Re: bulletproof way of finding size of terminal?

Ask the operating system.

#!/usr/bin/env perl

use strict;
use warnings;

chomp(my @lines = `stty -a`);
my ($rows, $columns);
for (@lines) {
    $rows = $1 if /rows (\d+);/;       # linux
    $rows = $1 if /(\d+) rows;/;       # FreeBSD
    $columns = $2 if /columns (\d+);/; # line
    $columns = $1 if /(\d+) columns;/; # FreeBSD
}

print "rows $rows columns $columns\n";
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Outputs;

rows 45 columns 118
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On my FreeBSD clone.

Comment on Re: bulletproof way of finding size of terminal? Select or Download Code

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Re^2: bulletproof way of finding size of terminal? by bcrowell2 (Friar) on Sep 01, 2007 at 01:14 UTC
Fantastic -- thanks, that's exactly what I needed. BTW, I think the $2 should have been a $1. It works for me on both Linux and FreeBSD. The following is what I ended up with. # Normally returns the number of columns on the output tty. # Return 0 if output isn't a tty. # Returns undef if it's unable to find the width. sub tty_columns { return 0 unless -t STDOUT; my $result; # The following works on linux, but seems to fail on freebsd. # It works properly if the user resizes the terminal window while th +e program is running. if (eval "require 'sys/ioctl.ph'") { eval { # All of the dies on the next few lines will be caught by the ev +al{}. die unless defined &TIOCGWINSZ; open(TTY, "+</dev/tty") or die; die unless ioctl(TTY, &TIOCGWINSZ, $winsize=''); my ($row, $col, $xpixel, $ypixel) = unpack('S4', $winsize); $result = $col; } } return $result if defined $result; # A less efficient fallback, should work on anything unixy. chomp(my @lines = `stty -a`); my ($rows, $columns); for (@lines) { $rows = $1 if /rows (\d+);/; # linux $rows = $1 if /(\d+) rows;/; # FreeBSD $columns = $1 if /columns (\d+);/; # linux $columns = $1 if /(\d+) columns;/; # FreeBSD } return $columns if defined $columns; # The following two methods give us a fighting chance on a non-POSIX + system. I don't use them as the defaults # because I don't want to introduce dependencies. # http://search.cpan.org/~kjalb/TermReadKey/ReadKey.pm # Term::ReadKey is not a standard Perl module, and may not be instal +led. If the user resizes the terminal # while the program is running, this will correctly reflect the resi +zing. eval 'use Term::ReadKey; my ($wchar, $hchar, $wpixels, $hpixels) = G +etTerminalSize(); $result=$wchar'; return $result if defined $result; # http://search.cpan.org/~nwclark/perl-5.8.8/lib/Term/ReadLine.pm # Term::ReadLine is a standard Perl module, but exists in different +implementations under the hood. On a Linux # system, it's implemented using Term::ReadLine::Gnu, which supports + get_screen_size(). On a default FreeBSD system, # however, the following won't work; you'd have to install the p5-Re +adLine-Gnu package to get support for this function. eval 'use Term::ReadLine; $term = new Term::ReadLine("foo"); my ($r, +$c)= Term::ReadLine::get_screen_size(); $result=$c'; return $result if defined $result; return undef; } [download]	[reply] [d/l]

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Re^2: bulletproof way of finding size of terminal?
by bcrowell2 (Friar) on Sep 01, 2007 at 01:14 UTC

Fantastic -- thanks, that's exactly what I needed. BTW, I think the $2 should have been a $1. It works for me on both Linux and FreeBSD. The following is what I ended up with.

# Normally returns the number of columns on the output tty.
# Return 0 if output isn't a tty.
# Returns undef if it's unable to find the width.
sub tty_columns {
  return 0 unless -t STDOUT;

  my $result;

  # The following works on linux, but seems to fail on freebsd.
  # It works properly if the user resizes the terminal window while th
+e program is running.
  if (eval "require 'sys/ioctl.ph'") {
    eval {
      # All of the dies on the next few lines will be caught by the ev
+al{}.
      die unless defined &TIOCGWINSZ;
      open(TTY, "+</dev/tty") or die;
      die unless ioctl(TTY, &TIOCGWINSZ, $winsize='');
      my ($row, $col, $xpixel, $ypixel) = unpack('S4', $winsize);
      $result = $col;
    }
  }
  return $result if defined $result;

  # A less efficient fallback, should work on anything unixy.
  chomp(my @lines = `stty -a`);
  my ($rows, $columns);
  for (@lines) {
      $rows = $1 if /rows (\d+);/;       # linux
      $rows = $1 if /(\d+) rows;/;       # FreeBSD
      $columns = $1 if /columns (\d+);/; # linux
      $columns = $1 if /(\d+) columns;/; # FreeBSD
  }
  return $columns if defined $columns;

  # The following two methods give us a fighting chance on a non-POSIX
+ system. I don't use them as the defaults
  # because I don't want to introduce dependencies.

  # http://search.cpan.org/~kjalb/TermReadKey/ReadKey.pm
  # Term::ReadKey is not a standard Perl module, and may not be instal
+led. If the user resizes the terminal
  # while the program is running, this will correctly reflect the resi
+zing.
  eval 'use Term::ReadKey; my ($wchar, $hchar, $wpixels, $hpixels) = G
+etTerminalSize(); $result=$wchar';
  return $result if defined $result;

  # http://search.cpan.org/~nwclark/perl-5.8.8/lib/Term/ReadLine.pm
  # Term::ReadLine is a standard Perl module, but exists in different 
+implementations under the hood. On a Linux
  # system, it's implemented using Term::ReadLine::Gnu, which supports
+ get_screen_size(). On a default FreeBSD system,
  # however, the following won't work; you'd have to install the p5-Re
+adLine-Gnu package to get support for this function.
  eval 'use Term::ReadLine; $term = new Term::ReadLine("foo"); my ($r,
+$c)= Term::ReadLine::get_screen_size(); $result=$c';
  return $result if defined $result;

  return undef;
}
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