fold —
fold long lines for finite width output device
fold |
[-bs] [-w
width] [file ...] |
fold is a filter which folds the contents of the
specified files, or the standard input if no files are specified, breaking the
lines to have a maximum of 80 display columns.
The options are as follows:
-b- Count width in bytes rather than column
positions.
-s- If an output line would be broken after a non-blank character but contains
at least one blank character, break the line earlier, after the last blank
character. This is useful to avoid line breaks in the middle of words, if
possible.
-w
width- Specifies a line width to use instead of the default of 80.
Unless -b is specified, a backspace
character decrements the column position by one, a carriage return resets
the column position to zero, and a tab advances the column position to the
next multiple of eight.
LC_CTYPE- The character encoding locale(1). It
decides which byte sequences form characters and what their display width
is. If unset or set to “C”, “POSIX”, or an
unsupported value, each byte except backspace, tab, newline, and carriage
return is treated as a character of display width 1.
The fold utility exits 0 on success,
and >0 if an error occurs.
The fold utility is compliant with the
IEEE Std 1003.1-2008 (“POSIX.1”)
specification.
The fold utility first appeared in
1BSD. It was rewritten for
4.3BSD-Reno to improve speed and modernize style. The
-b and -s options were added
to NetBSD 1.0 for IEEE Std 1003.2
(“POSIX.2”) compliance.
Bill Joy wrote the original version of
fold on June 28, 1977. Kevin
Ruddy rewrote the command in 1990, and J. T.
Conklin added the missing options in 1993.
Traditional roff(7) output semantics,
implemented both by GNU nroff and by
mandoc(1), only uses a single backspace for
backing up the previous character, even for double-width characters. The
fold backspace semantics required by POSIX mishandles
such backspace-encoded sequences, breaking lines early. The
fmt(1) utility provides similar functionality
and does not suffer from that problem, but isn't standardized by POSIX.