How many tty and pts are running on my pc?

Question

I found that more pts can be created this way.

1. To reboot into text mode-tty1

2. to input startx to jump into gui mode.
   To enter terminal in the gui mode started from tty1 to inupt.

     tty    
     /dev/pts/0  
   

this gui is pts/0

3. to input ctrl+alt+f2 to jump into
   another text mode-tty2
4. to input startx to jump into gui mode, this gui is pts/1.

To enter terminal in the gui mode started from tty2 to inupt

    tty
    /dev/pts/1  

Now two gui modes can be created.
How to know how many tty and pts are running at the same time on my pc?

Every gui program--include virtual terminal in gui is the client(or say slave) of x-server(or say x window system) ,so it was called pesudo terminal slave.

Muru give me many new knowledge,maybe there is a wrong expression in muru's explaination.

In my opinion,the proper sentence would be that:
but that's an application program in X server started from the tty1, but also a pts.

Please see the discuss here on what is pts/0 and (:0.0) in linux when typing who am i

From the knowledge,i draw my conclusion.

It not only an X server started from the tty1, but also a pts.

Answer 1

this gui is pts/0

Um, nope. I'm not sure where you got pts/0 from, but that's an X server started from the tty1, it isn't pts/0. See this U&L post for more.

At any given time, by default, there are 6 TTYs with getty running on them (so that you can login there) - TTYs 1-6, which you can access using CtrlAltF1-F6. TTY 7 has the GUI started by default. On 16.04 and above, you can start more getty instances using:

systemctl start getty@ttyN

Replacing N with an appropriate number.

To find the number of pseudoterminals currently open, you can do:

ps -eo tty= | sort -u

ps -e lists all processes, and -o tty= lists the process TTYs without a header line. sort and get unique entries with -u. For example:

$ ps -eo tty= | sort -u
?
pts/0
pts/1
pts/2
tty1
ttyS0