| envsubst - substitutes environment variables in shell format strings | 
| envsubst [OPTION] [SHELL-FORMAT] | 
| 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-FORMAT, one per line. | 
| Written by Bruno Haible. | 
| Report bugs to <bug-gnu-gettext@gnu.org>. | 
| Copyright 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. | 
| 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. |