NAME

fold - Breaks or wraps lines in a file

SYNOPSIS

fold [-bs] [-w 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. 

FLAGS

-bSpecifies that width be counted in bytes rather than in column positions.  Using the -b flag does not limit lines to LINE_MAX bytes. 

-sBreaks (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 flag has no affect on that input line. 

-w widthSpecifies the maximum width to use when lines are wrapped in column positions (or bytes if the -b flag is specified).  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 flag is specified).  The fold command wraps lines by inserting a newline character into the output so that each output line is the maximum 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 flag is not specified, these characters are treated specially:

<backspace>
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. 

<tab>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. 

<carriage-return>
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. 

Note that the fold command possibly affects underlining in a file. 

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 previous two files side-by-side, use the following command line:

fold -w 32 az > az2; fold -w 32 AZ > AZ2; paste -d" " az2 AZ2

Using 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

EXIT VALUES

The fold command returns the following values:

0All input files were successfully processed. 

1A usage error occurred. 

2An input file cannot be opened.  The fold command continues processing the other input files specified on the command line. 

RELATED INFORMATION

Commands:  cut(1), expand(1), unexpand(1), paste(1).