How to monitor the running i/o statistics of an application

The traditional, portable, commonly-used way is that the parent process watches over its children.

The basic primitives are the wait and waitpid system calls. When a child process dies, the parent process receives a SIGCHLD signal, telling it it should call wait to know which child died and its exit status. The parent process can instead choose to ignore SIGCHLD and call waitpid(-1, &status, WNOHANG) at its convenience.

To monitor many processes, you would either spawn them all from the same parent, or invoke them all through a simple monitoring process that just calls the desired program, waits for it to terminate and reports on the termination (in shell syntax: myprogram; echo myprogram $? >>/var/run/monitor-collector-pipe). If you're coming from the Windows world, note that having small programs doing one specialized task is a common design in the Unix world, the OS is designed to make processes cheap.

There are many process monitoring (also called supervisor) programs that can report when a process dies and optionally restart it and far more besides: Monit, Supervise, Upstart, …

The manpage reveals the answer. You will need tmux 1.4 (released Dec. 2010) or better.

Press Ctrl+B then enter the command:

:setw monitor-silence 30

To identify all quiet windows in the session, apply the setting to all windows:

:setw -g monitor-silence 30