Posix shell script - Save multi line command output to variable

Question

When I save a command output which contains several lines to a variable directly into my terminal, I have the following results :

$ dirs=$(ls -1d /mnt/*/)
$ echo $dirs
/mnt/ext4/ /mnt/local/ /mnt/remote/ /mnt/test/
$ echo "$dirs"
/mnt/ext4/
/mnt/local/
/mnt/remote/
/mnt/test/

However when using it from a posix shell script the result is different. Here is the script

#!/bin/sh

dirs=$(ls -1d $1)
echo "inline"
echo $dirs
echo "multiline"
echo "$dirs"

And here is the script output

$ ./test.sh /mnt/*/
inline
/mnt/ext4/
multiline
/mnt/ext4/

This happens even if I use bash instead of sh.

Does anyone know how I could save the output of ls -1d /mnt/*/ into a variable keeping the full output ?
I would like to parse each of the four directory paths inside a for loop.

Answer 1

$ ./test.sh /mnt/*/

The glob here expands to the directory names as separate arguments, same as if you wrote them out manually on the command line:

$ ./test.sh /mnt/ext4/ /mnt/local/ /mnt/remote/ /mnt/test/

However, in the script itself, you refer to only the first argument, $1:

dirs=$(ls -1d $1)

If you want to refer to all the arguments, use "$@" (with the quotes).

However, all you're doing with the directory names here is to run ls on them, which just prints the same names out (though on separate lines). So, if you just want the list of the arguments as a string, you don't need to run the ls command at all, just assign dirs="$@".

Nevertheless, in most, if not all cases it's better to just keep the list of file names in the positional parameters, and loop over them with

for f in "$@"; do ...

or

for f
do ...

Note that file names might contain white space, and when you concatenate the names to a single string, you lose the meaning of the whitespace within the names. foo bar doo might be three files, or the two files foo bar and doo.