How to Automatically Insert Line Breaks into SSH2 Public Keys

This guide will demonstrate how to use simple bash commands to insert line breaks at the correct locations (every 64 characters) in your SSH2 public keys.

Steps to Insert Line Breaks Automatically

Step 1: Prepare Your Key

Save your SSH2 public key to a file if it's not already in one. Suppose the key is saved as key.pub.

Step 2: Use fold Command to Insert Line Breaks

The fold command is a simple utility for wrapping lines in a text file to a specified width. For SSH2 public keys, we will wrap lines to 64 characters.

1. Open Terminal.

2. Run the following command:

fold -w 64 key.pub > formatted_key.pub

This command takes the input file key.pub, wraps the lines at 64 characters, and outputs the result to formatted_key.pub.

Step 3: Verify the Output Check that the new file formatted_key.pub has the correct formatting with:

cat formatted_key.pub

Ensure that line breaks are placed correctly without breaking the key structure.

Additional Tips

• Backup Your Original Key: Always make a backup of your original SSH key before modifying it.

• Editing Manually: If further adjustments are needed, you can use a text editor like vi or nano. For example, you can open vi and use commands within the editor to make manual adjustments if the automatic process does not meet specific needs.