Exploring sed - Linux Commands

What is the sed Command in Linux?

The sed (stream editor) command in Linux is a powerful tool used for text manipulation. It can perform various text operations, such as substitution, deletion, and insertion, on files or streams of data. It is often used for automation in shell scripts to modify files or input without needing to open an editor.

Basic syntax:

sed [options] 'command' file

Replace a string in a file:

sed 's/old_string/new_string/' file.txt

Options

Option	Description
-n	Suppresses automatic output, useful when you only want specific lines
-e	Allows multiple commands to be executed
-i	Modifies the file in place (saves changes directly to the file)
-r	Enables extended regular expressions in the script

Common Use Cases

1. Substitution

The most common operation in sed is substitution, which replaces one string with another:

sed 's/old/new/' file.txt

To replace all occurrences on a line, use the g (global) flag:

sed 's/old/new/g' file.txt

2. Delete Lines

You can delete specific lines from a file:

sed '2d' file.txt    # Deletes line 2
sed '5,10d' file.txt # Deletes lines 5 through 10

3. Inserting or Appending Text

Insert or append text to specific lines:

sed '3i\Inserted text' file.txt    # Inserts "Inserted text" before line 3
sed '3a\Appended text' file.txt    # Appends "Appended text" after line 3

Additional Help

You can explore more by using the commands:

sed --help
# or
man sed

Resources

Ten sed command examples

15 Useful ‘sed’ Command Tips and Tricks for Linux SysAdmins

Thank you!

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