Exploring sed - Linux Commands

#linux

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:

Terminal window
sed [options] 'command' file

Replace a string in a file:

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

Options

OptionDescription
-nSuppresses automatic output, useful when you only want specific lines
-eAllows multiple commands to be executed
-iModifies the file in place (saves changes directly to the file)
-rEnables 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:

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

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

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

2. Delete Lines

You can delete specific lines from a file:

Terminal window
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:

Terminal window
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:

Terminal window
sed --help
# or
man sed

Resources

Ten sed command examples

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

Thank you

Thank you for your time and for reading this!