What is -:0 ?
 

In htop I can see something running with the name "-:0"

I only find this when running kde.

I am curious about what -:0 is.

My guess it is relates to the DISPLAY variable of X, which is basically the X session. If you were to Ctrl+Alt+F6 into a new terminal and startx from there (keeping your first one actice), or start some other X-based program that supports it (like steam), it would (should?) be assigned :1.

Truthfully, I'm extrapolating a little from your post, in trying to figure out exactly what you're asking. And I run xfce rather than kde. But htop would be showing the command line that started the processes it is tracking. I suspect that what you're referring to would be something that contains something similar to

some_command --display :0.0

In all probability some_command is expecting to utilize running X server, and you haven't set a DISPLAY environment variable. The DISPLAY would be where the Xserver is sending its graphic output - which is specified in three parts <hostname>:<display>.<screen> (where display and screen are zero-based sequences). When <hostname> hasn't been specified, it defualts to localhost

so, :0.0 is basically saying that some_command is to send its graphic output to the first (only?) available display used by the Xserver running locally.

For the real details (as opposed to what I cobbled together here) try typing
man X
in a terminal

Or, possibly I just answered a question you didn't ask

I think DISPLAY is an antiquated term, since many computers have multiple displays attached, and that number has nothing to do with them. It is tied to the X session rather than to a monitor.

(I wasn't trying to correct any of your info, just offering overall clarification.)

It seems to be related to KDE

It doesnt change when I startx in another getty.

Hi...

Where is this symbol located in htop? What word or category is it next to or under?

Regards...

Attached is a snapshot of htop in tree mode.

I am supposing now that it is part of KDE but it seems to be odd named handle for a procedure.

Hi...

The entry in question is from the KDE Display Manager and I'm pretty sure that "-:0" has to do with your display, as magicm mentioned. :)

Regards...

I would assume someone using a nickname borrowed from a Firesign Theater skit would consider "odd" provocative and possibly hilarious :D like a clean windshield or a full tank of gas.

And, BTW, didja take a look at the prow on that steamer? ;)

root@darkstar:~# ls -l /proc/1126/exe
lrwxrwxrwx 1 root root 0 Svi 16 15:25 /proc/1126/exe -> /usr/bin/xdm*

edit:
just to be clear, that is the pid of -:0 currently on my computer
checking this as root is required

edit2:
the name in htop is from /proc/$pid/cmdline
usually the first argument (as in *argv[0]) passed to a starting program is its name, but in this case it is not

KDM is the login screen provided by KDE. The :0 is absolutely the X session it is attached to (and why my Ctrl+Alt+F6 wouldn't add another :1, because KDM will only be used on the first X session, since all others will be logged in). I'm not sure why it is presented this way, but it is certainly no cause for alarm :)

@enorbit: -:0 sort of looks like one of those Paul Frank julius-the-monkey faces.

I thought maybe one of those bullies from Commie Martyrs High School was mossing me
or maybe it was the bees and the spiders again...