurs:

	      Its  size is greater than four kilo‐
	      bytes.

	      The number of commands in it is more
	      than

	      The  file	 has  not been modified in
	      the last ten minutes.

	      The user has  write  permission  for
	      the  directory  in which the history
	      file resides.

       If any one of the above conditions does not
       occur,	the   history  file  will  not	be
       trimmed.	 When the history file is trimmed,
       the  latest  commands  will be available in
       the history file.

   Command Line Editing
       Normally, each command line typed at a ter‐
       minal  device  is  followed by a newline or
       return.	If one of the or options  is  set,
       you  can edit the command line.	An editing
       option is automatically selected each  time
       the  or variable is assigned a value ending
       in one of these option names.

       The  editing  features  require	that   the
       user's  terminal accept return without line
       feed and that a space (" ") must	 overwrite
       the  current  character on the screen.  ADM
       terminal	   users    should     set     the
       "space − advance"    switch   to	  "space".
       Hewlett-Packard terminal users  should  set
       the straps to "bcGHxZ etX".

       The  editing  modes enable the user to look
       through a window at the current line.   The
       default	window	width  is  80,	unless the
       value of is defined.  If the line is longer
       than  the  window  width	 minus two, a mark
       displayed at the end of the window notifies
       the user.  The mark is one of:

	      The line extends to the right.
	      The line extends to the left.
	      The  line	 extends  to both sides of
	      the window.

       As the cursor moves and reaches the  window
       boundaries,  the	 window	 is centered about
       the cursor.

       The search commands in each edit mode  pro‐
       vide  access  to	 the  history  file.  Only
       strings are matched, not patterns, although
       a leading in the string restricts the match
       to begin at  the	 first	character  in  the
       line.

       Changing	  the	environment  variable  can
       affect the editors.  See the subsection.

   emacs/gmacs Editing Mode
       This mode  is  invoked  by  either  the	or
       option.	 The  sole  difference is how they
       handle Control-T.

       To edit, the user moves the cursor  to  the
       point  needing  correction  and	inserts or
       deletes characters or words.   All  editing
       commands	 are  control characters or escape
       sequences.  The notation for control  char‐
       acters  is  caret  followed by a character.
       For example, is the notation for Control-F.
       This  is	 entered  by holding down the Ctrl
       (control) key and pressing The shift key is
       pressed.	 The notation indicates the delete
       (DEL) key.

       The notation for escape sequences  is  fol‐
       lowed  by  a character.	For example, (pro‐
       nounced is entered by pressing  the  escape
       key  (followed  by pressing is the notation
       for escape followed by shift (capital)

       All edit commands operate from any place on
       the line (not only at the beginning).  Nei‐
       ther the return	nor  the  newline  key	is
       entered	after  edit  commands, except when
       noted.

	      Move  cursor  forward  (right)   one
	      character.

	      Move cursor forward one word.
			     (The editor's idea of
			     a word is a string of
			     characters consisting
			     of only letters, dig‐
			     its and underscores.)

	      Move   cursor  backward  (left)  one
	      character.

	      Move cursor backward one word.

	      Move cursor to start of line.

	      Move cursor to end of line.

	      Move cursor forward to character
			     char on current line.

	      Move cursor backward to character
			     char on current line.

	      Interchange the cursor and mark.

	      erase	     Delete previous char‐
			     acter.    The   erase
			     character	is   user-
			     definable	 with  the
			     command; it  is  usu‐
			     ally  set to The sys‐
			     tem default is

	      Delete current character.

	      eof	     Terminate	the  shell
			     if	 the  current line
			     is	 null.	 The   eof
			     character	 is  user-
			     definable	with   the
			     command;  it  is usu‐
			     ally set to The  sys‐
			     tem default is

	      Delete current word.

	      Delete	previous    word    (meta-
	      backspace).

	      Delete previous word.

	      Delete previous word (meta-delete).
			     If	  your	 interrupt
			     character	 is  (DEL,
			     the  default),   this
			     command	will   not
			     work.

	      In	     mode, transpose  cur‐
			     rent  character  with
			     next  character.	In
			     mode,  transpose  two
			     previous characters.

	      Capitalize current character.

	      Capitalize current word.

	      Change the current  word	to  lower‐
	      case.

	      Delete from the cursor to the end of
	      the line.
			     If	 preceded   by	 a
			     numerical	 parameter
			     whose value  is  less
			     that the current cur‐
			     sor  position,   then
			     delete from the given
			     position  up  to  the
			     cursor.   If preceded
			     by a numerical param‐
			     eter  whose  value is
			     greater than the cur‐
			     rent cursor position,
			     then delete from  the
			     cursor   up   to  the
			     given position.

	      Kill from the cursor to the mark.

	      Push the region from the	cursor	to
	      the mark on the stack.

	      kill	     Kill  the entire cur‐
			     rent  line.   If  two
			     kill  characters  are
			     entered  in   succes‐
			     sion,  all subsequent
			     consecutive      kill
			     characters	  cause	 a
			     line   feed   (useful
			     when using paper ter‐
			     minals).	The   kill
			     character	 is  user-
			     definable	with   the
			     command;  it  is usu‐
			     ally set  to  or  The
			     system default is

	      Restore last item removed from line
			     (yank  item  back	to
			     the line).

	      Line feed and print current line.

	      Set mark	     (null character).

	      Set mark	     (meta-space).

	      Execute the current line
			     (newline).

	      Execute the current line
			     (return).

	      Fetch previous command.
			     Each time is entered,
			     the  previous command
			     in the  history  list
			     is accessed.

	      Fetch next command.
			     Each  time is entered
			     the next  command	in
			     the  history  list is
			     accessed.

	      Fetch the least recent (oldest) his‐
	      tory line.

	      Fetch  the  most	recent	(youngest)
	      history line.

	      Reverse search history for a  previ‐
	      ous command line containing
			     string.  If a parame‐
			     ter of zero is given,
			     the  search  is  for‐
			     ward.  string is ter‐
			     minated  by  a return
			     or	   newline.	If
			     string is preceded by
			     a	the  matched  line
			     must    begin    with
			     string.  If string is
			     omitted,	the   next
			     command line contain‐
			     ing  the  most recent
			     string  is	 accessed.
			     In	  this	 case,	 a
			     parameter	 of   zero
			     reverses  the  direc‐
			     tion of the search.

	      Execute the current line
			     and  fetch	 the  next
			     line relative to cur‐
			     rent  line	 from  the
			     history file.

	      Define a numeric parameter.
			     The  digits are taken
			     as a parameter to the
			     next   command.   The
			     commands that  accept
			     a	  parameter    are
			     erase, and

	      Your alias list is searched  for	an
	      alias by the name
			     (underscore-letter).
			     If an alias  of  this
			     name  is defined, its
			     value is inserted	on
			     the    input   queue.
			     This letter must  not
			     be	 one  of the above
			     metafunctions.

	      The last word of the  previous  com‐
	      mand is inserted on the line.
			     If	  preceded   by	 a
			     numeric	parameter,
			     the   value  of  this
			     parameter	determines
			     which  word to insert
			     rather than the  last
			     word.

	      Same as

	      Attempt  file name generation on the
	      current word.

	      File name completion
			     (meta-escape).
			     Replaces  the current
			     word with the longest
			     common  prefix of all
			     file  names  matching
			     the current word with
			     an asterisk appended.
			     If	  the	match	is
			     unique, a is appended
			     if	  the  file  is	 a
			     directory and a space
			     is	 appended  if  the
			     file is not a  direc‐
			     tory.

	      List  files  matching  current  word
	      pattern
			     as	 if  an	  asterisk
			     were appended.

	      Multiply	parameter  of next command
	      by 4.

	      Escape next character.
			     Editing	characters
			     and your erase, kill,
			     and interrupt charac‐
			     ters  may	be entered
			     in a command line	or
			     in	 a  search string,
			     if preceded by a  The
			     removes	the   next
			     character's   editing
			     features (if any).

	      Display version of the shell.

	      Insert a	     at	 the  beginning of
			     the line and  execute
			     it.   This	 causes	 a
			     comment	 to	be
			     inserted  in the his‐
			     tory file.

   vi Editing Mode
       The editor starts in insert mode	 until	an
       escape (ESC) is received.  This puts you in
       control mode in which you can move the cur‐
       sor and perform editing commands.  A return
       in either mode sends the line.

       Most control commands  accept  an  optional
       repeat count prior to the command.

       In mode on most systems, canonical process‐
       ing is initially enabled and the command is
       echoed  again  if the speed is 1200 baud or
       greater and contains  any  control  charac‐
       ters,  or  if  less  than  one  second  has
       elapsed since the prompt was printed.   The
       escape (ESC) character terminates canonical
       processing for the remainder of the command
       and  you	 can then modify the command line.
       This scheme has the advantages of canonical
       processing  with	 the  typeahead echoing of
       raw mode.

       Setting the option always disables  canoni‐
       cal  processing on the terminal.	 This mode
       is implicit for systems that do not support
       two  alternate  end-of-line delimiters, and
       may be helpful for certain  terminals.	By
       default, the editor is in insert mode.

	      erase	     Delete	  previous
			     inserted	character.
			     The  erase	 character
			     is	    user-definable
			     with  the command; it
			     is usually set to The
			     system default is

	      kill	     Delete   all  current
			     inserted  characters.
			     The kill character is
			     user-definable   with
			     the  command;  it	is
			     usually set to or The
			     system default is

	      Escape the next
			     erase or kill charac‐
			     ter.

	      eof	     Terminate	the  shell
			     if	 the  current line
			     is	 null.	 The   eof
			     character	 is  user-
			     definable	with   the
			     command;  it  is usu‐
			     ally set to The  sys‐
			     tem default is

	      Escape next character.
			     Editing	characters
			     and  erase	 or   kill
			     characters	  may	be
			     entered in a  command
			     line  or  in a search
			     string if preceded by
			     a	which  removes the
			     next      character's
			     editing  features (if
			     any).

	      Delete the previous  blank-separated
	      word.
       These commands move the cursor.	The use of
       count causes a repetition  of  the  command
       the cited number of times.

	      Cursor  forward  (right) one charac‐
	      ter.

	      Cursor  forward	one   alphanumeric
	      word.

	      Cursor  forward  to the beginning of
	      the next word that follows a blank.

	      Cursor forward to	 the  end  of  the
	      word.

	      Cursor forward to end of the current
	      blank-delimited word.

	      Cursor backward (left)  one  charac‐
	      ter.

	      Cursor backward one word.

	      Cursor  backward to preceding blank-
	      separated word.

	      Cursor to column
			     count.  Default is 1.

	      Find the next character
			     c	in   the   current
			     line.

	      Find the previous character
			     c	 in   the  current
			     line.

	      Equivalent to  followed by

	      Equivalent to  followed by

	      Repeat  the  last	  single-character
	      find command,
			     or

	      Reverses	the  last single character
	      find command.

	      Cursor to start of line.

	      Cursor to first  nonblank	 character
	      in line.

	      Cursor to end of line.
       These  commands access your command history
       file.

	      Fetch previous command.
			     Each time is entered,
			     the next earlier com‐
			     mand in  the  history
			     list is accessed.

	      Equivalent to

	      Fetch next command.
			     Each time is entered,
			     the next  later  com‐
			     mand  in  the history
			     list is accessed.

	      Equivalent to

	      The command number
			     count   is	  fetched.
			     The  default  is  the
			     first command in  the
			     history list.

	      Search  backward through history for
	      a previous command containing
			     string.   string	is
			     terminated	   by	 a
			     return  or	  newline.
			     If string is preceded
			     by a the matched line
			     must    begin    with
			     string.  If string is
			     null,   the  previous
			     string is used.

	      Same as	     but  search  in   the
			     forward direction.

	      Search  for  next	 match of the last
	      pattern to the
			     or commands.

	      Search for next match  of	 the  last
	      pattern to
			     or	  but  in  reverse
			     direction.
       These commands will modify the line.

	      Enter insert mode after the  current
	      character.

	      Append text to the end of the line.
			     Equivalent to

	      Move cursor forward to
	      the character position
	      specified by
			     motion,
			     delet‐
			     ing all
			     charac‐
			     ters
			     between
			     the
			     origi‐
			     nal
			     cursor
			     posi‐
			     tion
			     and the
			     new
			     posi‐
			     tion,
			     and
			     enter
			     insert
			     mode.
			     If
			     motion
			     is	 the
			     entire
			     line is
			     deleted.

	      Delete  from  the cur‐
	      rent character through
	      the end of line
			     and
			     enter
			     insert
			     mode.
			     Equiva‐
			     lent to

	      Equivalent to

	      Move
	      cursor
	      to   the
	      charac‐
	      ter
	      position
	      speci‐
	      fied by	     motion,
			     delet‐
			     ing
			     all
			     char‐
			     ac‐
			     ters
			     between
			     the
			     orig‐
			     i‐
			     nal
			     cur‐
			     sor
			     posi‐
			     tion
			     and
			     the
			     new
			     posi‐
			     tion.
			     If
			     motion
			     is
			     the
			     entire
			     line
			     will
			     be
			     deleted.

	      Delete
	      from the
	      current
	      charac‐
	      ter
	      through
	      the  end
	      of line.	     Equiv‐
			     a‐
			     lent
			     to

	      Enter
	      insert
	      mode
	      before
	      the cur‐
	      rent
	      charac‐
	      ter.

	      Enter
	      insert
	      mode
	      before
	      the
	      begin‐
	      ning  of
	      the
	      line.	     Equiv‐
			     a‐
			     lent
			     to
			     the
			     two-
			     char‐
			     ac‐
			     ter
			     sequence

	      Insert
	      the pre‐
	      vious
	      text
	      modifi‐
	      cation
	      before
	      the cur‐
	      sor.

	      Insert
	      the pre‐
	      vious
	      text
	      modifi‐
	      cation
	      after
	      the cur‐
	      sor.

	      Enter
	      insert
	      mode and
	      replace
	      charac‐
	      ters  on
	      the
	      screen	     with
			     char‐
			     ac‐
			     ters
			     you
			     type,
			     over‐
			     lay
			     fash‐
			     ion.

	      Replace
	      the cur‐
	      rent
	      charac‐
	      ter with	     c.

	      Delete
	      the cur‐
	      rent
	      charac‐
	      ter.

	      Delete
	      the pre‐
	      ceding
	      charac‐
	      ter.

	      Repeat
	      the pre‐
	      vious
	      text
	      modifi‐
	      cation
	      command.

	      Invert
	      the case
	      of   the
	      current
	      charac‐
	      ter  and
	      advance
	      the cur‐
	      sor.

	      Append
	      the	     count
			     word
			     of
			     the
			     pre‐
			     vi‐
			     ous
			     com‐
			     mand
			     at
			     the
			     cur‐
			     rent
			     cur‐
			     sor
			     loca‐
			     tion
			     and
			     enter
			     insert
			     mode
			     at
			     the
			     end
			     of
			     the
			     appended
			     text.
			     The
			     last
			     word
			     is
			     used
			     if
			     count
			     is
			     omit‐
			     ted.

	      Append
	      an	     to
			     the
			     cur‐
			     rent
			     word
			     and
			     attempt
			     file
			     name
			     gen‐
			     er‐
			     a‐
			     tion.
			     If
			     no
			     match
			     is
			     found,
			     ring
			     the
			     bell.
			     If
			     a
			     match
			     is
			     found,
			     replace
			     the
			     word
			     with
			     the
			     match‐
			     ing
			     string
			     of
			     file
			     names
			     and
			     enter
			     insert
			     mode.

	      escape

	      Attempt
	      file
	      name
	      comple‐
	      tion  on
	      the cur‐
	      rent
	      word.	     Replace
			     the
			     cur‐
			     rent
			     word
			     with
			     the
			     long‐
			     est
			     com‐
			     mon
			     pre‐
			     fix
			     of
			     all
			     file
			     names
			     match‐
			     ing
			     the
			     cur‐
			     rent
			     word
			     with
			     an
			     aster‐
			     isk
			     appended.
			     If
			     the
			     match
			     is
			     unique,
			     append
			     a
			     if
			     the
			     file
			     is
			     a
			     direc‐
			     tory
			     or
			     append
			     a
			     space
			     if
			     the
			     file
			     is
			     not
			     a
			     direc‐
			     tory.

	      Yank
	      cur‐
	      rent
	      char‐
	      ac‐
	      ter
	      through
	      char‐
	      ac‐
	      ter
	      that	     motion
			     would
			     move
			     the
			     cur‐
			     sor
			     to
			     and
			     put
			     them
			     into
			     the
			     delete
			     buf‐
			     fer.
			     The
			     text
			     and
			     cur‐
			     sor
			     are
			     unchanged.

	      Yank
	      from
	      cur‐
	      rent
	      posi‐
	      tion
	      to
	      end
	      of
	      line.	     Equiv‐
			     a‐
			     lent
			     to

	      Undo
	      the
	      last
	      text-
	      mod‐
	      i‐
	      fy‐
	      ing
	      com‐
	      mand.

	      Undo
	      all
	      the
	      text-
	      mod‐
	      i‐
	      fy‐
	      ing
	      com‐
	      mands
	      per‐
	      formed
	      on
	      the
	      line.

	      Exe‐
	      cute
	      the
	      com‐
	      mand	     in
			     the
			     input
			     buf‐
			     fer.
			     If
			     count
			     is
			     omit‐
			     ted,
			     the
			     cur‐
			     rent
			     line
			     is
			     used.
			     This
			     exe‐
			     cutes
			     an
			     edi‐
			     tor
			     with
			     the
			     cur‐
			     rent
			     line
			     as
			     the
			     input
			     "file".
			     When
			     you
			     exit
			     from
			     the
			     edi‐
			     tor,
			     the
			     result
			     is
			     exe‐
			     cuted.

	      Line
	      feed
	      and
	      print
	      cur‐
	      rent
	      line.

	      Exe‐
	      cute
	      the
	      cur‐
	      rent
	      line,
	      regard‐
	      less
	      of
	      mode	     (new‐
			     line).

	      Exe‐
	      cute
	      the
	      cur‐
	      rent
	      line,
	      regard‐
	      less
	      of
	      mode	     (return).

	      Insert
	      a		     at
			     the
			     begin‐
			     ning
			     of
			     the
			     cur‐
			     rent
			     line
			     and
			     after
			     each
			     embed‐
			     ded
			     new‐
			     line,
			     and
			     exe‐
			     cute
			     the
			     line.
			     Use‐
			     ful
			     for
			     insert‐
			     ing
			     the
			     cur‐
			     rent
			     com‐
			     mand
			     line
			     in
			     the
			     his‐
			     tory
			     list
			     with‐
			     out
			     exe‐
			     cut‐
			     ing
			     it.

	      List
	      the
	      file
	      names
	      that
	      match
	      the
	      cur‐
	      rent
	      word	     if
			     an
			     aster‐
			     isk
			     were
			     appended
			     to
			     it.

	      Search
	      your
	      alias
	      list
	      for
	      an
	      alias
	      with
	      the
	      name	     (under‐
			     score
			     let‐
			     ter).
			     If
			     an
			     alias
			     of
			     this
			     name
			     is
			     defined,
			     its
			     value
			     is
			     exe‐
			     cuted
			     as
			     a
			     com‐
			     mand
			     sequence
			     on
			     the
			     cur‐
			     rent
			     line.
			     This
			     pro‐
			     vides
			     a
			     sim‐
			     ple
			     macro
			     capa‐
			     bil‐
			     ity.

EXTERNAL
       INFLU‐
       ENCES

       For
       infor‐
       ma‐
       tion
       about
       the
       UNIX
       Stan‐
       dard
       envi‐
       ron‐
       ment,
       see
       stan‐
       dards(5).

   Envi‐
       ron‐
       ment
       Vari‐
       ables
       deter‐
       mines
       the
       col‐
       lat‐
       ing
       sequence
       used
       in
       eval‐
       u‐
       at‐
       ing
       pat‐
       tern
       match‐
       ing
       nota‐
       tion
       for
       file
       name
       gen‐
       er‐
       a‐
       tion.
       If
       it
       is
       not
       defined
       or
       is
       empty,
       it
       defaults
       to
       the
       value
       of

       deter‐
       mines
       the
       clas‐
       si‐
       fi‐
       ca‐
       tion
       of
       char‐
       ac‐
       ters
       as
       let‐
       ters,
       and
       the
       char‐
       ac‐
       ters
       matched
       by
       char‐
       ac‐
       ter
       class
       expres‐
       sions
       in
       pat‐
       tern
       match‐
       ing
       nota‐
       tion.
       If
       it
       is
       not
       defined
       or
       is
       empty,
       it
       defaults
       to
       the
       value
       of

       If
       is
       not
       defined
       or
       is
       empty,
       it
       defaults
       to
       (see
       lang(5)).

       If
       any
       inter‐
       na‐
       tion‐
       al‐
       iza‐
       tion
       vari‐
       able
       con‐
       tains
       an
       invalid
       value,
       they
       all
       default
       to
       (see
       env‐
       i‐
       ron(5)).

   Inter‐
       na‐
       tional
       Code
       Set
       Sup‐
       port
       Sin‐
       gle-
       and
       multi‐
       byte
       char‐
       ac‐
       ter
       code
       sets
       are
       sup‐
       ported.

RETURN
       VALUE

       Errors
       detected
       by
       the
       shell,
       such
       as
       syn‐
       tax
       errors,
       cause
       the
       shell
       to
       return
       a
       nonzero
       exit
       sta‐
       tus.
       Oth‐
       er‐
       wise,
       the
       shell
       returns
       the
       exit
       sta‐
       tus
       of
       the
       last
       com‐
       mand
       exe‐
       cuted.
       See
       also
       the
       spe‐
       cial
       com‐
       mand.

       If
       the
       shell
       is
       being
       used
       non‐
       in‐
       ter‐
       ac‐
       tively,
       the
       exe‐
       cu‐
       tion
       of
       the
       shell
       file
       is
       aban‐
       doned.
       Run‐
       time
       errors
       detected
       by
       the
       shell
       are
       reported
       by
       print‐
       ing
       the
       com‐
       mand
       or
       func‐
       tion
       name
       and
       the
       error
       con‐
       di‐
       tion.
       If
       the
       line
       num‐
       ber
       on
       which
       the
       error
       occurred
       is
       greater
       than
       one,
       the
       line
       num‐
       ber
       is
       also
       printed
       in
       brack‐
       ets
       after
       the
       com‐
       mand
       or
       func‐
       tion
       name.

WARNINGS

       Some
       file
       descrip‐
       tors
       are
       used
       inter‐
       nally
       by
       the
       POSIX
       shell.
       For
       HP-
       UX
       releases
       10.10
       and
       beyond,
       file
       descrip‐
       tors
       24
       through
       30
       are
       reserved.
       HP-
       UX
       releases
       10.00
       and
       10.01
       reserve
       descrip‐
       tors
       54
       through
       60.
       Appli‐
       ca‐
       tions
       using
       these
       and
       fork‐
       ing
       a
       sub‐
       shell
       should
       not
       depend
       upon
       them
       sur‐
       viv‐
       ing
       in
       the
       sub‐
       shell
       or
       its
       descen‐
       dants.

       If
       a
       com‐
       mand
       that
       is
       a
       tracked
       alias
       is
       exe‐
       cuted,
       and
       a
       com‐
       mand
       with
       the
       same
       name
       is
       installed
       in
       a
       direc‐
       tory
       in
       the
       search
       path
       before
       the
       direc‐
       tory
       where
       the
       orig‐
       i‐
       nal
       com‐
       mand
       was
       found,
       the
       shell
       will
       con‐
       tinue
       to
       load
       and
       exe‐
       cute
       the
       orig‐
       i‐
       nal
       com‐
       mand.
       Use
       the
       option
       of
       the
       com‐
       mand
       to
       cor‐
       rect
       this
       sit‐
       u‐
       a‐
       tion.

       If
       you
       move
       the
       cur‐
       rent
       direc‐
       tory
       or
       one
       above
       it,
       may
       not
       give
       the
       cor‐
       rect
       response.
       Use
       the
       com‐
       mand
       with
       a
       full
       path
       name
       to
       cor‐
       rect
       this
       sit‐
       u‐
       a‐
       tion.

       Some
       very
       old
       shell
       scripts
       use
       a
       caret
       as
       a
       syn‐
       onym
       for
       the
       pipe
       char‐
       ac‐
       ter
       rec‐
       og‐
       nize
       the
       caret
       as
       a
       pipe
       char‐
       ac‐
       ter.

       If
       a
       com‐
       mand
       is
       piped
       into
       a
       shell
       com‐
       mand,
       all
       vari‐
       ables
       set
       in
       the
       shell
       com‐
       mand
       are
       lost
       when
       the
       com‐
       mand
       com‐
       pletes.

       Using
       the
       built-
       in
       com‐
       mand
       within
       a
       com‐
       pound
       com‐
       mand
       will
       cause
       the
       entire
       com‐
       mand
       to
       dis‐
       ap‐
       pear
       from
       the
       his‐
       tory
       file.

       The
       dot
       spe‐
       cial
       com‐
       mand,
       as
       in
       reads
       the
       entire
       file
       before
       any
       com‐
       mands
       are
       exe‐
       cuted.
       There‐
       fore,
       and
       com‐
       mands
       in
       the
       file
       will
       not
       apply
       to
       any
       func‐
       tions
       defined
       in
       the
       file.

       Traps
       are
       not
       pro‐
       cessed
       while
       the
       shell
       is
       wait‐
       ing
       for
       a
       fore‐
       ground
       job.
       Thus,
       a
       trap
       on
       is
       not
       exe‐
       cuted
       until
       the
       fore‐
       ground
       job
       ter‐
       mi‐
       nates.

       The
       spe‐
       cial
       com‐
       mand
       does
       not
       han‐
       dle
       arrays
       prop‐
       erly.
       Only
       the
       first
       ele‐
       ment
       of
       an
       array
       is
       exported
       to
       the
       envi‐
       ron‐
       ment.

       Back‐
       ground
       pro‐
       cesses
       started
       from
       a
       non‐
       in‐
       ter‐
       ac‐
       tive
       shell
       can‐
       not
       be
       accessed
       with
       job
       con‐
       trol
       com‐
       mands.

       The
       value
       of
       the
       vari‐
       able
       in
       the
       user's
       envi‐
       ron‐
       ment
       affects
       the
       behav‐
       ior
       of
       scripts.

   Col‐
       lat‐
       ing
       Order
       In
       an
       inter‐
       na‐
       tional
       envi‐
       ron‐
       ment,
       char‐
       ac‐
       ter
       order‐
       ing
       is
       deter‐
       mined
       by
       the
       value
       of
       rather
       than
       by
       the
       binary
       order‐
       ing
       of
       char‐
       ac‐
       ter
       val‐
       ues
       in
       the
       machine
       col‐
       lat‐
       ing
       sequence.
       This
       brings
       with
       it
       cer‐
       tain
       atten‐
       dant
       dan‐
       gers,
       par‐
       tic‐
       u‐
       larly
       when
       using
       range
       expres‐
       sions
       in
       file
       name
       gen‐
       er‐
       a‐
       tion
       pat‐
       terns.
       For
       exam‐
       ple,
       the
       com‐
       mand,

       might
       be
       expected
       to
       match
       all
       file
       names
       begin‐
       ning
       with
       a
       low‐
       er‐
       case
       alpha‐
       betic
       char‐
       ac‐
       ter.
       How‐
       ever,
       if
       dic‐
       tio‐
       nary
       order‐
       ing
       is
       spec‐
       i‐
       fied
       by
       it
       would
       also
       match
       file
       names
       begin‐
       ning
       with
       an
       upper‐
       case
       char‐
       ac‐
       ter
       (as
       well
       as
       those
       begin‐
       ning
       with
       accented
       let‐
       ters).
       Con‐
       versely,
       it
       would
       fail
       to
       match
       let‐
       ters
       col‐
       lated
       after
       in
       lan‐
       guages
       such
       as
       Dan‐
       ish
       or
       Nor‐
       we‐
       gian.

       The
       cor‐
       rect
       (and
       safe)
       way
       to
       match
       spe‐
       cific
       char‐
       ac‐
       ter
       classes
       in
       an
       inter‐
       na‐
       tional
       envi‐
       ron‐
       ment
       is
       to
       use
       a
       pat‐
       tern
       (see
       reg‐
       exp(5))
       of
       the
       form:

       This
       uses
       to
       deter‐
       mine
       char‐
       ac‐
       ter
       classes
       and
       works
       pre‐
       dictably
       for
       all
       sup‐
       ported
       lan‐
       guages
       and
       code‐
       sets.
       For
       shell
       scripts
       pro‐
       duced
       on
       non‐
       in‐
       ter‐
       na‐
       tion‐
       al‐
       ized
       sys‐
       tems
       (or
       with‐
       out
       con‐
       sid‐
       er‐
       a‐
       tion
       for
       the
       above
       dan‐
       gers),
       it
       is
       rec‐
       om‐
       mended
       that
       they
       be
       exe‐
       cuted
       in
       a
       non-
       NLS
       envi‐
       ron‐
       ment.
       This
       requires
       that
       and
       so
       on,
       be
       set
       to
       or
       not
       set
       at
       all.

   His‐
       tory
       File
       and
       Locales
       The
       his‐
       tory
       file
       does
       not
       sup‐
       port
       mix‐
       ing
       of
       locales
       in
       the
       same
       file.
       For
       users
       of
       mul‐
       ti‐
       ple
       locales,
       you
       can
       assign
       a
       unique
       his‐
       tory
       file
       for
       each
       locale
       by
       set‐
       ting
       as:

       On
       encoun‐
       ter‐
       ing
       a
       his‐
       tory
       file
       with
       invalid
       char‐
       ac‐
       ters
       for
       the
       cur‐
       rent
       locale
       set‐
       ting,
       the
       shell
       will
       inform
       the
       user
       about
       it
       and
       con‐
       tinue
       pro‐
       cess‐
       ing
       user
       input.
       No
       his‐
       tory
       fea‐
       tures
       will
       be
       avail‐
       able
       to
       the
       user
       in
       such
       a
       ses‐
       sion.
       Restart‐
       ing
       the
       shell
       after
       set‐
       ting
       a
       new
       his‐
       tory
       file
       or
       after
       remov‐
       ing
       the
       cur‐
       rent
       his‐
       tory
       file
       allows
       the
       user
       to
       access
       the
       his‐
       tory
       fea‐
       tures.

   Here-
       Doc‐
       u‐
       ment
       Temp
       Files
       The
       con‐
       tents
       of
       here-
       doc‐
       u‐
       ments
       are
       stored
       in
       tem‐
       po‐
       rary
       files
       named
       Usu‐
       ally,
       these
       tem‐
       po‐
       rary
       files
       are
       removed
       after
       they
       are
       used.
       How‐
       ever,
       due
       to
       design
       lim‐
       i‐
       ta‐
       tions,
       these
       tem‐
       po‐
       rary
       files
       may
       some‐
       times
       con‐
       tinue
       to
       exist
       after
       the
       shell
       exits.
       pid
       is
       the
       process
       ID
       of
       the
       shell.
       num‐
       ber
       is
       a
       sequence
       num‐
       ber
       for
       the
       here-
       doc‐
       u‐
       ment
       files.

AUTHOR
       was
       devel‐
       oped
       by
       AT&T,
       OSF,
       and
       HP.

FILES
       Read
       to
       set
       up
       user's
       cus‐
       tom
       envi‐
       ron‐
       ment
       To
       find
       home
       direc‐
       to‐
       ries
       Read
       to
       set
       up
       sys‐
       tem
       envi‐
       ron‐
       ment
       Secu‐
       rity
       pro‐
       file
       Archived
       exe‐
       cutable,
       espe‐
       cially
       for
       root
       access
       For
       here-
       doc‐
       u‐
       ments
       if			     is
				     not
				     acces‐
				     si‐
				     ble
       Stan‐
       dard
       exe‐
       cutable
       for
       the
       POSIX
       shell
       For
       here-
       doc‐
       u‐
       ments
       if			     is
				     acces‐
				     si‐
				     ble

SEE ALSO

       cat(1),
       cd(1),
       com‐
       mand(1),
       echo(1),
       ed(1),
       env(1),
       getopts(1),
       kill(1),
       ln(1),
       login(1),
       new‐
       grp(1),
       printf(1),
       pwd(1),
       read(1),
       stty(1),
       test(1),
       time(1),
       umask(1),
       vi(1),
       dup(2),
       exec(2),
       fork(2),
       pipe(2),
       stty(2),
       ulimit(2),
       umask(2),
       wait(2),
       rand(3C),
       a.out(4),
       pro‐
       file(4),
       env‐
       i‐
       ron(5),
       lang(5),
       reg‐
       exp(5),
       sig‐
       nal(5),
       stan‐
       dards(5).

STAN‐
       DARDS
       CON‐
       FOR‐
       MANCE

								   sh-posix(1)
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