How to Use the sed Command for Text Editing

Published 2026-08-05 · Learn Linux

The sed command (stream editor) reads text and applies editing instructions. Its most common job is find-and-replace: sed 's/old/new/g' file replaces every old with new. It prints the result to the screen, or you can write it back to the file with -i.

Substitute text with s/old/new/

The substitution command has the form s/pattern/replacement/. By default it changes only the first match on each line; add g to change every match.

$ sed 's/cat/dog/g' pets.txt

Edit the file in place with -i

sed prints to stdout by default. Add -i to edit the file directly. On macOS use -i "" to skip creating a backup copy.

$ sed -i 's/<H1>/<h1>/g' index.html

Target specific lines

Prefix the command with a line number or range. 2d deletes line 2, 1,5d deletes lines 1 through 5, and /pattern/d deletes every line that matches.

$ sed '2d' list.txt

$ sed '/^#/d' config.conf

The last example removes every comment line that starts with #, which is handy for stripping config files.

Print only matching lines with -n

Use -n to suppress normal output and p to print only what matches. This works like a focused grep.

$ sed -n '/error/p' app.log

Chain edits with -e

Apply several instructions in one pass with -e. This replaces old with new and deletes blank lines in a single read of the file.

$ sed -e 's/foo/bar/g' -e '/^$/d' file.txt

sed is one of the three classic text tools alongside awk. The sed reference page documents the full command language.