Piping bash commands in kubectl exec

kubectl-exec-pipe-commands.md

Bash commands connected using pipe(|) are not executed correctly in kubectl exec.

Example:

kubectl exec -ti <POD> -- pg_dump -h localhost -t my_table | psql -d <TARGET_DB> -h localhost

Here I want to run the pg_dump command first and redirect the output to the psql command as input using pipe(|). But kubectl takes commands only until pipe character, pg_dump in my case and psql has been run on host machine instead of inside the <POD>. The solution is to wrap all commands using double quote(") and run these commands using bash -c.

Fixed example:

kubectl exec -ti <POD> -- bash -c "pg_dump -h localhost -t my_table | psql -d <TARGET_DB> -h localhost"

This is not an issue with kubectl. It is how the shell works: it first opens the left side of the pipe

kubectl exec -ti <POD> -- pg_dump -h localhost -t my_table

to produce the input to the right side of the pipe

psql -d <TARGET_DB> -h localhost

You need bash -c because you want the pipe to run completely inside the pod.