Linux and Unix printenv command
printenv prints all or part of the environment.
printenv [OPTION]... [VARIABLE]...
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.
|-0, --null||end each output line with 0 byte rather than newline.|
|--help||display a help message, and exit.|
Display the location of the current user's home directory.
Display the values of all environment variables.
env — Report the value of environment variables.