Shell Programming and Scripting

Is there a POSIX compatible way of getting the number of columns in a tty? On Linux, I can do something like:

Code:

stty -a  | awk -F'[ ;]' '/columns/ { print $9 }'

But will that work on AIX, Solaris, etc?

Not sure about POSIX compliance but you might try that one which seems to work for me under Solaris and Linux:

Code:

LC_ALL=C stty -a  | grep columns | sed -e 's/.*columns //' -e 's/;.*$//' -e 's/= //'

stty is available on AIX, Solaris, HP-UX. However, IEEE std 1003.1-2008 POSIX) states that the ouput format is unspecified by the standard. This means that your method of parsing the output which you showed us may not work on all platforms.

Don't have access to Solaris at the moment. Would you mind posting the output from 'stty', please!

What do you think about jlligare's solution, above? What about with TERMCAP?

I guess you have never used a tty. There is no standard way to obtain columns or rows. There are lots of situations still in existence where it cannot be done. Most true terminals never had a way to inform the host about parameters like that because columns were pretty much locked to 80. A real teletype can't even reasonably have a notion of rows. It can't back up to the "top", you might have ripped off the paper. And how far it can go down depends only on how much paper is left. Real teletypes always had exactly 80 columns though. The tty driver was designed for real teletypes. HP had a super printing terminal that could support up to 132 "columns", (but we used the term "print positions"). It used pin feed style paper. You varied the columns by changing the paper. But the host could not enquire about paper size. Posix does not require that stty know about columns.

It is not part of POSIX.1, but most shells initialize a COLUMNS variable.