Linux get all env variables

How do I see a list of all currently defined environment variables in a Linux bash terminal?

In a Linux bash terminal, there are often many environment variables that have been set, like $PATH and $HOME . Is it possible to see all of the environment variables that have been set? How?

5 Answers 5

TL;DR: use (set -o posix ; set)

According to the Bash manual you can use the set built-in command to show all of the environment variables that have been set. The set command will also display the definitions of any functions. If you only want to see the variables, and not the functions, then you can turn on POSIX mode before running the set command. The easiest way to do that is with set -o posix , but that will leave POSIX mode on until you turn it off with set +o posix .

Therefore, the following command will show all of the defined environment variables by using a subshell without affecting POSIX compliance in your current shell.

@RedGrittyBrick and @iglvzx suggested using the env command, however this command will not provide a complete listing of environment variables. env will only show the varaibles that have been marked for export. Compare the output of env | sort and export -p and you will see what I mean. You can run comm -23 <(set -o posix; set) <(env|sort) if you want to see which environment variables are not being exported.

The reason for the discrepancy is that env is a separate executable as opposed to set which is a shell built-in command. According to the Bash manual, when a command is executed that is not a shell built-in command or function it will only receive environment variables that have been marked for export in Bash. There are many variables that are not exported. Therefore, if you wish to see all of the variables that your shell has defined, you must use the set command as stated in the manual.

You can easily test this behavior for yourself using the following commands.

MY_TEST_VARIABLE="This is my test variable." set | grep MY_TEST_VARIABLE env | grep MY_TEST_VARIABLE 

You will see that set provides output while env does not.

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How to list all Linux environment variables including LD_LIBRARY_PATH

How to list all the environment variables in Linux? When I type the command env or printenv it gives me lots of variables, but some variables like LD_LIBRARY_PATH and PKG_CONFIG don’t show up in this list. I want to type a command that list all the environment variables including this variables ( LD_LIBRARY_PATH and PKG_CONFIG )

3 Answers 3

env does list all environment variables.

If LD_LIBRARY_PATH is not there, then that variable was not declared; or was declared but not export ed, so that child processes do not inherit it.

If you are setting LD_LIBRARY_PATH in your shell start-up files, like .bash_profile or .bashrc make sure it is exported:

export LD_LIBRARY_PATH=/usr/local/lib:$

This will modify the variable.

To print it, type: echo $LD_LIBRARY_PATH and it should show the above value.

If you’re seeing nothing when you print that, then the variable might not be set.

The question in fact is a good question. when run env or printenv , the output will be the system environment, but LD_LIBRARY_PATH is not belong to.

For example, if you set a=1 , you can’t show it by env . Same as LD_LIBRARY_PATH, it is used by ld.so only(ld. so – this little program that starts all your applications)

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How to Print Environment Variables in Linux

Wondering what environment variables are set on your current shell? Learn how to print environment variables in Linux.

Environment variables are specific to certain environments. A generic answer, right?

But really, those are the variables that are just specific to your current system environment such as the currently logged-in user will be stored inside the «USER» variable.

Still confused? no worries. I will walk you through a brief understanding of environment variables and then jump to various ways to print them.

What are Environment Variables?

Nope, it’s not related to your Desktop Environment.

One of the most basic environment variables that you encounter on a daily basis is Hostname. So have you ever wondered why it’s always written in all caps?

Because most of the environment variables are pre-defined by the system and are global variables so you’ll encounter them often written in all caps.

So why use environment variables in the first place?

Suppose you are a programmer and your code needs to have access to your database key which should never be shared in public.

So what options do you have while sharing the entire code on Git? Wrap the database key to the environment variable.

This way you can set instructions on Git as «if you want to make this code work, interchange this variable with your database key.»

Of course, this was the one way of using environment variables. So let’s have a look at some common environment variables in Linux.

Environment Variable	Description
HOME	Shows home directory for the current user
HOSTNAME	Contains Hostname of your system
UID	Stores unique ID of the user
SHELL	Shows the path to the shell which is being used currently
BASH_VERSION	Contains version currently used bash instance
HISTFILE	Path of the file where the history of commands is saved
TERM	Shows the type of log-in terminal you’re using
PATH	Shows path of commands and directories are separated by columns

Print Environment Variables in Linux

There are various ways through which you can print environment variables in Linux and I’ll try to cover each of them. So let’s start with the easiest one.

Using printenev Command

The printenv utility is used to print environment variables for the current shell.

Suppose I want to print the value of USERNAME using printenv so my command will be as follows:

Similarly, you can also use the printenv utility to print more than one environment variable by separating them with .

So how about printing the value of HOME and USERNAME at once using printenv?

First, it’ll print the home directory of the currently logged-in user and in the second line, the hostname will be there.

But what if you are looking for a way by which you can print each environment variable available in the current shell?

You can easily accomplish this by executing the printenv command without any options or arguments whatsoever.

Using echo Command

If you’ve been using Linux for a while, the chances of using this method to print environment variables are quite high (even if you were unaware that it’s not an environment variable).

Now, let me show you how you’re supposed to print the value of USERNAME with echo:

But what if you want to print multiple environment variables using echo? just follow the given syntax:

So how about printing values of HOME, USERNAME, and HOSTNAME all at once using echo?

echo -e "$USERNAME \n$HOME \n$HOSTNAME"

Using env Command

The env command is generally used by shell scripts to launch the correct interpreter but you can also use the env command to list available environment variables.

The env command if applied without any arguments and options, will print all the available environment variables.

But what if you want to get the value of a specific environment variable? you can easily filter results with the grep command.

For demonstration, I’ll be printing out the value of HOME with the echo command:

Using declare Command

The declare command is used to declare and print the value of variables in the shell.

Like any other example shown above, you can use declare without any argument and will bring the list of available variables.

Previously, I showed you how you can use the grep command to filter results but what if you want to filter more than one result?

First, let’s have a look at the syntax for filtering multiple environment variables:

For example, let’s print the value of HOSTNAME and USERNAME:

declare | grep 'HOSTNAME\|USERNAME'

Using set Command

Generally, the set command is used to set and unset flags in the shell so that you determine the exact behavior for the upcoming process.

But you can also use the set command to print environment variables for the current shell.

To print each environment variable, use the given command:

You can use the same approach used in the above method to filter results from the set command.

But still, let’s look at a simple example using the grep command to print multiple environment variables.

set | grep 'HISTFILESIZE\|HISTFILE\|GNOME_SHELL_SESSION_MODE'

Wrapping up

Though there are various methods for printing environment variables, I’d highly suggest you use the first method the syntax is the least complicated in terms of filtering specific variables.

And if you are still confused, the comments section is open to you.

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What are my environment variables? [closed]

Wow that was fast! I guess all the command do the trick. The export command gave me a lot of «declare -x» in front. Thanks guys!

It was inappropriate to close this question as off topic. When programming on Linux, as I am doing at the moment, it is often useful to discover what the environmental variables are. Quite a lot of people have found this to be a useful question, including me.

4 Answers 4

I am not sure if thats what you want, but try printenv
This will show you all your environment variables.

Just execute env in a terminal.

$ env TERM=xterm SHELL=/bin/bash USER=joksnet USERNAME=joksnet DESKTOP_SESSION=gnome PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games PWD=/home/joksnet GDM_KEYBOARD_LAYOUT=us LANG=en_US.utf8 HOME=/home/joksnet DISPLAY=:0.0 COLORTERM=gnome-terminal _=/usr/bin/env 

Type export without any parameters.

SET(P) POSIX Programmer’s Manual SET(P) NAME set - set or unset options and positional parameters SYNOPSIS set [-abCefmnuvx][-h][-o option][argument. ] set [+abCefmnuvx][+h][+o option][argument. ] set -- [argument. ] set -o set +o DESCRIPTION If no options or arguments are specified, set shall write the names and values of all shell variables in the collation sequence of the current locale. Each name shall start on a separate line, using the format: "%s=%s\n", , The value string shall be written with appropriate quoting; see the description of shell quoting in Quoting . The output shall be suitable for reinput to the shell, setting or resetting, as far as possible, the variables that are currently set; read-only variables cannot be reset. 

env or printenv are better. In bash, set will also print all your defined functions, which on a system like ubuntu, is a very long printout.

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