Replace value of a line in a yml with bash

Question

web:   image: nginx   volumes:     - "./app:/src/app"   ports:     - "3030:3000"     - "35729:35729" 

I would like to have a bash script to replace the nginx for an argument with bash script.

./script apache 

Will replace nginx for apache

Answer 1

You can use this: sed -r 's/^(\s*)(image\s*:\s*nginx\s*$)/\1image: apache/' file

Sample run:

$ cat file web:   image: nginx   volumes:     - "./app:/src/app"   ports:     - "3030:3000"     - "35729:35729" $ sed -r 's/^(\s*)(image\s*:\s*nginx\s*$)/\1image: apache/' file web:   image: apache   volumes:     - "./app:/src/app"   ports:     - "3030:3000"     - "35729:35729" 

To persist the changes into the file you can use in-place option like this:

$ sed -ri 's/^(\s*)(image\s*:\s*nginx\s*$)/\1image: apache/' file 

---

If you want it inside a script you can just put the sed command inside a script and execute it with $1 in sustitution.

$ vim script.sh  $ cat script.sh  sed -ri 's/^(\s*)(image\s*:\s*nginx\s*$)/\1image: '"$1"'/' file $ chmod 755 script.sh  $ cat file  web:   image: nginx   volumes:     - "./app:/src/app"   ports:     - "3030:3000"     - "35729:35729" $ ./script.sh apache $ cat file  web:   image: apache   volumes:     - "./app:/src/app"   ports:     - "3030:3000"     - "35729:35729" $ 

Answer 2

You could create your script.sh as follows:

#!/bin/bash # $1 image value you want to replace # $2 is the file you want to edit sed -i "" "/^\([[:space:]]*image: \).*/s//\1$1/" $2 

And then run: ./script.sh apache filename.yaml