When we export a local variable declared within a current shell does it get passed to future sub shells,processes , child processes or future child processes? I was told it get passed to future sub shells. Is it correct?
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2 Answers
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Just try?
$ export foo=bar
$ bash
$ echo $foo
bar
$ bash
$ echo $foo
bar
$ exit
$ exit
$
tl;dr: Yes.
Amadan
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1
This simple test will answer you by itself:
$ VAR1="Hello, World!"
$ echo "${VAR1}"
Hello, World!
$ bash
$ echo "${VAR1}"
$ export VAR1="Hello, World!"
$ echo "${VAR1}"
Hello, World!
$ bash
$ echo "${VAR1}"
Hello, World!
$
Breaking it down:
No export ...
$ VAR1="Hello, World!"
$ echo "${VAR1}"
Hello, World!
$ bash
$ echo "${VAR1}"
$
... leads to VAR1 not being defined in the child.
While with export ...
$ export VAR1="Hello, World!"
$ echo "${VAR1}"
Hello, World!
$ bash
$ echo "${VAR1}"
Hello, World!
$
... leads to VAR1 being defined in the child.
pah
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so VAR1 can get passed into child ? – Char Aug 10 '16 at 03:02
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1It **is** *passed* to the child environment, yes. – pah Aug 10 '16 at 03:02
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but it will not be passed to child processes right? – Char Aug 10 '16 at 03:03
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1When `bash` is called after the export, it is a child process of the parent shell. – pah Aug 10 '16 at 03:04