dos2unix

dos2unix is a command-line utility designed to convert text files between DOS/Windows line endings (CRLF) and Unix-like line endings (LF). The package often includes a companion tool, unix2dos, for performing the reverse conversion. It is widely used on Unix-like systems such as Linux and BSD, and is also available on macOS and Windows through ports and compatibility layers like Cygwin, MSYS2, or Windows Subsystem for Linux. As open-source software, it is maintained by multiple contributors across platforms.

The primary purpose of dos2unix is to normalize line endings in text files to match the conventions of the target environment. It typically modifies only the line-ending characters, leaving the file content otherwise intact. This can prevent issues in scripts, configuration files, and source code that rely on consistent line endings. Some implementations provide safeguards for binary files or large files and may offer options to preserve timestamps or create backups.

Typical usage involves either in-place conversion or writing to a separate output file. For example, dos2unix filename converts the file in place, while dos2unix -n infile outfile performs a two-file conversion to avoid altering the original until the operation completes. Similarly, unix2dos performs the reverse transformation.

While there are multiple implementations and variants, the core functionality remains the same: translating between CRLF and LF line endings to improve portability and reduce cross-platform issues. See also line ending, carriage return, and text versus binary modes in file handling.