A signal is a message which can be sent to a running process. Signals can be initiated by programs, users, or administrators.

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Program behavior when kill -HUP is recieved?

Is there a way to find out what will program do when it receives kill signal HUP? Without simply running the command ofc :D For example, killall -HUP pppd will restart pppd killall -HUP firefox ...
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2answers
971 views

Process descendants

I'm trying to build a process container. The container will trigger other programs. For example - a bash script that launches running background tasks with '&' usage. The important feature I'm ...
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1answer
2k views

Can you specify a separate trap in a subshell created with ()?

I'm writing a script that starts a subshell to go off and do some work. In a special case, the script needs to tell the subshell to cleanly stop what it's doing and exit early. However, my ...
2
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2answers
504 views

What's the difference between the ^S and ^Z control characters inside a terminal?

When using a terminal emulator, one can stop the currently running program with either CTRL-Z or CTRL-S. What's the difference between these signals?
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2answers
1k views

how to trap a suspend a resume from a bash script

I have a bash script (on osx) running continuously, it currently traps and handles a terminate like so trap onshutdown TERM how can I make trap also handle suspend/resume like trap onsuspend ? ...
13
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2answers
19k views

How can I kill a <defunct> process whose parent is init?

Transmission is intermittently hanging on my NAS. If I send SIGTERM, it doesn't disappear from the process list and a <defunct> label appears next to it. If I send a SIGKILL, it still doesn't ...
31
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5answers
5k views

Timing out in a shell script

I have a shell script that's reading from standard input. In rare circumstances, there will be no one ready to provide input, and the script must time out. In case of timeout, the script must execute ...
4
votes
3answers
5k views

when does the system send a SIGTERM to a process?

My server program received a SIGTERM and stopped (with exit code 0). I am surprised by this, as I am pretty sure that there was plenty of memory for it. Under what conditions does linux (busybox) send ...
10
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1answer
6k views

How to suspend and resume processes like bash does

this question is a follow-up to: How to suspend and resume processes I have started firefox from a bash session in gnome-terminal. The process tree looks like this: $ ps -e -o pid,ppid,cmd -H 1828 ...
4
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3answers
325 views

What documentation shows the associated numbers for linux signals like SIGTERM and SIGKILL?

I can look around the internet and find that the associated number for SIGKILL is 9, but is there linux documentation (such as, a man page) showing the complete list of signals and their numbers?
7
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2answers
2k views

What causes various signals to be sent?

I sometimes get a little confused by all of the signals that an application can receive. As I understand it, an application has a default handler for each of these signals, but it can provide its own ...
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2answers
416 views

Is nohup indefinite?

If I run a program with an infinite loop with nohup, will the program run indefinitely (until the machine is reset or until I manually terminate it)?