fold is a Unix command used for making a file with long lines more readable on a limited width computer terminal by performing a line wrap. Most Unix terminals have a default screen width of 80, and therefore reading files with long lines could get annoying. The fold command puts a line feed every X characters if it does not reach a new line before that point. If the argument is set, the fold command allows the user to set the maximum length of a line.

History

The utility first appeared in 1BSD of 1977 and was originally written by Bill Joy. fold is part of the X/Open Portability Guide since issue 4 of 1992. It was inherited into the first version of POSIX.1 and the Single Unix Specification. The version of bundled in GNU coreutils was written by David MacKenzie. The command is available as a separate package for Microsoft Windows as part of the UnxUtils collection of native Win32 ports of common GNU Unix-like utilities.

Example

As a usage example, to fold a file named to have a maximum of 50 characters per line, one could run the following command: