Bash script to get into a running container and then run another bash script from that container

Question

I have a shell script which runs as follows :

image_id=$(docker ps -a | grep postgres | awk -F' ' '{print $1}')
full_id=$(docker ps -a --no-trunc -q | grep $image_id)
docker exec -i -t $full_id bash

When I run this from the base linux OS, I expect to actually enter the postgres container which is a running container. But the issue is that the shell script hangs on 3rd line during ' docker exec' step.

My end goal is using the bash script, enter a running postgres container and run another bash script inside that container. However the same command when I run it from command line, it works fine and gets me into the postgres container.

Please help, I have spent hours and hours to solve this but no progress.

Thanks again

What's the final command you want to run in the container?

Matt
– Matt

2015-11-27 01:54:33 +00:00
Commented Nov 27, 2015 at 1:54 — Matt
– Matt, Commented Nov 27, 2015 at 1:54

Matt · Accepted Answer · 2015-11-27 02:07:35Z

2

Your setup is a bit more complex than it needs to be.

Docker ps can filter containers directly with the --filter= option

docker ps --no-trunc --quiet --filter="ancestor=postgres"

You can also --name containers when you run them which will be less fraught with danger than the script you are attempting

docker run --detach --name postgres_whatever postgres
docker exec -ti postgres_whatever bash

I'm not sure that your script is hanging as opposed to sitting there waiting for input. Try running a command directly

Using naming

exec_test.sh

#!/usr/bin/env bash
docker exec postgres_whatever echo "I have run the test"

When run

$ ./exec_test.sh
I have run the test

Without naming

exec_filter_test.sh

#!/usr/bin/env bash
id=$(docker ps --no-trunc --quiet --filter="ancestor=postgres")
[ -z "$id" ] && echo "no id" && exit 1
docker exec "${id}" echo "I have run the test"

When run

$ ./exec_filter_test.sh 
I have run the test

answered Nov 27, 2015 at 2:07

Matt

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1 Comment

skyrocker Over a year ago

Thanks Matt. That really helped .

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