how to pass output of a command to another in shell script

Question

I am trying to ssh into server, and into a docker container to run the service. however I am not able to store containerId into a variable to pass it to enter the container.

#!/bin/bash

ssh test_server << EOF
 ls 
 sudo docker ps | grep 'tests_service_image' | colrm 13                 # This command works
 containerId=$(sudo docker ps | grep 'tests_service_image' | colrm 13)  # This doesn't
 sudo docker exec -i "$containerId" bash                           # Throws error since containerId is empty
 ./run.sh 
EOF

exit

C. Keylan · Accepted Answer · 2021-01-03 15:38:10Z

1

The problem is that you are doing variable/function expansions on your own side. You need to escape those so that those expansions happen on the server side.

#!/bin/sh

ssh test_server << EOF
 containerId=\$(sudo docker ps | grep 'tests_service_image' | colrm 13)
 sudo docker exec -i "\$containerId" bash
 ./run.sh 
EOF

exit

answered Jan 3, 2021 at 15:38

C. Keylan

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Comments

Sandeep · Accepted Answer · 2020-12-24 11:17:09Z

0

Edit: Pass it directly to docker exec command like so

sudo docker exec -i $(sudo docker ps | grep 'tests_service_image' | colrm 13) bash

Original Answer:

This is written assuming that the script execution is done post sshing into the server. but modified the answer to above based on the specific query

container ID is stored in variable containerId, you are getting the error Error: No such container: because you are passing a different variable $container instead of $containerId to docker exec command.

edited Dec 24, 2020 at 11:17

answered Dec 21, 2020 at 19:02

Sandeep

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4 Comments

D86658 Over a year ago

It's a typo, corrected it. Still doesn't work.

D86658 Over a year ago

The error is container not found since containerId is empty when passed into sudo docker exec command

Sandeep Over a year ago

Do not store it in a seperate variable, pass it directly to docker exec command like so sudo docker exec -i $(sudo docker ps | grep 'tests_service_image' | colrm 13) bash

Raman Sailopal Over a year ago

echo $containerid to ensure you have an actual id in the variable.

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