sed Commands Cheatsheet — Stream Edit, Find & Replace

sed commands cheatsheet.

Find-and-replace and line surgery from the command line. Tap any command to copy it.

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Substitute (find & replace)

sed 's/old/new/' file.txtReplace the first match on each line

sed 's/old/new/g' file.txtReplace all matches on each line

sed 's/old/new/gi' file.txtReplace all, case-insensitive

sed -i 's/old/new/g' file.txtEdit the file in place

sed -i.bak 's/old/new/g' file.txtEdit in place, keep a .bak backup

sed 's|/old/path|/new/path|g' fileUse | as the delimiter for paths

Print, delete & select

sed -n '5p' file.txtPrint only line 5

sed -n '5,10p' file.txtPrint lines 5 through 10

sed '5d' file.txtDelete line 5

sed '/pattern/d' file.txtDelete every line matching a pattern

sed '$d' file.txtDelete the last line

sed -n '/start/,/end/p' file.txtPrint a range between two patterns

Insert, append & tidy

sed 's/^/ /' file.txtIndent every line by four spaces

sed 's/[[:space:]]*$//' file.txtStrip trailing whitespace

sed '/^$/d' file.txtRemove blank lines

sed '3i\new line' file.txtInsert a line before line 3

sed '3a\new line' file.txtAppend a line after line 3

sed -e 's/a/b/' -e 's/c/d/' fileApply several edits in one pass

By default sed prints to the screen and leaves your file untouched — add -i to edit in place. On macOS, -i requires an argument: use sed -i '' 's/old/new/g' file for no backup.

The substitute command does most of the work

sed is a "stream editor" — it reads text line by line and applies edits. The one command you'll use ninety percent of the time is substitute: s/old/new/ replaces text, and adding the g flag makes it replace every occurrence on a line instead of just the first. So sed 's/colour/color/g' fixes every instance on every line. The delimiter doesn't have to be a slash — when you're editing file paths, s|/old|/new| avoids a mess of escaped slashes.

Editing files in place, safely

By default sed prints the result and leaves the original file alone, which is great for previewing. To actually change the file, add -i (in place). The safe habit is -i.bak, which edits the file but first saves the original as file.bak — cheap insurance against a regex that matched more than you intended. A subtle gotcha: macOS (BSD) sed needs an explicit backup suffix, even an empty one, written as sed -i '' '...', whereas GNU sed on Linux is happy with a bare -i.

Working with specific lines

Beyond search-and-replace, sed can target lines by number or pattern. sed -n '5,10p' prints just lines 5 to 10 (the -n suppresses the default output so only the printed lines show), sed '5d' deletes line 5, and sed '/pattern/d' deletes every line matching a pattern — a quick way to strip blank lines or comments. For column-oriented data and arithmetic rather than line edits, reach for awk; to find the lines first, combine sed with grep.

FAQ

How do I find and replace text in a file with sed?

Use sed -i 's/old/new/g' file.txt. The s is substitute, g replaces all matches on each line, and -i writes the change back to the file. Use -i.bak to keep a backup first.

What does the g flag do in sed?

Without g, sed's substitute replaces only the first match on each line; with g it replaces every match on the line. Add i (as in s/old/new/gi) to also ignore case.

sed commands cheatsheet.

The substitute command does most of the work

Editing files in place, safely

Working with specific lines

FAQ

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