The signals listed below may be available for use with kill. When known constant, numbers and default behavior are shown.
Name Num Action Description () ()
0 0 n/a exit code indicates if a signal may be sent ALRM 14 exit HUP 1 exit INT 2 exit KILL 9 exit this signal may not be blocked PIPE 13 exit POLL exit PROF exit TERM 15 exit USR1 exit USR2 exit VTALRM exit STKFLT exit may not be implemented PWR ignore may exit on some systems WINCH ignore CHLD ignore URG ignore TSTP stop may interact with the shell TTIN stop may interact with the shell TTOU stop may interact with the shell STOP stop this signal may not be blocked CONT restart continue if stopped, otherwise ignore ABRT 6 core FPE 8 core ILL 4 core QUIT 3 core SEGV 11 core TRAP 5 core SYS core may not be implemented EMT core may not be implemented BUS core core dump may fail
XCPU core core dump may fail XFSZ core core dump may fail
Mostly used in real life are 15 (default), 1 (allowing cleanup) and 9 (as last resort). But read here why you should avoid 9 if possible: Useless use of kill -9. Its better to try in this order and only use the next if the previous failed: 15 (TERM) -> 2 (INT) -> 1 (HUP) -> 9 (KILL).