printenv --version (return code: 0)
printenv (GNU coreutils) 8.25
Copyright (C) 2016 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.
Written by David MacKenzie and Richard Mlynarik.
printenv --help (return code: 0)
Usage: printenv [OPTION]... [VARIABLE]...
Print the values of the specified environment VARIABLE(s).
If no VARIABLE is specified, print name and value pairs for them all.
-0, --null end each output line with NUL, not newline
--help display this help and exit
--version output version information and exit
NOTE: your shell may have its own version of printenv, which usually supersedes
the version described here. Please refer to your shell's documentation
for details about the options it supports.
GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
Full documentation at: <http://www.gnu.org/software/coreutils/printenv>
or available locally via: info '(coreutils) printenv invocation'