How to list all variables names and their current values?

For bash: (the standard shell in Ubuntu)

Enter the following command in a terminal to print all the environment variables:

printenv

For further information about this command, read the printenv man page.

To show a list including the "shell variables" you can enter the next command:

( set -o posix ; set ) | less

This will show you not only the shell variables, but the environment variables too.

For more information related with this topic read:

• How to list variables declared in script in bash? from SO and
• How to print all environment variables defined (but not necessarily exported) in bash from UnixSE
• Environment variable vs Shell variable, what's the difference?

For zsh: (an advanced shell)

Use the following command:

( setopt posixbuiltin; set; ) | less

For more information about ZSH options, see zshoptions man page.

You can see all variables with the declare builtin.

declare -p

If you're only interested in environment variables, use

declare -xp

Run help declare to see what the other options are.

I know that this question is quite old and answered, but I think I can add a bit of useful information.

In all the methods described above, the procedure that is suggested is:

• launch a terminal
• show the environment variables using env, or printenv or whatever

The problem of these solutions are that you are seeing the environment variables of the shell that is running into the terminal. You are not seeing the environment variables available to an application run, for example, directly by the graphic interface.

This is noticeable if, for example, you use your ~/.profile, or .bashrc, or .zshenv (depending on your shell) to modify the environment variables --- like the classic addition of directories to the path.

To see the environment variables available to the application started directly in the graphic environment, you can do the following (in Gnome Shell, I am sure there is an equivalent method in all the other DE):

• press Alt-F2
• run the command xterm -e bash --noprofile --norc

(Or, if you do not have xterm, gnome-terminal -- bash --noprofile --norc --- thanks to @Mike Nakis for the comment).

You now have a terminal with a shell that did not add any environment variables. You can use env here to list all your environment variables:

Obviously the new shell will have the environment variables added by the system files, but that variables should be available (by inheritance) to all programs in the system anyway.

I am posting this because it's the fourth time I have to search this trick again, checking my .pam_environment file. So now I will find it faster (and in the process, I hope helping someone else...)

To list the environment variables in terminal with CTRL+ALT+T you can use env command.

for example :

[raja@localhost ~]$ env
XDG_VTNR=1
SSH_AGENT_PID=3671
XDG_SESSION_ID=3
HOSTNAME=localhost.localdomain
IMSETTINGS_INTEGRATE_DESKTOP=yes
GPG_AGENT_INFO=/home/raja/.gnupg/S.gpg-agent:3691:1
GLADE_PIXMAP_PATH=:
TERM=xterm-256color
SHELL=/bin/bash
XDG_MENU_PREFIX=xfce-
DESKTOP_STARTUP_ID=
HISTSIZE=1000
XDG_SESSION_COOKIE=0250277dd805498381e96c05d88068b0-1364679772.845276-1676152201
WINDOWID=65011716
GNOME_KEYRING_CONTROL=/home/raja/.cache/keyring-N3QoQ2
IMSETTINGS_MODULE=none
QT_GRAPHICSSYSTEM_CHECKED=1
USER=raja

etc.

hope that helps.

In bash using compgen:

compgen -v | while read line; do echo $line=${!line};done  

If you want a specific environment variable, rather than printing them all with printenv, you can for example print it by doing echo "$PWD"

Most solutions here either print only environment variables, or have the drawback that env or (set -o posix; set) do not print values in easily parseable form (try to print variable A=$'a\r\nb', it has multiple lines...).

Here is a function that will print all variables, one variable per line, in the POSIX escaped form (works properly for simple text variables, does not work for arrays):

function dump_vars {
    local VARNAME
    compgen -v | while read -r VARNAME; do
        printf "$VARNAME=%q\n" "${!VARNAME}"
    done
}

Thanks to @tmgoblin for pointing out the use of compgen -v.

env is a POSIX 7 way:

export asdf=qwer
env | grep asdf

Sample output:

asdf=qwer

It only shows exported variables: non-exported variables are not usually considered "environment variables".

Prefer that over printenv, which is not POSIX. Both seem to do the same thing without arguments: https://unix.stackexchange.com/questions/123473/what-is-the-difference-between-env-and-printenv

printenv only lists exported variables, command+alt+$ ( "\e$": complete-variable ) will list all variables.

• printenv will show all the global environoment variables
• env, global environment variable after login modification
• set, will display all local environment variable, relative to the session (usually the local var is the global + the particular of the session)