docker - Passing a complex shell script via docker exec sh -c "..."

Question

I have a script that works fine in sh on a linux host as well as inside an alpine container. But when I try executing that using docker exec <containerID> sh -c "<script>" it misbehaves. The script's function is to output stuff similar to ps.

systick=$(getconf CLK_TCK); for c in /proc/*/cmdline; do d=$(dirname $c); name=$(grep Name: $d/status); pid=$(basename $d); uid=$(grep Uid: $d/status); uid=$(echo ${uid#Uid:} | xargs); uid=${uid%% *}; user=$(grep :$uid:[0-9] /etc/passwd); user=${user%%:*}; cmdline=$(cat $c|xargs -0 echo); starttime=$(($(awk '{print $22}' $d/stat) / systick)); uptime=$(awk '{print int($1)}' /proc/uptime); elapsed=$(($uptime-$starttime)); echo $pid $user $elapsed $cmdline; done

EDIT: sh -c "<script>" has the same behavior.

标签： dockershdocker-exec

Answer 1

You are not able to run this script from docker exec because the variables will be interpolated before they sent to the container (i.e., you are going to get values from your local machine, not from within the container).

In order to run it as you wish, you need to replace $ with \$ for every occurrence of $ in your script.

What might work better is to put your script into a file, then map the file to a location within the container, using -v (i.e., -v script.sh:/path/to/script.sh), and call the script via docker exec /path/to/script.sh