How to truncate STDIN line length?

Question

I\'ve been parsing through some log files and I\'ve found that some of the lines are too long to display on one line so Terminal.app kindly wraps them onto the next line. Ho

Answer 1

This isn't exactly what you're asking for, but GNU Screen (included with OS X, if I recall correctly, and common on other *nix systems) lets you turn line wrapping on/off (C-a r and C-a C-r). That way, you can simply resize your terminal instead of piping stuff through a script.

Screen basically gives you "virtual" terminals within one toplevel terminal application.

Answer 2

Unless I'm missing the point, the UNIX "fold" command was designed to do exactly that:

$ cat file
the quick brown fox jumped over the lazy dog's back

$ fold -w20 file
the quick brown fox
jumped over the lazy
 dog's back

$ fold -w10 file
the quick
brown fox
jumped ove
r the lazy
 dog's bac
k

$ fold -s -w10 file
the quick
brown fox
jumped
over the
lazy
dog's back

Answer 3

Not exactly answering the question, but if you want to stick with Perl and use a one-liner, a possibility is:

$ perl -pe's/(?<=.{25}).*//' filename

where 25 is the desired line length.

Answer 4

The usual way to do this would be

perl -wlne'print substr($_,0,80)'

Golfed (for 5.10):

perl -nE'say/(.{0,80})/'

(Don't think of it as programming, think of it as using a command line tool with a huge number of options.) (Yes, the python reference is intentional.)

Answer 5

You can use a tied variable that clips its contents to a fixed length:

#! /usr/bin/perl -w

use strict;
use warnings
use String::FixedLen;

tie my $str, 'String::FixedLen', 4;

while (defined($str = <>)) {
    chomp;
    print "$str\n";
}

Answer 6

Pipe output to:

cut -b 1-LIMIT

Where LIMIT is the desired line width.