Find out screen id

Question

I want to start a program with SSH using PHP, which works fine, but now I want to kill the screen with PHP, but the only thing I know is the name of the screen. How do I find out the screen ID (automatically)?

Answer 1

You can use the environment variable $STY to determine whether you're in a screen session and also what the name of the session is that you're inside.

Example

Initially we're sitting in a terminal window, not inside of a screen session.

$ echo $STY

$

Spin up a screen session:

$ screen -ls
There is a screen on:
    31543.tscrn (Detached)
1 Socket in /var/run/screen/S-saml.

Connect to it:

$ screen -r 31543.tscrn

Inside screen session:

$ echo $STY
31543.tscrn
$

Killing a session

With the name of the session you can kill it using screen.

$ screen -X -S tscrn kill

You can also use the number there too.

$ screen -X -S 31543 kill

Confirm that its been killed:

$ screen -ls
No Sockets found in /var/run/screen/S-saml.

Answer 2

Do you mean the screen program? screen -ls will list screen processes along with their screen name, prepended by the PID they are running from:

screen -S foo
screen -ls

There are screens on:
    8806.foo        (09/08/13 20:05:22)     (Attached)

You can use that to kill the process:

kill -15 $(screen -ls | grep '[0-9]*\.foo' | sed -E 's/\s+([0-9]+)\..*/\1/')

Alternatively, if you can identify the php process with ps, then it's parent id will be screen and you can kill that. pgrep -U <myusername> -f <name> will help find the php process you want to find (note the -f which searches the command arguments as well as the command name). You may be running more than one php script, so -f will be a better mechanism to match your process. <myusername> would be your username, <name> would be a string to match the process by. Then you can use ps -p <pid> -o ppid= to get the screen process ID and kill that.

kill -15 $( ps -p $(pgrep -U fooman -f foobar_process) -o ppid= )