> И добрая традиция оставлять pid-файл при падении.

man pidfile

DESCRIPTION
     The pidfile family of functions allows daemons to handle PID files.  It
     uses flopen(3) to lock a pidfile and detect already running daemons.
     The pidfile_open() function opens (or creates) a file specified by the
     path argument and locks it.  If pidptr argument is not NULL and file can
     not be locked, the function will use it to store a PID of an already
     running daemon or -1 in case daemon did not write its PID yet. 

2005 год.
man procdesc

DESCRIPTION
     procdesc is a file-descriptor-oriented interface to process signalling
     and control, which supplements historic UNIX fork(2), kill(2), and
     wait4(2) primitives with new system calls such as pdfork(2), pdkill(2),
     and pdwait4(2).  procdesc is designed for use with capsicum(4), replacing
     process identifiers with capability-oriented references.  However, it can
     also be used independently of capsicum(4), displacing PIDs, which may
     otherwise suffer from race conditions.  Given a process descriptor, it is
     possible to query its conventional PID using pdgetpid(2).

2011 год.