This tutorial explains Linux “fold” command, options and its usage with examples.
Wrap input lines in each FILE (standard input by default), writing to standard output. This breaks the lines to have a maximum of x width column position (or bytes).
fold [ -bs ] [-w width | -width] [file]
Count width in bytes rather than column positions.
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.
A path name of a text file to be folded. If no file operands are specified, the standard input will be used.
1. Given the contents of file abc, fold works as follows if width is 20:
$ cat abc This is a brief message to the Control Unit group. The new hp is now on-line. To send prints to it, type lj filename. If you have questions contact Sys. Adm. (x480). The printer is located in the stock room. $ fold -w 20 abc This is a brief me ssage to the Control Unit group. The new hp is n ow on-line. To send prints to it, type l j filename. If you have que stions contact Sys. Adm. (x480). The printer is located in the stock room.
2. For processing large no. of files to set them to width of 65(say), we use shell program
for i in *.txt do fold -sw 65 $i > $i.output done
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