How to find out if emacs is running inside GUI or terminal

How to find out if emacs is running inside GUI or terminal

[Louis-Guillaume Gagnon]

Hi,

Is there a way to find out within emacs if it is running in a GUI or inside
a terminal (i.e. -nw switch specified on the cli)  using Elisp?

The reason is I would like to take different actions in my ~/.emacs
depending on the situation.

Thanks,

glg

Re: How to find out if emacs is running inside GUI or terminal

[Bob Proulx]

Louis-Guillaume Gagnon wrote:
> Is there a way to find out within emacs if it is running in a GUI or inside
> a terminal (i.e. -nw switch specified on the cli)  using Elisp?
> 
> The reason is I would like to take different actions in my ~/.emacs
> depending on the situation.

Yes.  Use 'window-system' to determine this.  Example:

  (if window-system
      (setq mouse-yank-at-point t))

And to head off complaints about the example, it is only an example.
I am aware of 'fboundp'.

Bob

Re: How to find out if emacs is running inside GUI or terminal

[Óscar Fuentes]

Bob Proulx <bob@proulx.com> writes:

> Louis-Guillaume Gagnon wrote:
>> Is there a way to find out within emacs if it is running in a GUI or inside
>> a terminal (i.e. -nw switch specified on the cli)  using Elisp?
>> 
>> The reason is I would like to take different actions in my ~/.emacs
>> depending on the situation.
>
> Yes.  Use 'window-system' to determine this.  Example:
>
>   (if window-system
>       (setq mouse-yank-at-point t))
>
> And to head off complaints about the example, it is only an example.
> I am aware of 'fboundp'.

I'll complain about something else, then :-)

C-h v window-system

  [...]

  Use of this variable as a boolean is deprecated.  Instead,
  use `display-graphic-p' or any of the other `display-*-p'
  predicates which report frame's specific UI-related capabilities.

So your example should be

(if (display-graphic-p)
  ....

There are several display-*-p functions for querying about specific
features for a display.

Re: How to find out if emacs is running inside GUI or terminal

[Bob Proulx]

Óscar Fuentes wrote:
> Bob Proulx writes:
> >   (if window-system
> >       (setq mouse-yank-at-point t))
> > And to head off complaints about the example, it is only an example.
> > I am aware of 'fboundp'.
> 
> I'll complain about something else, then :-)

:-)

> C-h v window-system
> 
>   [...]
> 
>   Use of this variable as a boolean is deprecated.  Instead,
>   use `display-graphic-p' or any of the other `display-*-p'
>   predicates which report frame's specific UI-related capabilities.

Deprecated!  I wish people would let the API mature and stabilize.  I
hadn't heard of the display-graphic-p functions yet.  Thanks for
mentioning them.

> So your example should be
> 
> (if (display-graphic-p)
>   ....
> 
> There are several display-*-p functions for querying about specific
> features for a display.

Sure.  Unless you happen to be using an older emacs that doesn't have
those newer functions.  I will have to look to see how long they have
been around.

Bob

RE: How to find out if emacs is running inside GUI or terminal

[Drew Adams]

> > There are several display-*-p functions for querying about specific
> > features for a display.
> 
> Sure.  Unless you happen to be using an older emacs that doesn't have
> those newer functions.  I will have to look to see how long they have
> been around.

Emacs 22, for `display-graphic-p', at least.

Re: How to find out if emacs is running inside GUI or terminal

[Eli Zaretskii]

> Date: Sun, 24 Nov 2013 18:30:26 -0800 (PST)
> From: Drew Adams <drew.adams@oracle.com>
> 
> > > There are several display-*-p functions for querying about specific
> > > features for a display.
> > 
> > Sure.  Unless you happen to be using an older emacs that doesn't have
> > those newer functions.  I will have to look to see how long they have
> > been around.
> 
> Emacs 22, for `display-graphic-p', at least.

No, it's Emacs 21.1; see NEWS.21.

RE: How to find out if emacs is running inside GUI or terminal

[Drew Adams]

> > Emacs 22, for `display-graphic-p', at least.
> No, it's Emacs 21.1; see NEWS.21.

Right; thanks for the correction.

Re: How to find out if emacs is running inside GUI or terminal

[Eli Zaretskii]

> Date: Sun, 24 Nov 2013 19:04:05 -0700
> From: Bob Proulx <bob@proulx.com>
> 
> > C-h v window-system
> > 
> >   [...]
> > 
> >   Use of this variable as a boolean is deprecated.  Instead,
> >   use `display-graphic-p' or any of the other `display-*-p'
> >   predicates which report frame's specific UI-related capabilities.
> 
> Deprecated!  I wish people would let the API mature and stabilize.  I
> hadn't heard of the display-graphic-p functions yet.  Thanks for
> mentioning them.

display-graphic-p (as well as the other display-*-p predicates) exist
since Emacs 21.1.  And window-system is deprecated approximately since
that time also.  So I think this deprecation is mature enough ;-)

> > There are several display-*-p functions for querying about specific
> > features for a display.
> 
> Sure.  Unless you happen to be using an older emacs that doesn't have
> those newer functions.

I very much doubt that you have such old Emacsen around.

Re: How to find out if emacs is running inside GUI or terminal

[Bob Proulx]

Eli Zaretskii wrote:
> Bob Proulx wrote:
> > Deprecated!  I wish people would let the API mature and stabilize.  I
> > hadn't heard of the display-graphic-p functions yet.  Thanks for
> > mentioning them.
> 
> display-graphic-p (as well as the other display-*-p predicates) exist
> since Emacs 21.1.  And window-system is deprecated approximately since
> that time also.  So I think this deprecation is mature enough ;-)

I guess since 21.1 is long enough. :-)

> > > There are several display-*-p functions for querying about specific
> > > features for a display.
> > 
> > Sure.  Unless you happen to be using an older emacs that doesn't have
> > those newer functions.
> 
> I very much doubt that you have such old Emacsen around.

Yes, unlikely.  Version 23 is the typically oldest one for me.  I am
using version 24 on my recent systems.  Although I do sometimes miss
version 18 which always seems like the best "old one" that I remember. :-)

Bob

Re: How to find out if emacs is running inside GUI or terminal

[Stefan Monnier]

> Is there a way to find out within emacs if it is running in a GUI or inside
> a terminal (i.e. -nw switch specified on the cli)  using Elisp?

Note that a single Emacs can run both with GUI frames and with terminal
frames at the same time.  E.g. you can start "emacs -nw" and then from
there you can M-x make-frame-on-display RET to open GUI frames.
Or you can run Emacs in "GUI mode", then do M-x server-mode RET, and
then use "emacsclient -t" from a terminal to open a terminal frame.


        Stefan