How to Use the sed Command on Linux for Text Editing

Understanding the sed Command

• 💡 sed is a powerful stream editor on Linux used for searching, replacing, and modifying text directly from the terminal without opening a full editor.
• ⚙️ The basic syntax involves sed [options] 'command' filename, where command specifies the action to perform.

Basic Substitution and Global Replacement

• 🎯 The s/old/new/ command is used for substituting text, replacing the first occurrence of 'old' with 'new' on each line.
• 🌍 To replace all occurrences of a pattern on a line, use the global flag: s/old/new/g.
• ⚠️ By default, sed only shows changes in the output; the original file remains unchanged.

In-Place Editing and Backups

• 💾 The -i option allows for in-place editing, modifying the file directly.
• 🔙 To create a backup of the original file before editing, use -i.bak, which appends .bak to the original filename.

Targeting Specific Lines and Deleting Lines

• 📍 You can apply commands to specific lines by prefixing the command with the line number (e.g., 6s/old/new/).
• ↔️ A line range can be specified using a comma between line numbers (e.g., 2,3s/old/new/) to apply changes to multiple lines.
• 🗑️ The d command is used to delete specific lines from the file, and -i is needed to make this deletion permanent.