FOLD(1) User Commands FOLD(1)

NAME

fold - filter for folding lines

SYNOPSIS

fold [-bs] [-w width | -width] [file]...

DESCRIPTION

The fold utility is a filter that will fold lines from its input
files, breaking the lines to have a maximum of width column positions
(or bytes, if the -b option is specified). Lines will be broken by
the insertion of a NEWLINE character such that each output line
(referred to later in this section as a segment) is the maximum width
possible that does not exceed the specified number of column
positions (or bytes). A line will not be broken in the middle of a
character. The behavior is undefined if width is less than the number
of columns any single character in the input would occupy.


If the CARRIAGE-RETURN, BACKSPACE, or TAB characters are encountered
in the input, and the -b option is not specified, they will be
treated specially:

BACKSPACE
The current count of line width will be
decremented by one, although the count never will
become negative. fold will not insert a NEWLINE
character immediately before or after any
BACKSPACE character.


CARRIAGE-RETURN
The current count of line width will be set to 0.
fold will not insert a NEWLINE character
immediately before or after any CARRIAGE-RETURN
character.


TAB
Each TAB character encountered will advance the
column position pointer to the next tab stop. Tab
stops will be at each column position n such that
n modulo 8 equals 1.

OPTIONS

The following options are supported:

-b
Counts width in bytes rather than column
positions.


-s
If a segment of a line contains a blank character
within the first width column positions (or
bytes), breaks the line after the last such blank
character meeting the width constraints. If there
is no blank character meeting the requirements,
the -s option will have no effect for that output
segment of the input line.


-w width|-width
Specifies the maximum line length, in column
positions (or bytes if -b is specified). If width
is not a positive decimal number, an error is
returned. The default value is 80.

OPERANDS

The following operand is supported:

file
A path name of a text file to be folded. If no file operands
are specified, the standard input will be used.

EXAMPLES

Example 1: Submitting a file of possibly long lines to the line

printer


An example invocation that submits a file of possibly long lines to
the line printer (under the assumption that the user knows the line
width of the printer to be assigned by lp(1)):


example% fold -w 132 bigfile | lp

ENVIRONMENT VARIABLES

See environ(7) for descriptions of the following environment
variables that affect the execution of fold: LANG, LC_ALL, LC_CTYPE,
LC_MESSAGES, and NLSPATH.

EXIT STATUS

The following exit values are returned:

0
All input files were processed successfully.


>0
An error occurred.

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|CSI | enabled |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+

SEE ALSO

cut(1), pr(1), attributes(7), environ(7), standards(7)

NOTES

fold and cut(1) can be used to create text files out of files with
arbitrary line lengths. fold should be used when the contents of long
lines need to be kept contiguous. cut should be used when the number
of lines (or records) needs to remain constant.


fold is frequently used to send text files to line printers that
truncate, rather than fold, lines wider than the printer is able to
print (usually 80 or 132 column positions).


fold may not work correctly if underlining is present.

February 1, 1995 FOLD(1)