Why Do Windows and Unix Use Different Line Endings? Understanding \n vs \r

What are \n and \r?

In the ASCII table, \n is the line‑feed (LF) character with code 10, which moves the cursor down one line. \r is the carriage‑return (CR) character with code 13, which returns the cursor to the beginning of the current line.

Historical background

Early teleprinters such as the Teletype Model 33 printed characters at about 10 cps. When a line finished, the machine needed 0.2 seconds to return the carriage to the left margin; during that time incoming characters could be lost. To avoid loss, the device used two control characters: CR to move the carriage home and LF to advance the paper.

How modern systems use them

When computers adopted the teleprinter conventions, some designers argued that a single character would suffice, leading to differing line‑ending conventions:

MS‑DOS/Windows: CR + LF (\r\n)

Unix/Linux: LF only (\n)

Classic macOS (pre‑OS X): CR only (\r)

Because of these differences, a file created on one platform may appear as a single long line on another, or show stray “^M” characters.

Practical impact

Opening a Unix‑style file in Windows Notepad shows all text on one line; opening a Windows‑style file on Unix may display a visible carriage‑return symbol. Some editors accept only \r\n, while others accept either character.

Conversion tools

On Linux, the unix2dos command converts LF line endings to CR + LF, and dos2unix does the reverse. When transferring files via FTP, using ASCII mode may automatically translate line endings, so binary mode should be chosen to preserve the original bytes.

Example code

Typical C code that prints a line with Windows‑style termination:

printf('hello world!
');