Previous: kubectl for CKAD - exercise 10 - copy from browser, paste into Vim, indent

In this exercise, we will learn how to search and replace text within a Vim document. We will be using the final testdep.yaml file created in the previous exercise.

Scenario 1: Basic Search and Replace

Change the mountPath: from /data/redis to /opt/redis

Open the testdep.yaml file from the previous exercise in Vim

vim testdep.yaml

The yaml should look like this:

apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    app: testdep
  name: testdep
spec:
  replicas: 1
  selector:
    matchLabels:
      app: testdep
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: testdep
    spec:
      containers:
      - image: nginx:alpine
        name: nginx
        volumeMounts:
        - name: redis-storage
          mountPath: /data/redis
      volumes:
      - name: redis-storage
        emptyDir: {}
        resources: {}
status: {}

Basic search and replace

Search and replace pattern:

:%s/searchtext/replacementtext/gc

Let’s break this down:

  • %s/ perform a substitution, the % means to perform the substitution across all lines in the file
  • searchtext text to search for
  • / delimiter
  • replacementtext replacement text
  • / delimiter
  • g global, replace all occurrences of searchtext everywhere in the document
  • c confirm, ask for confirmation before replacing the text. You can omit it if you want to replace all found searchtext occurrences

To search for data and replace it with opt, use the following command in Vim (in NORMAL mode, after pressing ESC):

:%s/data/opt/gc

Vim will now highlight the first occurrence of ‘data’, and at the bottom of the screen ask:

replace with opt (y/n/a/q/l/^E/^Y)?

The most used operations:

  • Press y to replace the current occurrence.
  • Press n to skip the current occurrence and move to the next.

Rest of the operations:

  • Press a to replace all occurrences without asking for confirmation.
  • Press q to quit the replace process.
  • Press l to replace the current occurrence and quit the replace process.
  • Press ^E or ^Y to scroll the screen up or down, respectively.

Use whichever operation you need, so the mountPath in your file changes to /opt/redis.

Write (save) the document

ESC                    # 'ESC'ape from INSERT mode 
:w testdep.yaml        # 'w'rite (save) the document

Apply the changes, to check if the yaml is correct - directly from inside Vim

If you have already set up the bash variable / shortcut ka in the previous exercises use it like this

:!$ka -f %             # Run `kubectl apply` directly from inside Vim, % references the current file name

Otherwise, you can run kubectl apply

:!kubectl apply -f %

Scenario 2: Escaping special characters

Sometimes the text we want to search for contains special characters like /. We can escape these characters with a backslash \ in the search pattern.

Let’s change /opt/redis back to /data/redis.

In Vim, execute:

:%s/\/opt\/redis/\/data\/redis/gc

Here we are using \/ to escape / in the searched text, using the slashes after :%s and redis as delimiters (:%s/ …redis/…redis/gc ) Again, with gc Vim will ask for confirmation before replacing text.

Write (save) the document

ESC                    # 'ESC'ape from INSERT mode 
:w testdep.yaml        # 'w'rite (save) the document

Replace the running deployment, to check if the yaml is correct - directly from inside Vim

If you have already set up the bash variables / shortcuts kr and $f0 in the previous exercises use it like this

:!$kr -f % $f0            # Run `kubectl replace` from inside Vim

Otherwise, you can run kubectl replace

:!kubectl replace -f % --force --grace-period 0

Scenario 3: Using an alternative delimiter

When we need to replace text containing forward slashes, instead of escaping / with \/, we can change the delimiter in our search and replace pattern. Common choices include %, # or +.

Let’s replace /data/redis with /mnt/redis using % as a delimiter.

:%s%/data/redis%/mnt/redis%gc

Here, we are using % instead of / as the delimiter for the search and replace pattern, which makes it easier to work with paths or other text containing slashes.

Again, Vim will ask for confirmation before replacing text.

Write (save) the document

ESC                    # 'ESC'ape from INSERT mode 
:w testdep.yaml        # 'w'rite (save) the document

Replace the running deployment, to check if the yaml is correct - directly from inside Vim

Scenario 4: Search and replace only part of a line

Sometimes, you only want to replace part of a line, for example, only the value after a key. Let’s say we want to change the name of the volume mount from redis-storage to redis-volume.

In your testdep.yaml, you have:

    spec:
      containers:
      - image: nginx:alpine
        name: nginx
        volumeMounts:
        - name: redis-storage
          mountPath: /data/redis
      volumes:
      - name: redis-storage
        emptyDir: {}
        resources: {}
status: {}

We only want to change storage, not the whole redis-storage

:%s/name: redis-\zs.*/volume/gc

Let’s analyze the command:

  • %s/: substitute in all lines
  • name: redis-: search for text name: redis-
  • \zs: This is a special sequence that marks the start of the match. Everything before \zs is used to locate the line, but not included in the replacement.
  • .*: Match all the rest of the characters on the line
  • /volume: replace the matched text after name: redis- with volume.
  • gc: global, and ask for confirmation

Vim will highlight the first occurrence of text after name: redis-, and ask for confirmation. Press a to replace all occurrences without asking for confirmation.

Now your file should contain:

    spec:
      containers:
      - image: nginx:alpine
        name: nginx
        volumeMounts:
        - name: redis-volume
          mountPath: /data/redis
      volumes:
      - name: redis-volume
        emptyDir: {}
        resources: {}
status: {}

Write (save) the document

ESC                    # 'ESC'ape from INSERT mode 
:w testdep.yaml        # 'w'rite (save) the document

Replace the running deployment, to check if the yaml is correct - directly from inside Vim

Congratulations!

You’ve now learned how to perform basic and more advanced search and replace operations in Vim. Practice these techniques to become more efficient at editing YAML manifests and other text files.