On Mon, Jul 09, 2018 at 09:41:32AM -0400, Dan Ritter wrote:
> On Mon, Jul 09, 2018 at 09:08:17AM -0400, Greg Wooledge wrote:
> > On Sun, Jul 08, 2018 at 01:08:59PM +1000, Zenaan Harkness wrote:
> > > With a bash fn like:
> > > ttyGetNum () { return $(tty | grep -oE '[0-9]+$') ; }
> > >
> > > Then something like this will id your current tty:
> > > ttyGetNum; export Xorg_vt=vt$?
> >
> > Ewwwww!
> >
> > The return status of a shell function is NOT intended to be used this way.
> > It's analogous to the exit status of a shell command. It's a single
> > byte, unsigned, so you can only return 0 to 255. It's intended to convey
> > success or failure, not to carry an actual data payload.
> >
> > I recommend that you switch to using a regular variable for this purpose.
> > I happen to like "r". With a regular variable, you're not restricted to
> > integers from 0 to 255, and you retain the ability to convey succss/failure
> > through the return code.
> >
> > As an aside, you can save the call to GNU grep by simply stripping the
> > leading "/dev/tty" from the output of tty using a shell parameter
> > expansion:
> >
> > ttyGetNum() {
> > local t
> > t=$(tty) || return 1
> > [[ $t = /dev/tty+([0-9]) ]] || return 1
> > r=${t#/dev/tty}
> > }
> >
> > if ttyGetNum; then export Xorg_vt=vt"$r"; fi
> >
>
> fgconsole returns the current virtual terminal number.
> chvt switches to a specified virtual terminal.
Sweet!
> These are from package kbd.
Was already installed by me :)
And this will satisfy Dan's objection to a perfectly good use of
"return" values ;D
