Permalink
Switch branches/tags
Nothing to show
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
63 lines (48 sloc) 2.42 KB
Demonstrations of killsnoop, the Linux ftrace version.
What signals are happening on my system?
# ./killsnoop
Tracing kill()s. Ctrl-C to end.
COMM PID TPID SIGNAL RETURN
postgres 2209 2148 10 0
postgres 5416 2209 12 0
postgres 5416 2209 12 0
supervise 2135 5465 15 0
supervise 2135 5465 18 0
^C
Ending tracing...
The first line of output shows that PID 2209, process name "postgres", has
sent a signal 10 (SIGUSR1) to target PID 2148. This signal returned success (0).
kilsnoop traces the kill() syscall, which is used to send signals to other
processes. These signals can include SIGKILL and SIGTERM, both of which
ultimately kill the target process (in different fashions), but the signals
may also include other operations, including checking if a process still
exists (signal 0). To read more about signals, see "man -s7 signal".
killsnoop can be useful to identify why some processes are abruptly and
unexpectedly ending (also check for the OOM killer in dmesg).
The -s option can be used to print signal names instead of numbers:
# ./killsnoop -s
Tracing kill()s. Ctrl-C to end.
COMM PID KILLED SIGNAL RETURN
postgres 2209 2148 SIGUSR1 0
postgres 5665 2209 SIGUSR2 0
postgres 5665 2209 SIGUSR2 0
supervise 2135 5711 SIGTERM 0
supervise 2135 5711 SIGCONT 0
bash 27450 27450 0 0
[...]
On the last line: there wasn't a nice signal name for signal 0, so just numeric
0 is printed. You'll see signal 0's used to check if processes still exist.
Use -h to print the USAGE message:
# ./opensnoop -h
USAGE: killsnoop [-ht] [-d secs] [-p PID] [-n name] [filename]
-d seconds # trace duration, and use buffers
-n name # process name to match
-p PID # PID to match on kill issue
-t # include time (seconds)
-s # human readable signal names
-h # this usage message
eg,
killsnoop # watch kill()s live (unbuffered)
killsnoop -d 1 # trace 1 sec (buffered)
killsnoop -p 181 # trace kill()s issued to PID 181 only
See the man page and example file for more info.