Problem with non blocking fifo in bash

Question

Hi! I'm running a few Team Fortress 2 servers and I want to write a little management script.

Basically the TF2 servers are a fg process which provides a server console, so I can start the server, type status and get an answer from it:

***@purple:~/tf2$ ./start_server_testing 
Auto detecting CPU
Using AMD Optimised binary.
Server will auto-restart if there is a crash.

Console initialized.
[bla bla bla]
Connection to Steam servers successful.
   VAC secure mode is activated.

status

hostname: Team Fortress
version : 1.0.6.1/15 3883 secure
udp/ip  :  ***.***.133.31:27600
map     : ctf_2fort at: 0 x, 0 y, 0 z
players : 0 (2 max)

# userid name uniqueid connected ping loss state adr

Great, now I want to create a script which sends the command sm_reloadadmins to all my servers. The best way I found to do this is using a fifo named pipe. Now what I want to do is having this pipe readonly and non blocking to the server process, so I can write into the pipe and the server executes it, but still I want to write via console one the server, so if I switch back to the fg process of the server and I type status I want an answer printed.

I tried this (assuming serverfifo is mkfifo serverfifo):

./start_server_testing < serverfifo

Not working, the server won't start until something is written to the pipe.

./start_server_testing <> serverfifo

Thats actually working pretty good, I can see the console output of the server and I can write to the fifo and the server executes the commands, but I can't write via console to the server anymore. Also, if I write 'exit' to the pipe (which should end the server) and I'm running it in a screen the screen window is getting killed for some reason (wtf why?).

I only need the server to read the fifo without blocking AND all my keyboard input on the server itself should be send to the server AND all server ouput should be written to the console.

Is that possible? If yes, how?

Answer 1

I realize this isn't an answer in the same vein as you were pursuing, but you can probably do this using Gnu Screen.

Screen is a program that makes a pseudo-TTY. You can use its ability to let you share a screen session. This way, you can be logged in to the server inside of screen, and your script can share that session, send a command which you can see, and then stop sharing. The process to get screen set up to allow sharing sessions is described here. It requires root access, but I'm presuming you have that if you're running a TF2 server.

Once you get the setuid process set up and have the server prompt inside of screen, you can have your script log in to the relevant box, connect to screen, send the desired command to the server, send Ctrl-A,d to disconnect from screen, and then logout.