linux man page for envsubst

ENVSUBST(1)								GNU							       ENVSUBST(1)

NAME
       envsubst - substitutes environment variables in shell format strings

SYNOPSIS
       envsubst [OPTION] [SHELL-FORMAT]

DESCRIPTION
       Substitutes the values of environment variables.

   Operation mode:
       -v, --variables
	      output the variables occurring in SHELL-FORMAT

   Informative output:
       -h, --help
	      display this help and exit

       -V, --version
	      output version information and exit

       In  normal  operation  mode, standard input is copied to standard output, with references to environment variables of the form $VARIABLE or
       ${VARIABLE} being replaced with the corresponding values.  If a SHELL-FORMAT is given, only those environment variables that are referenced
       in SHELL-FORMAT are substituted; otherwise all environment variables references occurring in standard input are substituted.

       When --variables is used, standard input is ignored, and the output consists of the environment variables that are referenced in SHELL-FOR-
       MAT, one per line.

AUTHOR
       Written by Bruno Haible.

REPORTING BUGS
       Report bugs to <bug-gnu-gettext@gnu.org>.

COPYRIGHT
       Copyright (C) 2003-2007 Free Software Foundation, Inc.  License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
       This is free software: you are free to change and redistribute it.  There is NO WARRANTY, to the extent permitted by law.

SEE ALSO
       The full documentation for envsubst is maintained as a Texinfo manual.  If the info and envsubst programs are properly  installed  at  your
       site, the command

	      info envsubst

       should give you access to the complete manual.

GNU gettext-runtime 0.18.1					     June 2010							       ENVSUBST(1)