tclvars man page on OpenDarwin

Man page or keyword search:  
man Server   3202 pages
apropos Keyword Search (all sections)
Output format
OpenDarwin logo
[printable version]

tclvars(n)		     Tcl Built-In Commands		    tclvars(n)

______________________________________________________________________________

NAME
       tclvars - Variables used by Tcl
_________________________________________________________________

DESCRIPTION
       The following global variables are created and managed automatically by
       the Tcl library.	 Except where noted below, these variables should nor‐
       mally  be  treated  as  read-only  by  application-specific code and by
       users.

       env    This variable is maintained by Tcl as an	array  whose  elements
	      are  the environment variables for the process.  Reading an ele‐
	      ment will return the  value  of  the  corresponding  environment
	      variable.	  Setting an element of the array will modify the cor‐
	      responding environment variable  or  create  a  new  one	if  it
	      doesn't  already exist.  Unsetting an element of env will remove
	      the corresponding environment  variable.	 Changes  to  the  env
	      array will affect the environment passed to children by commands
	      like exec.  If the entire env array is unset then Tcl will  stop
	      monitoring  env  accesses	 and will not update environment vari‐
	      ables.
	      Under Windows, the environment variables PATH and COMSPEC in any │
	      capitalization  are  converted automatically to upper case.  For │
	      instance, the PATH variable could be exported by	the  operating │
	      system  as ``path'', ``Path'', ``PaTh'', etc., causing otherwise │
	      simple Tcl code to have to  support  many	 special  cases.   All │
	      other  environment  variables  inherited by Tcl are left unmodi‐ │
	      fied.  Setting an env array variable to blank  is	 the  same  as │
	      unsetting	 it  as this is the behavior of the underlying Windows │
	      OS.  It should be noted that relying on an  existing  and	 empty │
	      environment  variable  won't  work on windows and is discouraged │
	      for cross-platform usage.
	      On the Macintosh, the environment variable is constructed by Tcl
	      as no global environment variable exists.	 The environment vari‐
	      ables that are created for Tcl include:

	      LOGIN  This holds the Chooser name of the Macintosh.

	      USER   This also holds the Chooser name of the Macintosh.

	      SYS_FOLDER
		     The path to the system directory.

	      APPLE_M_FOLDER
		     The path to the Apple Menu directory.

	      CP_FOLDER
		     The path to the control panels directory.

	      DESK_FOLDER
		     The path to the desk top directory.

	      EXT_FOLDER
		     The path to the system extensions directory.

	      PREF_FOLDER
		     The path to the preferences directory.

	      PRINT_MON_FOLDER
		     The path to the print monitor directory.

	      SHARED_TRASH_FOLDER
		     The path to the network trash directory.

	      TRASH_FOLDER
		     The path to the trash directory.

	      START_UP_FOLDER
		     The path to the start up directory.

	      HOME   The path to the application's default directory.

	      You can also create your own environment variables for the  Mac‐
	      intosh.	A  file named  Tcl Environment Variables may be placed
	      in the preferences folder in the Mac system folder.   Each  line
	      of this file should be of the form VAR_NAME=var_data.

	      The  last	 alternative  is  to  place environment variables in a
	      'STR#' resource named Tcl Environment Variables of the  applica‐
	      tion.  This is considered a little more ``Mac like'' than a Unix
	      style Environment Variable  file.	  Each	entry  in  the	'STR#'
	      resource	has  the  same	format as above.  The source code file
	      tclMacEnv.c contains the implementation of the  env  mechanisms.
	      This  file  contains  many #define's that allow customization of
	      the env mechanisms to fit your applications needs.

       errorCode
	      After an error has occurred, this variable will be set  to  hold
	      additional information about the error in a form that is easy to
	      process with programs.  errorCode consists of a  Tcl  list  with
	      one  or more elements.  The first element of the list identifies
	      a general class of errors, and determines the format of the rest
	      of  the  list.   The following formats for errorCode are used by
	      the Tcl core; individual applications may define additional for‐
	      mats.

	      ARITH code msg
		     This format is used when an arithmetic error occurs (e.g.
		     an attempt to divide by zero in the expr command).	  Code
		     identifies	 the  precise  error and msg provides a human-
		     readable description of the error.	 Code will  be	either
		     DIVZERO (for an attempt to divide by zero), DOMAIN (if an
		     argument is outside the domain of	a  function,  such  as
		     acos(-3)),	 IOVERFLOW  (for  integer  overflow), OVERFLOW
		     (for a floating-point overflow), or UNKNOWN (if the cause
		     of the error cannot be determined).

	      CHILDKILLED pid sigName msg
		     This  format is used when a child process has been killed
		     because of a signal.  The	second	element	 of  errorCode
		     will be the process's identifier (in decimal).  The third
		     element will be the symbolic  name	 of  the  signal  that
		     caused  the  process  to terminate; it will be one of the
		     names from the include file signal.h,  such  as  SIGPIPE.
		     The fourth element will be a short human-readable message
		     describing the signal, such as ``write on	pipe  with  no
		     readers'' for SIGPIPE.

	      CHILDSTATUS pid code
		     This  format is used when a child process has exited with
		     a non-zero exit status.  The second element of  errorCode
		     will  be  the  process's  identifier (in decimal) and the
		     third element will be  the	 exit  code  returned  by  the
		     process (also in decimal).

	      CHILDSUSP pid sigName msg
		     This  format  is  used when a child process has been sus‐
		     pended because of a signal.  The second element of error‐
		     Code  will	 be the process's identifier, in decimal.  The
		     third element will be the symbolic	 name  of  the	signal
		     that  caused  the process to suspend; this will be one of
		     the names from the include file signal.h, such  as	 SIGT‐
		     TIN.   The	 fourth element will be a short human-readable
		     message describing the signal, such as  ``background  tty
		     read'' for SIGTTIN.

	      NONE   This format is used for errors where no additional infor‐
		     mation is available for  an  error	 besides  the  message
		     returned  with  the error.	 In these cases errorCode will
		     consist of a list containing a single element whose  con‐
		     tents are NONE.

	      POSIX errName msg
		     If	 the  first  element  of  errorCode is POSIX, then the
		     error occurred during a POSIX kernel  call.   The	second
		     element of the list will contain the symbolic name of the
		     error that occurred, such as ENOENT; this will be one  of
		     the  values  defined  in  the  include file errno.h.  The
		     third element of the list will be a  human-readable  mes‐
		     sage  corresponding to errName, such as ``no such file or
		     directory'' for the ENOENT case.

	      To set errorCode, applications  should  use  library  procedures
	      such  as Tcl_SetErrorCode and Tcl_PosixError, or they may invoke
	      the error command.  If one of these methods  hasn't  been	 used,
	      then  the	 Tcl interpreter will reset the variable to NONE after
	      the next error.

       errorInfo
	      After an error has occurred, this string	will  contain  one  or
	      more lines identifying the Tcl commands and procedures that were
	      being executed when the most recent error	 occurred.   Its  con‐
	      tents  take the form of a stack trace showing the various nested
	      Tcl commands that had been invoked at the time of the error.

       tcl_library
	      This variable holds the name of a directory containing the  sys‐
	      tem library of Tcl scripts, such as those used for auto-loading.
	      The value of this variable is returned by the info library  com‐
	      mand.   See  the library manual entry for details of the facili‐
	      ties provided by the Tcl script library.	Normally each applica‐
	      tion  or	package	 will have its own application-specific script
	      library in addition to the Tcl script library; each  application
	      should  set  a  global  variable	with  a name like $app_library
	      (where app is the application's name) to hold the	 network  file
	      name  for	 that  application's  library  directory.  The initial
	      value of tcl_library is set when an interpreter  is  created  by
	      searching	 several different directories until one is found that
	      contains an appropriate Tcl startup script.  If the  TCL_LIBRARY
	      environment  variable  exists,  then  the	 directory it names is
	      checked first.  If TCL_LIBRARY isn't set or doesn't refer to  an
	      appropriate directory, then Tcl checks several other directories
	      based on a compiled-in default location,	the  location  of  the
	      binary  containing  the  application,  and  the  current working
	      directory.

       tcl_patchLevel
	      When an interpreter is created Tcl initializes this variable  to
	      hold  a  string  giving the current patch level for Tcl, such as
	      7.3p2 for Tcl 7.3 with the first two official patches, or	 7.4b4
	      for the fourth beta release of Tcl 7.4.  The value of this vari‐
	      able is returned by the info patchlevel command.

       tcl_pkgPath							       │
	      This variable holds a list of directories indicating where pack‐ │
	      ages  are	 normally  installed.	It is not used on Windows.  It │
	      typically contains either one or two entries; if it contains two │
	      entries,	the  first is normally a directory for platform-depen‐ │
	      dent packages (e.g., shared library binaries) and the second  is │
	      normally	a  directory  for platform-independent packages (e.g., │
	      script files). Typically a package is installed as  a  subdirec‐ │
	      tory  of	one of the entries in $tcl_pkgPath. The directories in │
	      $tcl_pkgPath are included by default in the auto_path  variable, │
	      so  they	and  their  immediate subdirectories are automatically │
	      searched for packages during package  require  commands.	 Note: │
	      tcl_pkgPath  it  not intended to be modified by the application. │
	      Its value is added to auto_path at startup; changes to  tcl_pkg‐ │
	      Path  are not reflected in auto_path.  If you want Tcl to search │
	      additional directories for packages you should add the names  of │
	      those directories to auto_path, not tcl_pkgPath.

       tcl_platform
	      This  is an associative array whose elements contain information
	      about the platform on which the application is running, such  as
	      the  name	 of  the operating system, its current release number,
	      and the machine's instruction set.  The  elements	 listed	 below
	      will  always be defined, but they may have empty strings as val‐
	      ues if Tcl couldn't retrieve any relevant information.  In addi‐
	      tion,  extensions	 and applications may add additional values to
	      the array.  The predefined elements are:

	      byteOrder							       │
		     The native byte order of this machine:  either  littleEn‐ │
		     dian or bigEndian.

	      debug  If	 this  variable	 exists, then the interpreter was com‐
		     piled with debugging symbols enabled.  This variable will
		     only  exist  on  Windows so extension writers can specify
		     which package to load depending on the C run-time library
		     that is loaded.

	      machine
		     The  instruction  set  executed  by this machine, such as
		     intel, PPC, 68k, or sun4m.	 On UNIX machines, this is the
		     value returned by uname -m.

	      os     The name of the operating system running on this machine,
		     such as Windows 95, Windows NT, MacOS, or SunOS.  On UNIX
		     machines,	this  is  the  value returned by uname -s.  On
		     Windows 95 and Windows 98, the  value  returned  will  be
		     Windows  95  to provide better backwards compatibility to
		     Windows 95; to distinguish between	 the  two,  check  the
		     osVersion.

	      osVersion
		     The  version  number  for the operating system running on
		     this machine.   On	 UNIX  machines,  this	is  the	 value
		     returned by uname -r.  On Windows 95, the version will be
		     4.0; on Windows 98, the version will be 4.10.

	      platform
		     Either windows, macintosh, or unix.  This identifies  the
		     general operating environment of the machine.

	      threaded
		     If	 this  variable	 exists, then the interpreter was com‐
		     piled with threads enabled.

	      user   This identifies the  current  user	 based	on  the	 login
		     information  available  on the platform.  This comes from
		     the USER or LOGNAME environment variable on Unix, and the
		     value from GetUserName on Windows and Macintosh.

	      wordSize
		     This  gives  the size of the native-machine word in bytes │
		     (strictly,	 it  is	 same  as  the	result	of  evaluating │
		     sizeof(long) in C.)

       tcl_precision
	      This  variable  controls	the  number of digits to generate when │
	      converting floating-point values to strings.  It defaults to 12. │
	      17  digits  is  ``perfect''  for	IEEE floating-point in that it │
	      allows double-precision values to be converted  to  strings  and │
	      back  to	binary with no loss of information.  However, using 17 │
	      digits prevents any rounding, which produces longer, less	 intu‐ │
	      itive results.  For example, expr 1.4 returns 1.3999999999999999 │
	      with tcl_precision set to 17, vs. 1.4 if tcl_precision is 12.    │
	      All interpreters in  a  process  share  a	 single	 tcl_precision │
	      value:  changing	it  in	one  interpreter will affect all other │
	      interpreters  as	well.	However,  safe	interpreters  are  not │
	      allowed to modify the variable.				       │

       tcl_rcFileName
	      This variable is used during initialization to indicate the name
	      of a user-specific startup file.	If it is set  by  application-
	      specific	initialization,	 then  the Tcl startup code will check
	      for the existence of this file and source it if it exists.   For
	      example,	for wish the variable is set to ~/.wishrc for Unix and
	      ~/wishrc.tcl for Windows.

       tcl_rcRsrcName
	      This variable is only used on Macintosh systems.	 The  variable
	      is  used	during	initialization to indicate the name of a user-
	      specific TEXT resource located in the application	 or  extension
	      resource	forks.	 If it is set by application-specific initial‐
	      ization, then the Tcl startup code will check for the  existence
	      of  this	resource and source it if it exists.  For example, the
	      Macintosh wish application has the variable is set to tclshrc.

       tcl_traceCompile
	      The value of this variable can be set to control how much	 trac‐
	      ing  information	is  displayed during bytecode compilation.  By
	      default, tcl_traceCompile is zero and  no	 information  is  dis‐
	      played.  Setting tcl_traceCompile to 1 generates a one line sum‐
	      mary in stdout whenever a procedure or top level command is com‐
	      piled.   Setting	it to 2 generates a detailed listing in stdout
	      of the bytecode instructions emitted during  every  compilation.
	      This variable is useful in tracking down suspected problems with
	      the Tcl compiler.	 It is also occasionally useful when  convert‐
	      ing existing code to use Tcl8.0.

	      This  variable and functionality only exist if TCL_COMPILE_DEBUG
	      was defined during Tcl's compilation.

       tcl_traceExec
	      The value of this variable can be set to control how much	 trac‐
	      ing  information	is  displayed  during  bytecode execution.  By
	      default, tcl_traceExec is zero and no information is  displayed.
	      Setting  tcl_traceExec to 1 generates a one line trace in stdout
	      on each call to a Tcl procedure.	Setting it to  2  generates  a
	      line of output whenever any Tcl command is invoked that contains
	      the name of the command and its arguments.  Setting it to 3 pro‐
	      duces  a	detailed  trace	 showing  the result of executing each
	      bytecode instruction.  Note that when tcl_traceExec is 2	or  3,
	      commands	such  as set and incr that have been entirely replaced
	      by a sequence of bytecode instructions are not  shown.   Setting
	      this variable is useful in tracking down suspected problems with
	      the bytecode compiler and interpreter.  It is also  occasionally
	      useful when converting code to use Tcl8.0.

	      This  variable and functionality only exist if TCL_COMPILE_DEBUG
	      was defined during Tcl's compilation.

       tcl_wordchars
	      The value of this variable is a regular expression that  can  be
	      set  to  control	what  are  considered ``word'' characters, for
	      instances like selecting a word by double-clicking  in  text  in
	      Tk.   It	is platform dependent.	On Windows, it defaults to \S,
	      meaning anything but a Unicode space  character.	 Otherwise  it
	      defaults	to  \w,	 which	is any Unicode word character (number,
	      letter, or underscore).

       tcl_nonwordchars
	      The value of this variable is a regular expression that  can  be
	      set  to control what are considered ``non-word'' characters, for
	      instances like selecting a word by double-clicking  in  text  in
	      Tk.   It	is platform dependent.	On Windows, it defaults to \s,
	      meaning any Unicode space character.  Otherwise it  defaults  to
	      \W, which is anything but a Unicode word character (number, let‐
	      ter, or underscore).

       tcl_version
	      When an interpreter is created Tcl initializes this variable  to
	      hold the version number for this version of Tcl in the form x.y.
	      Changes to x represent major changes with probable incompatibil‐
	      ities  and  changes  to  y  represent small enhancements and bug
	      fixes that retain backward compatibility.	  The  value  of  this
	      variable is returned by the info tclversion command.

SEE ALSO
       eval(n)

KEYWORDS
       arithmetic,  bytecode,  compiler, error, environment, POSIX, precision,
       subprocess, variables

Tcl				      8.0			    tclvars(n)
[top]

List of man pages available for OpenDarwin

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net