12

I see from many place the follow command is used to check if a process exists, e.g.

killall -0 nginx

But from the documentation I can't see anything related to this argument, can anyone explain?

Teun Zengerink
  • 199
  • 5
  • 13
Howard
  • 2,135
  • 13
  • 48
  • 72

1 Answers1

18

man kill

If sig is 0, then no signal is sent, but error checking is still performed; this can be used to check for the existence of a process ID or process group ID.

killall kill processes by name instead of PID on Linux & BSD-based systems. In other Operating Systems (Solaris), the killall command is used to terminate all running processes.

Signal15
  • 952
  • 7
  • 29
quanta
  • 51,413
  • 19
  • 159
  • 217
  • 3
    Note: `killall` kills processes by name on Linux and BSD platforms. On other platforms (notable Solaris) is kills all processes (ie stops the server). – Chris S Oct 10 '12 at 13:31