K
Q

Question

remove the first white line returned by a command line

12/27/2019

I'm using kubernetes, and I want to get podname from the app name. Here is the command I use.

POD=$(kubectl get pods -l app=influxdb-local -o custom-columns=:metadata.name -n influx)

Then I would like to use the result in:

kubectl exec -it -n influx $POD -- influx -username user -password "user" -execute "CREATE DATABASE db"

but the first line is empty, and the second line contains pod name, so the second command doesn't work.

How should I remove the first white line ?

-- Juliatzin

bash

kubectl

kubernetes

12/27/2019

Add --no-headers to skip the header line

kubectl get pods -l app=influxdb-local -o custom-columns=:metadata.name -n influx --no-headers

Using the flag -o custom-columns=<header-name>:<field> will let you customize the output.

Example with resource name, under header NAME

kubectl get pods -o custom-columns=NAME:metadata.name

output

NAME
myapp-5b77df6c48-dbvnh
myapp-64d5985fdb-mcgcn
httpd-9497b648f-9vtbl

Empty header name: you used the flag as -o custom-columns=:metadata.name - the first line is the header line, but with an empty header.

the proper solution to omit the header line is by using the flag --no-headers

kubectl get pods -o custom-columns=NAME:metadata.name --no-headers

Example output

myapp-5b77df6c48-dbvnh
myapp-64d5985fdb-mcgcn
httpd-9497b648f-9vtbl

-- Jonas

Source: StackOverflow