sed commands

15 commands, each with a one-line explanation. Click a command to copy it, or its title for details.

Commands 15 shown

Substitute first match per line

sed 's/foo/bar/' file.txt

Replace the first occurrence of 'foo' with 'bar' per line
linux
Substitute all matches (global)

sed 's/foo/bar/g' file.txt

Replace every occurrence per line with the /g flag
linux
In-place edit

sed -i 's/old/new/g' config.cfg

Modify file in-place (no backup); on macOS add empty string: -i ''
linux
In-place edit with backup

sed -i.bak 's/old/new/g' file.txt

Edit in-place and save original as file.txt.bak
linux
Delete matching lines

sed '/^#/d' config.txt

Delete all comment lines starting with #
linux
Delete blank lines

sed '/^[[:space:]]*$/d' file.txt

Remove all empty or whitespace-only lines
linux
Print specific line numbers

sed -n '10,20p' file.txt

Print lines 10 through 20 only (suppress default output with -n)
linux
Print lines matching pattern

sed -n '/ERROR/p' app.log

Print only lines that match ERROR
linux · debug
Insert line before match

sed '/^server_name/i # Added by deploy script' nginx.conf

Insert a comment line before every server_name directive
linux
Append line after match

sed '/^\[defaults\]/a ansible_python_interpreter=/usr/bin/python3' ansible.cfg

Append a setting line after the [defaults] header
linux
Case-insensitive substitution

sed 's/error/ERROR/gI' file.txt

GNU sed /I flag for case-insensitive match
linux
Multiple expressions

sed -e 's/foo/bar/g' -e 's/baz/qux/g' file.txt

Apply multiple substitutions in one command
linux
Strip leading/trailing whitespace

sed 's/^[[:space:]]*//;s/[[:space:]]*$//' file.txt

Trim leading and trailing whitespace from each line
linux
Address range substitution

sed '5,15s/DEBUG/INFO/g' app.log

Apply substitution only to lines 5 through 15
linux
Extract value from key=value file

sed -n 's/^DB_HOST=//p' .env

Print the value of DB_HOST from a .env file
linux