How do I determine if a terminal is color-capable?

termcap, terminal, terminfo, unix

Solution

A friend pointed me towards tput(1), and I cooked up this solution:

#!/bin/sh

# ack-wrapper - use tput to try and detect whether the terminal is
#               color-capable, and call ack-grep accordingly.

OPTION='--nocolor'

COLORS=$(tput colors 2> /dev/null)
if [ $? = 0 ] && [ $COLORS -gt 2 ]; then
    OPTION=''
fi

exec ack-grep $OPTION "$@"

which works for me. It would be great if I had a way to integrate it into ack, though.

Problem

I would like to change a program to automatically detect whether a terminal is color-capable or not, so when I run said program from within a non-color capable terminal (say M-x shell in (X)Emacs), color is automatically turned off. I don't want to hardcode the program to detect TERM={emacs,dumb}. I am thinking that termcap/terminfo should be able to help with this, but so far I've only managed to cobble together this (n)curses-using snippet of code, which fails badly when it can't find the terminal: ``` #include <stdlib.h> #include <curses.h> int main(void) { int colors=0; initscr(); start_color(); colors=has_colors() ? 1 : 0; endwin(); printf(colors ? "YES\n" : "NO\n"); exit(0); } ``` I.e. I get this: ``` $ gcc -Wall -lncurses -o hep hep.c $ echo $TERM xterm $ ./hep YES $ export TERM=dumb $ ./hep NO $ export TERM=emacs $ ./hep Error opening terminal: emacs. $ ``` which is... suboptimal.

Original source