bash array acting weird

Question

I have two folders under /tmp.

From terminal:

ls -d /tmp/firefox-* /tmp/firefox-sy2vakcj.default-esr-charlie-cache /tmp/firefox-sy2vakcj.default-esr-charlie-profile 

or

compgen -G /tmp/firefox-* /tmp/firefox-sy2vakcj.default-esr-charlie-cache /tmp/firefox-sy2vakcj.default-esr-charlie-profile 

And i can store the output in an array as well:

arr=( $(ls -d /tmp/firefox-*) ) echo $arr tmp/firefox-sy2vakcj.default-esr-charlie-cache /tmp/firefox-sy2vakcj.default-esr-charlie-profile echo $arr[1] tmp/firefox-sy2vakcj.default-esr-charlie-cache echo $arr[2] /tmp/firefox-sy2vakcj.default-esr-charlie-profile 

so far so good.

But if i attempt the same thing from a script:

 ... ... arr=( "$(ls -d /tmp/firefox-*)" ) ||( echo "directory doesn't exist" && exit 1) #arr=( "$(compgen -G /tmp/firefox-*)" ) ||( echo "directory doesn't exist" && exit 1) echo "this is a test for arr[1]: $arr[1]" echo "this is a test for arr[2]: $arr[2]" ... 

I get the output:

From script:

for ls -d this is the output:

+ arr=("$(ls -d /tmp/firefox-*)") ++ ls -d '/tmp/firefox-*' ls: cannot access '/tmp/firefox-*': No such file or directory + echo 'directory doesn'\''t exist' directory doesn't exist 

and for compgen -G , this is the output:

this is a test for arr[1]: /tmp/firefox-sy2vakcj.default-esr-charlie-cache /tmp/firefox-sy2vakcj.default-esr-charlie-profile[1] this is a test for arr[2]: /tmp/firefox-sy2vakcj.default-esr-charlie-cache /tmp/firefox-sy2vakcj.default-esr-charlie-profile[2] 

My questions:

1. Why is the glob not expanding in the subshell for the command ls -d ?

2. With compgen -G, how are the values being stored in the array? the output seems like each entry in the array is storing both the directory entry with the second one with its own index array?

3. Is the output from terminal for both commands different from the script, or am i missing something?

Answer 1

1. Why is the glob not expanding in the subshell for the command ls -d ?

You've probably turned off globbing by using set -f. To demonstrate:

$ touch firefox-1 firefox-2 $ arr=( firefox-* ); declare -p arr declare -a arr=([0]="firefox-1" [1]="firefox-2") $ set -f $ arr=( firefox-* ); declare -p arr declare -a arr=([0]="firefox-*") 

2. With compgen -G, how are the values being stored in the array? the output seems like each entry in the array is storing both the directory entry with the second one with its own index array?

When you do arr=( "$(compgen -G /tmp/firefox-*)" ), the double quotes force the compgen output to be stored as a single element in the array. In this case, to read the lines of output into an array, use mapfile with a process substitution:

$ mapfile -t arr < <(compgen -G ./firefox-*) $ declare -p arr declare -a arr=([0]="./firefox-1" [1]="./firefox-2") 

3. Is the output from terminal for both commands different from the script, or am i missing something?

Looks like your interactive shell is zsh. Aside from that, you're missing the parameter expansion syntax for array elements requiring the braces (3.5.3 Shell Parameter Expansion), and that bash arrays are indexed starting from zero:

echo "${arr[0]}"