Date: 2012mar10 OS: Linux Q. Why do I get a different number each time I list /proc/self ? A. When you do:

cd /proc ls -l self

Example output:

lrwxrwxrwx 1 root root 64 Mar 9 23:32 self -> 17520/

A new process is started to run ls. Its the process id for ls you are seeing. From the shell you can do:

echo $$

to see your process id. Or:

PID=$$ echo My PID is $PID

in a shell script. From a C program do:

pit_t pid = getpid();

Still /proc/self is cool and useful. From a program you can read things from its folder.