Question

a shell script:

VAR=(aa bb cc)

for i in "${VAR[@]}"
do
        echo $i;
done

when run it using . ar_test.sh, it works.

zhangyf@zhangyf-desktop:~/test$ . ar_test.sh 
aa
bb
cc

but fails in this way,

zhangyf@zhangyf-desktop:~/test$ ./ar_test.sh 
./ar_test.sh: 9: Syntax error: "(" unexpected

There are other lines in the file, so line 9 is actually VAR=(aa bb cc). I know the difference is that the latter forks a new shell process while the former ones run the script in the current shell, but why does the result differs so much?

Answer 1

The difference is not a fork, but different shells. . sources file in the current shell and ./ar_test.sh runs executable with default shell (/bin/sh), which may not support arrays. Use shebang as the first line of your script to specify proper shell:

#!/bin/bash
...other code goes here...