signal generation

yash_legend · 04-22-2018, 07:20 AM

how to generate SIGHUP signal?
In which case signal generation gets failed?

TB0ne · 04-22-2018, 07:33 AM

Quote:

Originally Posted by yash_legend

how to generate SIGHUP signal? In which case signal generation gets failed?

Read the "Question Guidelines" link in my posting signature; unless you provide details and ask a clear question, there's little we can do to help you. Also, doing basic research first before posting is a good thing.
https://en.wikipedia.org/wiki/SIGHUP

A sighup can be MANY different things, depending on the terminal, shell, program, language, or what the programmer has DECIDED it needs to be.

BW-userx · 04-22-2018, 08:12 AM

Quote:

On POSIX-compliant platforms, SIGHUP ("signal hang up") is a signal sent to a process when its controlling terminal is closed

so, by that definition, I'd easily say,

1. how to generate SIGHUP signal?
A: Close your terminal.
2. In which case signal generation gets failed?
A: When the terminal does not close.

first glance thoughts on that subject, mind you.

https://en.wikipedia.org/wiki/SIGHUP

chrism01 · 04-22-2018, 06:50 PM

You can get a list of signal names & numbers from the shell

Code:

 kill -l
 1) SIGHUP	 2) SIGINT	 3) SIGQUIT	 4) SIGILL	 5) SIGTRAP
 6) SIGABRT	 7) SIGBUS	 8) SIGFPE	 9) SIGKILL	10) SIGUSR1
11) SIGSEGV	12) SIGUSR2	13) SIGPIPE	14) SIGALRM	15) SIGTERM
16) SIGSTKFLT	17) SIGCHLD	18) SIGCONT	19) SIGSTOP	20) SIGTSTP
21) SIGTTIN	22) SIGTTOU	23) SIGURG	24) SIGXCPU	25) SIGXFSZ
26) SIGVTALRM	27) SIGPROF	28) SIGWINCH	29) SIGIO	30) SIGPWR
31) SIGSYS	34) SIGRTMIN	35) SIGRTMIN+1	36) SIGRTMIN+2	37) SIGRTMIN+3
38) SIGRTMIN+4	39) SIGRTMIN+5	40) SIGRTMIN+6	41) SIGRTMIN+7	42) SIGRTMIN+8
43) SIGRTMIN+9	44) SIGRTMIN+10	45) SIGRTMIN+11	46) SIGRTMIN+12	47) SIGRTMIN+13
48) SIGRTMIN+14	49) SIGRTMIN+15	50) SIGRTMAX-14	51) SIGRTMAX-13	52) SIGRTMAX-12
53) SIGRTMAX-11	54) SIGRTMAX-10	55) SIGRTMAX-9	56) SIGRTMAX-8	57) SIGRTMAX-7
58) SIGRTMAX-6	59) SIGRTMAX-5	60) SIGRTMAX-4	61) SIGRTMAX-3	62) SIGRTMAX-2
63) SIGRTMAX-1	64) SIGRTMAX

rtmistler · 04-23-2018, 11:40 AM

A minor addition to chrism01's post is that either using the library function call kill(2), or the command line call for kill(1), you do not have to send just SIGKILL, you can send any of the signals. I believe (didn't double check) that there is also just a signal(2) library call which does the same thing, just appears clearer due to the name, and I think part of both the kill call options are only that since SIGKILL is so common, they made that the default.

I'm not that historical with Unix or System V if that's where it originated, but ran into someone using code to send a different signal other than KILL but still using the kill() function. It confused me until I looked up the man page for kill.

Figure out if you're using a function call or the command line and then chose your option to send the signal.

Man pages ... is there nothing they can't do?