envsubst
substitutes environment variables in shell format strings
TLDR
Replace environment variables in stdin and output to stdout
Replace environment variables in an input file and output to stdout
Replace environment variables in an input file and output to a file
Replace environment variables in an input file from a space-separated list
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-FORMAT, one per line.
REPORTING BUGS
Report bugs in the bug tracker at <https://savannah.gnu.org/projects/gettext> or by email to <bug-gettext@gnu.org>.
COPYRIGHT
Copyright © 2003-2023 Free Software Foundation, Inc. License GPLv3+:
GNU GPL version 3 or later
<https://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.
AUTHOR
Written by Bruno Haible.