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-FORMAT, one per line.

AUTHOR

       Written by Bruno Haible.

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 © 2003-2020 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.