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Reading about this question: In zsh how can I list all the environment variables?, I wondered, how can I list all the shell variables?

Also, does the distinction between shell variables and environment variables apply to shells other than zsh?

I am primarily interested in Bash and Zsh, but it would be great to know how to do this in other mainstream shells.

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  • A general warning related to most methods: When using such things in scripts, beware variables whose value contains a newline, e.g. IFS. Their representation in the output may span multiple lines.
    – Palec
    May 24, 2023 at 17:48

4 Answers 4

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List all shell variables

bash : use set -o posix ; set. The posix option avoids outputting too much information, like function definitions. declare -p also works.

zsh : use typeset.

Shell variables and environment variables

An environment variable is available to exec()-ed child processes (as a copy; if parent process change the variable, the child environment is not updated). A non-environment variable is only available to the current running shell and fork()-ed subshells. This distinction is present in all shells.

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  • 1
    The question also has an answer here : stackoverflow.com/questions/1305237/…
    – Uriel
    Dec 26, 2014 at 14:05
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    set -o posix doesn't exist in zsh; set doesn't output function definitions.
    – vinc17
    Dec 26, 2014 at 14:33
  • 1
    set -o posix is a syntax error in most shells.
    – mikeserv
    Dec 26, 2014 at 18:29
  • 3
    Shell variables are also available in child processes. The difference comes when the child process executes a new program: environment variables are passed along in exec, shell variables are not.
    – Barmar
    Dec 31, 2014 at 19:03
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    In bash: declare -px or simply declare -x will print only exported variables.
    – user232326
    Nov 21, 2018 at 3:59
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There are many alternatives:

printenv

Print the values of the specified environment VARIABLE(s). If no VARIABLE is specified, print name and value pairs for them all.

env

env - run a program in a modified environment

export

Set an environment variable. Mark each name to be passed to child processes in the environment.....

-p Display output in a form that may be reused as input.

If no names are supplied, or if the `-p' option is given, a list of exported names is displayed.

set

is useful to get shell variables as well.

If you need extra info (integer, exported) you should instead use

typeset

export has an advantage, that its output can be immediately read back onto the shell.

Lastly, there is

compgen -v

Display possible completions depending on the options.

which shows all variables, shell and environment, without their value or extra info. You will have to echo $VARIABLE_NAME to find the variable value. But at least the list is complete. It belongs to bash, not zsh.

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    export has no advantage over set, at least, when it comes to quoting for shell re-entry. And printenv and env are not at all about shell variables, though these do often coincide with environment variables.
    – mikeserv
    Dec 26, 2014 at 17:05
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    compgen -e displays only exported shell variables. Details and other options in this answer.
    – Ethan
    Jan 29, 2023 at 6:06
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With zsh, you can use typeset, which gives more information than set, e.g. the type of the variables. You can still filter the output with grep or sed, depending on what you want. Environment variables are marked as exported in the output.

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I had just needed listing only the variables, not their values. For this, I used

env | awk -F '=' '{ print $1 }'

To have all of them in a single line

env | awk -F '=' '{ print $1 }' | tr '\n' ' '
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  • OP was asking about the "shell variables" rather than the environment variables. Your info about how to only show the variable names is a useful addition to the discussion. set -o posix ; set | awk -F '=' '{ print $1 }' would be just the shell variable names. Thanks! Jun 27, 2020 at 4:45

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