String variable output showing strange Single Quote in Bash

Question

I have following scripts

#!/bin/bash
set -o xtrace
gluster_volume="a.example.com:/data/brick1/gv0 b.example.com:/data/brick1/gv0"
gluster volume create gv0 replica 2 ${gluster_volume} force

While executing second line this script throwing error related to gluster_volume that its unable read complete line and just considering a.example.com:/data/brick1/gv0 b.example.com(so look like gluster command not able parse it).

Then I run this script with trace and found that command is like

gluster volume create gv0 replica 2 'a.example.com:/data/brick1/gv0 b.example.com:/data/brick1/gv0' force

so script is adding single quotes which are creating problem. I was under the impression that it's due to set -o xtrace the single quotes are not part of the value, just part of the displayed command line. But its not true. if i run above command on command prompt it gives same error and on removing quotes it works.

How i can change my script so it don't add quotes? (I tried to remove quote with sed but not working, something happening at run time).

I need gluster_volume with dynamic values.

Update1:

workers=`echo "${WORKER_HOST_IP}"|sed "s/,$//"`
IFS=','
for worker in ${workers}; do
    IFS='-' read -r -a array <<< "$worker"

    gluster_volume+=${array[0]}':/data/brick1/gv0 '

done

Have you tried looking at this? https://stackoverflow.com/questions/9733338/shell-script-remove-first-and-last-quote-from-a-variable — TinkerTenorSoftwareGuy, Aug 06 '20 at 16:11
Another option might be using the eval command... just concat the string to form the entire command, first. https://linuxhint.com/bash_eval_command/ — TinkerTenorSoftwareGuy, Aug 06 '20 at 16:13
I suspect that you are not using `bash` but `zsh`. Add this to your script and its output to your question: `echo "$BASH_VERSION"`. How do you start your script? — Cyrus, Aug 06 '20 at 16:14
@Cyrus I am calling this script from other like `sh myscript.sh` — ImranRazaKhan, Aug 06 '20 at 16:24
`sh` ([Bourne-shell](https://en.wikipedia.org/wiki/Bourne_shell)) is usally not `bash` ([Bourne-again shell](https://en.wikipedia.org/wiki/Bash_(Unix_shell))). — Cyrus, Aug 06 '20 at 16:43
@Cyrus bash doesn't helped so i will use eval it works for me thanks. — ImranRazaKhan, Aug 06 '20 at 16:49
I'd avoid `eval` if at all possible -- it has a well-deserved reputation as a bug magnet. The single-quotes are just the shell's way of indicating that that string isn't being split up into separate arguments ("words"). I'd concentrate on trying to figure out *why* it isn't being split. — Gordon Davisson, Aug 06 '20 at 16:53
@GordonDavisson Thanks for highlighting it look like gluster bug as its not able to parse, i will raise accordingly. — ImranRazaKhan, Aug 06 '20 at 18:18
@ImranRazaKhan I don't think it can be `gluster` -- the shell should perform word splitting before passing the arguments to `gluster`, so it has to be happening at the shell level. The only things I can think of that'd cause this are that you're running `zsh` as the shell, or that the `IFS` variable has been set to some unusual value. It sounds like you've eliminated `zsh`; is it possible something has messed with `IFS`? — Gordon Davisson, Aug 07 '20 at 00:56
@GordonDavisson For sake of simplicity i provided trimmed code previously, Now i shared the code which is using IFS to make gluster_volume variable, you can see updated code under update1 — ImranRazaKhan, Aug 07 '20 at 11:20
That `IFS=','` explains it. You could reset `IFS` back to normal after the loop (there are several ways to do this, none perfect), but I'd look at using a better method to split `workers`. The best way to do that depends on the exact format of the `WORKER_HOST_IP` variable. — Gordon Davisson, Aug 07 '20 at 19:49

score 1 · Answer 1 · answered Sep 16 '20 at 10:35

You can try eval(Be careful if the list of bricks or the string comes from an external untrusted source)

#!/bin/bash
set -o xtrace
gluster_volume="a.example.com:/data/brick1/gv0 b.example.com:/data/brick1/gv0"
eval "gluster volume create gv0 replica 2 ${gluster_volume} force"

String variable output showing strange Single Quote in Bash

1 Answers1