What is the difference between SIGSTOP and SIGTSTP?
Solution 1:
Both signals are designed to suspend a process which will be eventually resumed with SIGCONT
. The main differences between them are:
SIGSTOP
is a signal sent programmatically (eg:kill -STOP pid
) whileSIGTSTP
(for signal - terminal stop) may also be sent through thetty
driver by a user typing on a keyboard, usually Control-Z.SIGSTOP
cannot be ignored.SIGTSTP
might be.
Solution 2:
/usr/include/x86_64-linux-gnu/bits/signum.h
#define SIGSTOP 19 /* Stop, unblockable (POSIX). */
#define SIGTSTP 20 /* Keyboard stop (POSIX). */
Solution 3:
SIGSTOP can't be ignored by the targetted process.
A good example of that is the video player mpv
, it can ignore SIGTSTP
but not SIGSTOP
.
You can test with a video running :
kill -SIGTSTP $(pidof mpv)
and
kill -SIGSTOP $(pidof mpv)
Of course kill -SIGCONT $(pidof mpv)
to resume playing.