How to get terminal dimensions without using curses or ncurses?

Ruby
1

I’d like to be able to print to terminal and do some reasonable
formatting, without going to the trouble of learning curses. I simply
need to know the dimensions of the terminal, but that info doesn’t
appear to be available in the ENV variables (which is what I’d
expected.) Is there a way to get this info?

Thanks,
Ken

2

Followup: I found this code, which is supposed to do the trick:

#!/usr/bin/env ruby

TIOCGWINSZ = 0x5413

def terminal_size
rows, cols = 25, 80
buf = [0, 0, 0, 0].pack(“SSSS”)
if STDOUT.ioctl(TIOCGWINSZ, buf) >= 0 then
rows, cols, row_pixels, row_pixels, col_pixels =
buf.unpack(“SSSS”)[0…1]
end
return [rows, cols]
end

print terminal_size

But when I run it, I get :

./term_size.rb:9:in ioctl': Inappropriate ioctl for device (Errno::ENOTTY) from ./term_size.rb:9:interminal_size’
from ./term_size.rb:15

This is on OS X 10.5, tried with both terminal and iterm. Any ideas?

Thanks,
Ken

3

Kenneth McDonald wrote:

     rows, cols, row_pixels, row_pixels, col_pixels =

/term_size.rb:9:in `ioctl’: Inappropriate ioctl for device
On Sep 25, 2008, at 5:33 PM, Kenneth McDonald wrote:

Do you have a command called infocmp available on OS X? Calling this
without a name will return the terminal capabilities of the currently
defined terminal. From this you can extract the lines and columns by
looking for lines# and cols# respectively.
The above command gets the information from the terminfo database and
there should be other implementations of it available if it is not on
your system.
I got the above command from the O’Reilly ‘termcap and terminfo’ book.

4

On Sep 25, 2008, at 5:33 PM, Kenneth McDonald wrote:

I’d like to be able to print to terminal and do some reasonable
formatting, without going to the trouble of learning curses. I
simply need to know the dimensions of the terminal, but that info
doesn’t appear to be available in the ENV variables (which is what
I’d expected.) Is there a way to get this info?

Sure:

$ cat term_size.rb
#!/usr/bin/env ruby -wKU

require “rubygems”
require “highline/system_extensions”

p HighLine::SystemExtensions.terminal_size
$ ruby term_size.rb
[80, 24]

You can look in that file of the source if you just want to see how
HighLine is doing that on various platforms.

James Edward G. II

5

On Thu, Sep 25, 2008 at 3:33 PM, Kenneth McDonald
[email protected] wrote:

I’d like to be able to print to terminal and do some reasonable formatting,
without going to the trouble of learning curses. I simply need to know the
dimensions of the terminal, but that info doesn’t appear to be available in
the ENV variables (which is what I’d expected.) Is there a way to get this
info?

It’s platform dependent, and curses has already done the hard work of
writing a uniform function call across various platforms. I’d
personally recommend going ahead and using just enough of curses to
get that function - you don’t need to bother with the rest of it.

martin

6

This looks very nice. Do you know where on OS X highline and its
documentation get installed, after a sudo gem install? Strangely, I
can’t find them easing using the OS X search features.

Thanks,
Ken

7

On Sep 25, 2008, at 8:11 PM, Kenneth McDonald wrote:

This looks very nice. Do you know where on OS X highline and its
documentation get installed, after a sudo gem install? Strangely, I
can’t find them easing using the OS X search features.

You can just read the source online:

http://highline.rubyforge.org/svn/trunk/highline/lib/highline/system_extensions.rb

Or just use this gem command to copy the source where you would like it:

gem unpack highline

Hope that helps.

James Edward G. II

8

Kenneth McDonald wrote:

I’d like to be able to print to terminal and do some reasonable
formatting, without going to the trouble of learning curses. I simply
need to know the dimensions of the terminal, but that info doesn’t
appear to be available in the ENV variables (which is what I’d
expected.) Is there a way to get this info?

Thanks,
Ken

There is code in Ruport that you could try.

http://stonecode.svnrepository.com/svn/ruport/ruport/trunk/lib/ruport.rb

Search down to “terminal_size”

9

On Sep 26, 2008, at 4:05 AM, Brian C. wrote:

There is code in Ruport that you could try.

http://stonecode.svnrepository.com/svn/ruport/ruport/trunk/lib/ruport.rb

Search down to “terminal_size”

Looks to me like Greg took that code right out of HighLine. :slight_smile:

James Edward G. II