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sed Replacement Builder Guide

Build a sed command to replace text, delete matching lines or print only matches, with in-place editing and backups.

sed is a command that edits lines of text. sed Replacement Builder writes a command for replacement, deletion, or printing matching lines; it does not run the command or touch your files.

Build a harmless replacement

Leave What should sed do? on Replace text, enter cat as Pattern, and dog as Replacement. Leave Files empty and Global (g) and Extended regex (-E) checked. Command should show sed -E s/cat/dog/g. With no file, sed would read standard input. For example, piping the test line cat cat through this command would produce dog dog.

For a real file, use a disposable copy first. Edit in place (-i) modifies the named file, and Keep a .bak backup only takes effect when in-place editing is on. If Files is empty and in-place editing is enabled, the tool asks for a file. File names and globs are inserted as typed—not shell-escaped—so inspect the entire command before running it, and quote file names with spaces yourself. Do not paste untrusted file text into a shell command.

Where your input goes

Processing runs in your browser. The tool does not upload your input to ilham.dev.

For more background, read Linux Command Line Tasks Without Surprises.

Questions you might have

Is an in-place edit reversible?
When both Edit in place and Keep a .bak backup are checked, the generated command uses -i.bak so sed normally writes a .bak copy of each file. Check that copy yourself before relying on it; without a backup there is no tool-provided undo.
What does the I flag do?
It makes the pattern match without regard to case. It is a GNU extension, so it works with GNU sed on Linux but not with the old BSD sed on macOS.
Why does it quote the expression in single quotes?
The builder shell-quotes the sed expression when its characters require it; this simple cat example needs no quotes. The Files field is not quoted by the builder; a path with spaces or shell metacharacters needs manual review.