bash forgets export variable

Question

I am unable to make even the simplest export of variables, from within scripts, to work in my bash - what am I dooing wrong?

File test.sh :

#!/bin/bash
echo $ttt
ttt="fffalse"
export ttt
echo $ttt

bash test :

hpek@hpek:~/temp$ export ttt="tttrue"
hpek@hpek:~/temp$ ./test.sh 
tttrue
fffalse
hpek@hpek:~/temp$ ./test.sh 
tttrue
fffalse
hpek@hpek:~/temp$

Edit:

I now know from the answers, that this will not work. -but how can make a single variable remembered between processes? Do I need to store it in a file?

+1 for the title. Bad bash! :)))

yazu
– yazu

2012-05-05 01:11:19 +00:00
Commented May 5, 2012 at 1:11 — yazu
– yazu, Commented May 5, 2012 at 1:11

kev · Accepted Answer · 2012-05-05 00:36:13Z

4

./test.sh is the same as bash test.sh

Each shell script running is, in effect, a subprocess (child process) of the parent shell.
And subprocess cannot export env-var to it's parent.

You can try this（run in the same environment）:

. test.sh

edited May 5, 2012 at 0:36

answered May 5, 2012 at 0:28

kev

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2 Comments

hpekristiansen Over a year ago

". test.sh" is actually working - thanks. What does this mean? that is is run in current shell and not as a child?

mgilson Over a year ago

@Hans-PeterE.Kristiansen . test.sh is completely equivalent to source test.sh which just means that the interpreter takes each line from test.sh and runs it in the current environment as if you had typed it into the current script. If you're familiar with C, it's somewhat similar to what the preprocessor does when you do #include "file.h". see this link: ( ss64.com/bash/period.html )

geekosaur · Accepted Answer · 2012-05-05 00:28:21Z

3

export works in the current process and any children spawned afterward; it does not work across process boundaries (parents, existing children, unrelated processes). The environment behaves like a sort of shadow argument list, not like a filesystem or mailbox.

answered May 5, 2012 at 0:28

geekosaur

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