Getting the size of the terminal in a portable way

ruby-talk
1

I'd like to be able to determine the width of the terminal in which my
command-line tool is running.

I made a quick program to find out the value of TIOCGWINSZ on my
system (Mac OS X 10.4.8, running on Intel):

#include <sys/ioctl.h>
#include <unistd.h>

int main(int argc, char *argv[])
{
  printf("%d\n", TIOCGWINSZ);
  return 0;
}

The value is 1074295912 (0x40087468). Then I used the following Ruby
code based on something I found in the archives:

TIOCGWINSZ = 0x40087468
str = [0, 0, 0, 0].pack('SSSS')
if STDIN.ioctl(TIOCGWINSZ, str) >= 0
  rows, cols, xpixels, ypixels = str.unpack("SSSS")
  p rows, cols, xpixels, ypixels
else
  puts "Unable to get window size"
end

This returns the correct values:

[55, 132, 792, 770]

That is, 55 rows, 132 columns. I'd like to know if there's a more
portable way of doing this... About the only semi-portable way I can
think of is wrapping this up in a C extension; at least that way
(most) people can compile it locally. Suggestions?

Cheers,
Greg

2

HighLine can do this:

require "highline/system_extensions.rb"
cols, rows = HighLine::SystemExtensions.terminal_size

Hope that helps.

James Edward Gray II

···

On Mar 5, 2007, at 11:25 AM, Greg Hurrell wrote:

I'd like to be able to determine the width of the terminal in which my
command-line tool is running.

I made a quick program to find out the value of TIOCGWINSZ on my
system (Mac OS X 10.4.8, running on Intel):

#include <sys/ioctl.h>
#include <unistd.h>

int main(int argc, char *argv)
{
  printf("%d\n", TIOCGWINSZ);
  return 0;
}

The value is 1074295912 (0x40087468). Then I used the following Ruby
code based on something I found in the archives:

TIOCGWINSZ = 0x40087468
str = [0, 0, 0, 0].pack('SSSS')
if STDIN.ioctl(TIOCGWINSZ, str) >= 0
  rows, cols, xpixels, ypixels = str.unpack("SSSS")
  p rows, cols, xpixels, ypixels
else
  puts "Unable to get window size"
end

This returns the correct values:

[55, 132, 792, 770]

That is, 55 rows, 132 columns. I'd like to know if there's a more
portable way of doing this... About the only semi-portable way I can
think of is wrapping this up in a C extension; at least that way
(most) people can compile it locally. Suggestions?

3

Thanks, James. That seems to cover just about all platforms, although
it introduces another dependency or two (HighLine itself, plus
HighLine's own dependencies). I guess that's the way it is though...

Cheers,
Greg

···

On 5 mar, 18:34, James Edward Gray II <j...@grayproductions.net> wrote:

HighLine can do this:

require "highline/system_extensions.rb"
cols, rows = HighLine::SystemExtensions.terminal_size

4

I use highline in a bunch of internal projects for CLI gui's, it totally rocks(thx JEGII&Gregory!). But I want these to be standalone gems with no dependencies so I embed highline in my own gems. Its only a few files and easy to embed so it makes sense to ship it with the gem that needs it.

Cheers-

-- Ezra Zygmuntowicz-- Lead Rails Evangelist
-- ez@engineyard.com
-- Engine Yard, Serious Rails Hosting
-- (866) 518-YARD (9273)

···

On Mar 5, 2007, at 10:35 AM, Greg Hurrell wrote:

On 5 mar, 18:34, James Edward Gray II <j...@grayproductions.net> > wrote:

HighLine can do this:

require "highline/system_extensions.rb"
cols, rows = HighLine::SystemExtensions.terminal_size

Thanks, James. That seems to cover just about all platforms, although
it introduces another dependency or two (HighLine itself, plus
HighLine's own dependencies). I guess that's the way it is though...

Cheers,
Greg