fold(1) manual page
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fold - filter for folding lines
fold [ -bs ] [ -w width
| -width ] [ file ... ]
SUNWcsu
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.
The following options are supported:
- -b
- Count 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), break 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
- Specify 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.
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.
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
See environ(5)
for descriptions of the
following environment variables that affect the execution of fold: LC_CTYPE
,
LC_MESSAGES
, and NLSPATH
.
The following exit values are returned:
- All input files were processed successfully.
- >0
- An error occurred.
cut(1)
,
pr(1)
, environ(5)
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.
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