When working with text files across different operating systems, one common issue is the difference in how line endings are represented. Windows uses CRLF (\r\n) while Unix/Linux systems use LF (\n). This can cause problems in scripts, code, or data files if not handled correctly.
What Are CRLF and LF?
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CRLF (Carriage Return + Line Feed): Windows-style line ending. Two characters:
\r\n. -
LF (Line Feed): Unix/Linux-style line ending. One character:
\n.
Why Convert CRLF?
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Ensure compatibility of scripts and configuration files on Unix/Linux.
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Avoid issues in version control systems like Git, where inconsistent line endings can cause unnecessary diffs.
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Maintain proper formatting when sharing files across platforms.
How to Detect CRLF in Files
Use the file command:
file filename.txt
If the output mentions “CRLF,” the file uses Windows line endings.
Convert CRLF to LF Using Terminal Commands
1. Using dos2unix
The easiest way:
dos2unix filename.txt
This converts CRLF to LF in place.
If you don’t have dos2unix installed:
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On Debian/Ubuntu:
sudo apt-get install dos2unix
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On macOS (with Homebrew):
brew install dos2unix
2. Using sed
sed -i 's/\r$//' filename.txt
This command removes the \r (carriage return) at the end of each line.
3. Using tr
tr -d '\r' < inputfile > outputfile
Removes all carriage returns, writing the result to a new file.
Convert LF to CRLF (Unix to Windows)
Sometimes you need to add CRLF endings:
unix2dos filename.txt
Or with sed:
sed 's/$/\r/' filename.txt > outputfile.txt
Automate Conversion in Scripts
To batch convert all .txt files in a directory from CRLF to LF:
for file in *.txt; do dos2unix "$file"; done
Understanding and converting CRLF line endings is essential for cross-platform compatibility. Using simple terminal tools like dos2unix, sed, or tr, you can easily handle these conversions and avoid common pitfalls in file handling.