Bash array access not working as expected

Question

I am re-writing code to work with a newer system. I did not write the original code, but I'm trying to use the old code as a template. When I run the command by itself, it works fine. When I try running it as part of a script or function in the shell, it does not.

#!/bin/bash
function find_user() {
    local txt
    local user_list
    local username
    local displayName

    echo "Find User"
    echo "---------"

    echo -n "Enter search text (e.g: lib): "
    read txt

    if [ -z "$txt" ] || ! validate_fullname "$txt"; then
        echo "Search cancelled."
    else
        echo
        user_list="$(samba-tool user list | grep -i ${txt} | sort)"
        (
            echo "Username Full_Name"
            echo "-------- ---------"
            # Dev Note: Get the username, then displayName parameter, replacing
            # the spaces in displayName with an underscore. Do not need to look
            # for a dollar sign anymore, as computers are not listed as "user"
            # class objects in AD.
            for a in "${user_list[@]}"; do
                username=$a
                displayName="$(
                    samba-tool user show ${a} | grep 'displayName:' | \
                        awk -F: '{gsub(/^[ \t]+/,"""",$2); gsub(/ ./,""_"",$3); print $2}' | \
                        tr ' ' '_')"
                echo "${username} ${displayName}"
            done
        )| column -t
     fi
}

When I try to run it, and enter the find_user function, it prompts for the search text (i.e. I can type js) and press Enter.

My issue is with the $displayName= part. It seems to generate an empty string when running in the script. If I run the command manually from the terminal (filling in, for example, jsmith as a substitute for ${a}), it outputs the full name correctly.

My system is running bash.

What is going on, and how can I fix this?

Answer 1

The problem is that user_list is accessed as an array

for a in "${user_list[@]}"

but set as a string:

user_list="$(samba-tool user list | grep -i ${txt} | sort)"

Instead you need

IFS=$'\n'     # split on newline characters
set -o noglob # disable globbing

# assign the users to the array using the split+glob operator
# (implicitly invoked in bash when you leave a command substitution
# unquoted in list context):
user_list=( $(samba-tool user list | grep -ie "${txt}" | sort) )

Or better (though bash-specific):

readarray -t user_list < <(samba-tool user list)

(note that that one would create one empty element for each empty line of the input if any, contrary to the split+glob approach which would discard empty lines).