fold(1) General Commands Manual fold(1)
NAME
fold - Breaks or wraps lines in a file
SYNOPSIS
fold [-bs] [-w width | -width] [file...]
The fold command wraps lines in the specified files. If a file is not specified, standard input is the default. All lines are wrapped to
meet the maximum width specified.
STANDARDS
Interfaces documented on this reference page conform to industry standards as follows:
fold: XCU5.0
Refer to the standards(5) reference page for more information about industry standards and associated tags.
OPTIONS
Specifies that width be counted in bytes rather than in column positions. Using the -b option does not limit lines to LINE_MAX bytes.
Breaks (or wraps) a line if a segment of the line contains a blank character in the first width column position (or bytes). This enables
the line to meet width constraints. If a blank character is not in the correct width column position, the -s option has no affect on that
input line. Specifies the maximum width to use when lines are wrapped in column positions (or bytes if the -b option is specified).
Either -w width or -width is acceptable input where width is the number of column positions (or bytes). The default value is 80.
DESCRIPTION
The fold command is a filter that wraps lines from the specified input files or standard input to a maximum of width (or bytes, if the -b
option is specified). The fold command wraps lines by inserting a newline character into the output so that each output line is the maxi-
mum column positions or bytes specified. A line cannot be broken in the middle of a character.
The fold command is often used to send text files to line printers that truncate, rather than wrap, lines wider than the printer is able to
print (usually 80 or 132 column positions).
If the <backspace>, <tab>, or <carriage return> characters are encountered in the input, and the -b option is not specified, these charac-
ters are treated specially: The current count of line width is decremented by one, although the count never becomes negative. The fold
command does not insert a newline character immediately before or after any backspace character. Each tab character encountered advances
the column position pointer to the position of the next tab stop. Tab stops are at each column position number, such that number modulo 8
equals 1. The current count of the line width is set to zero (0). The fold command does not insert a newline immediately before or after
any carriage return.
[Tru64 UNIX] The fold command possibly affects underlining in a file.
EXIT STATUS
The fold command returns the following values: All input files were successfully processed. [Tru64 UNIX] A usage error occurred. [Tru64
UNIX] An input file cannot be opened. The fold command continues processing the other input files specified on the command line.
EXAMPLES
The fold command can be used to prepare files to be joined side-by-side with the paste command. For example, the contents of two files, az
and AZ follows:
aaaa bbbb cccc dddd eeee ffff gggg hhhh iiii jjjj kkkk llll mmmm nnnn oooo pppp qqqq rrrr ssss tttt uuuu vvvv wwww xxxx yyyy zzzz
AAAA BBBB CCCC DDDD EEEE FFFF GGGG HHHH IIII JJJJ KKKK LLLL MMMM NNNN OOOO PPPP QQQQ RRRR SSSS TTTT UUUU VVVV WWWW XXXX YYYY ZZZZ
To display the az and AZ files side-by-side, use the following command line: fold -w 32 az > az2; fold -w 32 AZ > AZ2; paste -d" " az2 AZ2
Executing the previous command line results in the following output:
aaaa bbbb cccc dddd eeee ffff gg AAAA BBBB CCCC DDDD EEEE FFFF GG gg hhhh iiii jjjj kkkk llll mmmm GG HHHH IIII JJJJ KKKK LLLL MMMM nnnn
oooo pppp qqqq rrrr ssss tt NNNN OOOO PPPP QQQQ RRRR SSSS TT tt uuuu vvvv wwww xxxx yyyy zzzz TT UUUU VVVV WWWW XXXX YYYY ZZZZ
ENVIRONMENT VARIABLES
The following environment variables affect the execution of fold: Provides a default value for the internationalization variables that are
unset or null. If LANG is unset or null, the corresponding value from the default locale is used. If any of the internationalization vari-
ables contain an invalid setting, the utility behaves as if none of the variables had been defined. If set to a non-empty string value,
overrides the values of all the other internationalization variables. Determines the locale for the interpretation of sequences of bytes
of text data as characters (for example, single-byte as opposed to multibyte characters in arguments) and for the determination of the
width in column positions each character would occupy on a constant-width font output device. Determines the locale for the format and
contents of diagnostic messages written to standard error. Determines the location of message catalogues for the processing of LC_MES-
SAGES.
SEE ALSO
Commands: cut(1), expand(1), paste(1)
Standards: standards(5)
fold(1)