Create file using 'touch ./tmp.$$', file tmp.3941 is created, why?
 

Create file using 'touch ./tmp.$$', file tmp.3941 is created, why?

Because $$ is a bash-variable, it hold the PID of
the process invoking it, in other words, the pid of
the shell you used to touch. It will vary in other
shells ;)


Cheers,
Tink