FM / pid

/var/spool/postfix/pid

Name	Size	Mode	Actions
inet.smtp	0	0600	edit dl rm
master.pid	33	0600	edit dl rm
unix.bounce	0	0600	edit dl rm
unix.cleanup	0	0600	edit dl rm
unix.defer	0	0600	edit dl rm
unix.local	0	0600	edit dl rm
unix.retry	0	0600	edit dl rm
unix.smtp	0	0600	edit dl rm

Edit: /var/spool/postfix/pid/master.pid (33B)

cmd: