* Christian Brauner: > +.\" Copyright (C) 2018 Christian Brauner <christian@xxxxxxxxxx> The text seems to be largely derived from rt_sigqueueinfo, so I'm not sure if this appropriate here. > +the null signal (0) can be used to check if a process with a given > +PID exists. What does this mean if hte process is identified by file descriptor? > +.PP > +The optional > +.I info > +argument specifies the data to accompany the signal. > +This argument is a pointer to a structure of type > +.IR siginfo_t , > +described in > +.BR sigaction (2) > +(and defined by including > +.IR <sigaction.h> ). > +The caller should set the following fields in this structure: > +.TP > +.I si_code > +This must be one of the > +.B SI_* > +codes in the Linux kernel source file > +.IR include/asm-generic/siginfo.h , > +with the restriction that the code must be negative > +(i.e., cannot be > +.BR SI_USER , > +which is used by the kernel to indicate a signal sent by > +.BR kill (2)) > +and cannot (since Linux 2.6.39) be Obsolete reference in this context. > +.TP > +.B ESRCH > +The process or process group does not exist. > +Note that an existing process might be a zombie, > +a process that has terminated execution, but > +has not yet been > +.BR wait (2)ed > +for. Again: What does this mean if the process identified by a descriptor? Does a process in zombie state exist in this sense or not? Thanks, Florian
