What is the export command supposed to do in Linux?

Question

score 9 · Answer 1 · answered Mar 19 '10 at 20:47

9

Export a shell variable as environment variable.

answered Mar 19 '10 at 20:47

Peter Eisentraut

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1
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The net result is that when you 'export' a variable, it becomes available as an environment variable within any applications you run within that shell. – McJeff Mar 19 '10 at 20:52
Can you show an example usage? – benstpierre Mar 19 '10 at 20:55
1

Have you tried the `man` page? http://ss64.com/bash/export.html – ceejayoz Mar 19 '10 at 20:58

score 8 · Accepted Answer · edited Nov 07 '18 at 10:30

Here is an example to demonstrate the behavior.

$ # set testvar to be a value
$ testvar=asdf
$ # demonstrate that it is set in the current shell
$ echo $testvar
$ # create a bash subprocess and examine the environment.
$ bash -c "export | grep 'testvar'"

$ bash -c 'echo $testvar'

$ # export testvar and set it to the a value of foo
$ export testvar=foo
$ # create a bash subprocess and examine the environment.
$ bash -c "export | grep 'testvar'"
declare -x testvar="foo"
$ bash -c 'echo $testvar'
foo
$ # mark testvar to not be exported
$ export -n testvar
$ bash -c "export | grep 'testvar'"

$ bash -c 'echo $testvar'

You will notice that without export the new bash process you created was not able to see testvar. When testvar was exported, the new process was able to see testvar.

score 2 · Answer 3 · answered Mar 19 '10 at 21:19

2

Please see this Bash by example tutorial from IBM. It even includes an example of using export.

answered Mar 19 '10 at 21:19

mctylr

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I know it's generally against SE policy to recommend an external link (they have a habit of dying), however the page is far too large and detailed to pull into an answer. I gave a +1 because Bash by Example is an *excellent* resource. And far better than `man`. – Django Reinhardt Feb 16 '21 at 17:36

What is the export command supposed to do in Linux?

3 Answers3