Capture output of bash script over ssh within script

Question

I am aware of this discussion: Running A Bash Script Over SSH

However, I have a somewhat varied take on it - and it's got me stumped.

I have an ssh alias in my ~/.ssh/config called remServer to which I can ssh just fine. I'd like to run some remote commands on that server and deal with the output on the local server.

My problem comes to substituting variables into the ssh commands (such an elementary subject) but I'm missing something here.

Here's the issue:

#this works
op="ls"
cmd="ssh remServer '$op'"
res=`$cmd`
echo $res

#this doesn't
op="ls -lt"
cmd="ssh remServer '$op'"
res=`$cmd`
echo $res

No matter how many ways I use single or double quotes, I only get back something along the lines of:

bash ls -lt command not found

What happens when you run ssh remServer 'ls' interactively? Could you check in the shell configuration files (.bashrc and so on) on the remote system to see if there is an alias for the ls command? — Kenster
– Kenster, Commented Mar 1, 2018 at 16:36
Hello! Thanks for your viewing. Running interactively, I get a simple listing of files (as expected) - just as I do when on the remote server itself (so nothing changing the ls command there). — Kid Codester
– Kid Codester, Commented Mar 1, 2018 at 16:58

that other guy · Accepted Answer · 2018-03-01 17:08:16Z

2

Since you pass in literal single quotes, the command executed becomes 'ls -lt' which gives the same error locally too (as opposed to ls -lt without quotes).

The easiest solution is just removing the quotes:

op="ls -lt"
cmd="ssh remServer $op"
res=`$cmd`
echo $res

The better solution is using proper arrays and escaping:

op=(ls -lt)
cmd=(ssh remServer "$(printf '%q ' "${op[@]}")" )
res=$("${cmd[@]}")
echo "$res"

answered Mar 1, 2018 at 17:08

that other guy

125k12 gold badges187 silver badges214 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Capture output of bash script over ssh within script

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related