How to get set variable in a shell script

Question

I can succeed to grab the environment variable in command line.

But if I put the commands in a .sh file, then run the .sh file.

Nothing is printed. Any reason ?

root@mydesktop:/tmp$ s1="hello stackoverflow"
root@mydesktop:/tmp$ echo $s1
hello stackoverflow
root@mydesktop:/tmp$/tmp$ set | grep s1
s1='hello stackoverflow'

--> it's good to show as expect, then I save those commands to a script file test.sh

#!/bin/sh    
echo $s1
echo ${s1}    
hello=$( set | grep s1 )
echo $hello   
echo ${hello}

But after script run, I don't get the expected result

root@mydesktop:/tmp$ ./test.sh


root@mydesktop:/tmp$

Any idea ?

Update:

OK , found strange thing:

#set
s1=' balaba '
'
s2='another string'

the is one more ' --> it could be the root cause.

For me it works in bash (though your code, in general, would show much more than just the setting of the variable). What bash version do you have, i.e. what does echo $BASH_VERSION say? — user1934428
– user1934428, Commented Apr 27, 2017 at 7:55
If you want to export a variable, you need to export it! :) export s1="foo bar" — hek2mgl
– hek2mgl, Commented Apr 27, 2017 at 7:55
s1 is example here. It's not set by me. It's there after system boot up. — Niuya
– Niuya, Commented Apr 27, 2017 at 7:58

leftjoin · Accepted Answer · 2017-04-27 08:01:25Z

2

By default variables declared without export are not passed to subprocesses.

 export s1="hello stackoverflow"

if it was set not by you , just export it:

export s1

./test.sh

---output

hello stackoverflow
s1='hello stackoverflow'

And of course use quotes:

#!/bin/sh
echo "$s1"
hello=$( set | grep s1 )
echo "$hello

answered Apr 27, 2017 at 8:01

leftjoin

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2 Comments

Niuya Over a year ago

But in my real product environment, I still can't get the value. let me check what's the different.Will feedback later.

leftjoin Over a year ago

export should be before script run, not inside. Before running test.sh

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