`sed` Find, replace and edit text in a stream

Reads text line by line, applies editing commands, and prints the result. Most often used to replace one piece of text with another, or to print or delete chosen lines, in a file or in piped output.

Synopsis

sed [OPTION]... 'COMMAND' [FILE]...
sed [OPTION]... -e 'COMMAND' [-f SCRIPTFILE] [FILE]...

Common options

Option or form	What it does
`-n`	Print only what a p command selects. Without it, sed prints every line
`-e command`	Add an editing command. Repeat -e to run several commands in order
`-f file`	Read the editing commands from a file
`-E, -r`	Use extended regular expressions, so ( ), + and \| work without backslashes. macOS and GNU both accept -E
`-i extension`	Edit the file in place. The extension is a backup suffix. macOS needs it as a separate argument, even an empty one ('')
`-I extension`	BSD and macOS only. Like -i, but treats all files as one continuous stream, so line numbers do not restart for each file

Examples

Replace the first match on each line

sed 's/pear/plum/' words.txt

plum
apple
plum
fig
apple
apple

Print only lines 2 to 3

sed -n '2,3p' notes.txt

beta error
gamma

Delete lines that match a pattern

sed '/error/d' notes.txt

alpha
gamma
Beta again
delta

Drop the header row of a CSV file

sed '1d' data.csv

ana,red,7
bo,blue,3
cy,red,9
dee,blue,3

Swap the first two CSV columns

sed -E 's/^([^,]*),([^,]*)/\2,\1/' data.csv

team,name,score
red,ana,7
blue,bo,3
red,cy,9
blue,dee,3

Edit a file in place and keep a backup

sed -i.bak 's/ERROR/FAIL/' app.log

Notes

In-place editing differs. GNU sed uses -i with no argument, as in sed -i 's/a/b/' file. macOS and BSD sed need an argument after -i, so that form fails there. On macOS: sed -i '' 's/a/b/' file works, and so does sed -i.bak 's/a/b/' file.
The portable way is sed -i.bak 's/a/b/' file. It works on macOS, BSD and GNU, and leaves file.bak as a backup. Delete the backup afterwards if you do not need it.
-i changes the file with no undo. Run the command without -i first to check the output, or keep a backup suffix.
Without the g flag, s/old/new/ replaces only the first match on each line. Add g to replace every match: s/old/new/g. Add I to ignore case: s/old/new/I works on macOS and GNU.
macOS sed is stricter than GNU sed. Commands such as 1i text on one line fail, and the backslash form \+ did not match on macOS. Use -E with +, and put i, a and c text on a new line after a backslash.

sed Find, replace and edit text in a stream

Synopsis

Common options

Examples

Notes

See also

`sed` Find, replace and edit text in a stream