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ENV(P)			   POSIX Programmer's Manual			ENV(P)

NAME
       env - set the environment for command invocation

SYNOPSIS
       env [-i][name=value]...	[utility [argument...]]

DESCRIPTION
       The env utility shall obtain the current environment, modify it accord‐
       ing to its arguments, then invoke the utility named by the utility  op‐
       erand with the modified environment.

       Optional arguments shall be passed to utility.

       If  no utility operand is specified, the resulting environment shall be
       written to the standard output, with one name= value pair per line.

OPTIONS
       The env utility	shall  conform	to  the	 Base  Definitions  volume  of
       IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines.

       The following options shall be supported:

       -i     Invoke  utility  with  exactly  the environment specified by the
	      arguments; the  inherited	 environment  shall  be	 ignored  com‐
	      pletely.

OPERANDS
       The following operands shall be supported:

       name=value
	      Arguments	 of  the  form	name= value shall modify the execution
	      environment, and shall be placed into the inherited  environment
	      before the utility is invoked.

       utility
	      The  name	 of  the utility to be invoked. If the utility operand
	      names any of the special built-in utilities in Special  Built-In
	      Utilities , the results are undefined.

       argument
	      A string to pass as an argument for the invoked utility.

STDIN
       Not used.

INPUT FILES
       None.

ENVIRONMENT VARIABLES
       The following environment variables shall affect the execution of env:

       LANG   Provide  a  default value for the internationalization variables
	      that are unset or null. (See  the	 Base  Definitions  volume  of
	      IEEE Std 1003.1-2001,  Section  8.2,  Internationalization Vari‐
	      ables for the precedence of internationalization variables  used
	      to determine the values of locale categories.)

       LC_ALL If  set  to a non-empty string value, override the values of all
	      the other internationalization variables.

       LC_CTYPE
	      Determine the locale for	the  interpretation  of	 sequences  of
	      bytes  of	 text  data as characters (for example, single-byte as
	      opposed to multi-byte characters in arguments).

       LC_MESSAGES
	      Determine the locale that should be used to  affect  the	format
	      and contents of diagnostic messages written to standard error.

       NLSPATH
	      Determine the location of message catalogs for the processing of
	      LC_MESSAGES .

       PATH   Determine the location of the utility, as described in the  Base
	      Definitions  volume of IEEE Std 1003.1-2001, Chapter 8, Environ‐
	      ment Variables. If PATH is specified as a name= value operand to
	      env, the value given shall be used in the search for utility.

ASYNCHRONOUS EVENTS
       Default.

STDOUT
       If  no  utility	operand	 is  specified,	 each  name= value pair in the
       resulting environment shall be written in the form:

	      "%s=%s\n", <name>, <value>

       If the utility operand is specified, the env utility shall not write to
       standard output.

STDERR
       The standard error shall be used only for diagnostic messages.

OUTPUT FILES
       None.

EXTENDED DESCRIPTION
       None.

EXIT STATUS
       If  utility is invoked, the exit status of env shall be the exit status
       of utility; otherwise, the env utility shall exit with one of the  fol‐
       lowing values:

	   0  The env utility completed successfully.

       1-125  An error occurred in the env utility.

	 126  The  utility  specified  by  utility  was found but could not be
	      invoked.

	 127  The utility specified by utility could not be found.

CONSEQUENCES OF ERRORS
       Default.

       The following sections are informative.

APPLICATION USAGE
       The command, env, nice, nohup, time,  and  xargs	 utilities  have  been
       specified  to use exit code 127 if an error occurs so that applications
       can distinguish "failure to  find  a  utility"  from  "invoked  utility
       exited  with  an error indication". The value 127 was chosen because it
       is not commonly used for other meanings; most utilities use small  val‐
       ues  for "normal error conditions" and the values above 128 can be con‐
       fused with termination due to receipt of a signal. The  value  126  was
       chosen in a similar manner to indicate that the utility could be found,
       but not invoked. Some scripts produce meaningful error messages differ‐
       entiating the 126 and 127 cases. The distinction between exit codes 126
       and 127 is based on KornShell practice that uses 127 when all  attempts
       to  exec	 the utility fail with [ENOENT], and uses 126 when any attempt
       to exec the utility fails for any other reason.

       Historical implementations of the env utility use the execvp() or  exe‐
       clp()   functions   defined   in	  the	System	Interfaces  volume  of
       IEEE Std 1003.1-2001 to invoke the  specified  utility;	this  provides
       better  performance  and	 keeps	users from having to escape characters
       with special meaning to the shell. Therefore, shell functions,  special
       built-ins,  and	built-ins  that are only provided by the shell are not
       found.

EXAMPLES
       The following command:

	      env -i PATH=/mybin mygrep xyz myfile

       invokes the command mygrep with a new PATH value as the only  entry  in
       its  environment.  In  this  case, PATH is used to locate mygrep, which
       then must reside in /mybin.

RATIONALE
       As with all other utilities that invoke other utilities, this volume of
       IEEE Std 1003.1-2001  only specifies what env does with standard input,
       standard output, standard error, input files, and output	 files.	 If  a
       utility	is  executed,  it  is  not constrained by the specification of
       input and output by env.

       The -i option was added to allow the functionality of the  withdrawn  -
       option in a manner compatible with the Utility Syntax Guidelines.

       Some  have  suggested  that  env	 is redundant since the same effect is
       achieved by:

	      name=value ... utility [ argument ... ]

       The example is equivalent to env when an environment variable is	 being
       added  to  the environment of the command, but not when the environment
       is being set to the given value. The env utility also  writes  out  the
       current	environment  if invoked without arguments. There is sufficient
       functionality beyond what the example provides to justify inclusion  of
       env.

FUTURE DIRECTIONS
       None.

SEE ALSO
       Parameters and Variables , Special Built-In Utilities

COPYRIGHT
       Portions	 of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       --  Portable  Operating	System	Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003	by  the	 Institute  of
       Electrical  and	Electronics  Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE and
       The  Open Group Standard, the original IEEE and The Open Group Standard
       is the referee document. The original Standard can be  obtained	online
       at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group		     2003				ENV(P)
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