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· dos2unix · line-endings · linux · macos · command-line

Convert Windows line endings to Unix with dos2unix (2026)

Windows uses CRLF line endings, Unix uses LF — and the mismatch breaks shell scripts, configs, and diffs. dos2unix converts them in place; on Debian/Ubuntu it's now its own package (no more tofrodos). Includes a recursive batch and a sed fallback.

TL;DR — dos2unix file.txt rewrites a file’s CRLF (Windows) line endings to LF (Unix) in place. Install it with sudo apt install dos2unix. No dos2unix? sed -i 's/\r$//' file.txt does the same.

A 2008 note that pointed at the tofrodos package. On modern Debian/Ubuntu dos2unix is its own package now — simpler. The rest still applies: CRLF vs LF mismatches are a perennial nuisance.

Why it matters

DOS/Windows ends each line with CR+LF (\r\n); Unix/Linux/macOS use just LF (\n). A file authored on Windows and run on Linux carries stray \r characters that cause:

  • #!/bin/bash^M: bad interpreter when running a script.
  • Configs and .env files where a value silently gains a trailing \r.
  • Diffs and grep matching things that look identical but aren’t.

Install

sudo apt install dos2unix        # Debian / Ubuntu (its own package now)
sudo dnf install dos2unix         # Fedora
brew install dos2unix             # macOS

Convert

dos2unix script.sh

It converts in place. Keep a copy under a new name if you want the original:

dos2unix -n script.sh script.unix.sh

The reverse exists too — unix2dos file.txt adds CRLF back (e.g. for a file a Windows tool insists on).

Batch a whole tree

Convert every shell script under the current directory:

find . -type f -name '*.sh' -exec dos2unix {} +

dos2unix skips binary files it detects, so a broad find . -type f is usually safe — but scope it with -name when you can.

No dos2unix installed? Use sed

Strip the trailing CR with sed (in place with -i):

sed -i 's/\r$//' file.txt

Or with tr (writes to a new file — tr can’t edit in place):

tr -d '\r' < dosfile.txt > unixfile.txt

Check what you’ve got

file script.sh
script.sh: Bourne-Again shell script, ASCII text, with CRLF line terminators

“with CRLF line terminators” is the tell. cat -A file shows ^M at each line end.

FAQ

macOS sed says “invalid command code”

BSD sed (macOS) needs an argument after -i: sed -i '' 's/\r$//' file.txt. Or just brew install dos2unix and avoid the difference.

Git keeps reintroducing CRLF

That’s Git’s core.autocrlf / .gitattributes, not the file itself. Set * text=auto eol=lf in .gitattributes to normalise on commit.

Does this change the file’s encoding too?

No — line endings and character encoding are independent. For UTF-8/Latin-1 conversion see iconv.

Summary

  • dos2unix file — CRLF → LF, in place. unix2dos for the reverse.
  • Install: sudo apt install dos2unix (now its own package).
  • Batch: find . -name '*.sh' -exec dos2unix {} +.
  • Fallback: sed -i 's/\r$//' file (sed -i '' … on macOS).