Memo on manipulating Linux environment variables

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Some common environment variables

• PATH : list of paths to be searched for commands.
• USER : current logged in user.
• HOME : current user’s home directory.
• BASH_VERSION : bash version
• SHELL : current user’s shell path.
• EDITOR : default file editor used when we type edit in the terminal.
• LOGNAME : name of the current user.
• LANG : current locales settings.
• TERM : current terminal emulation.
• MAIL : current user’s email storing location.

Display environment variable values

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# display the USER env var
printenv USER

# display both HOME SHELL env vars
printenv HOME SHELL

# display using echo
echo $PATH

# list all env vars
printenv

# list all: environment, shell and variables, and shell functions
set | less

Set environment variables for a shell session

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# set FOO_VAR and BAR_VAR in the current shell session only
export FOO_VAR='foo'
export BAR_VAR='var'

Set environment variables permanently

You can edit one these files:

• ~/.bashrc : per-user environment variables loaded by the bash shell. Use source ~/.bashrc to load the new vars in the current shell.

  1 2	export USER_VAR1="foo" export USER_VAR2="bar"

• /etc/profile : environment variables loaded by the bash shell for all users.

  1 2	export SHELL_VAR1="foo" export SHELL_VAR2="bar"

• /etc/environment : system-wide environment variables. ⚠️ In this file, we don’t write export.

  1 2	ENV_VAR1="foo" ENV_VAR2="bar"

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Written on Tue Dec 13th 2022, 10:02 GMT+00:00.
Last updated on Tue Dec 13th 2022, 10:02 GMT+00:00.