Questions tagged [signals]
A signal is a message which can be sent to a running process. Signals can be initiated by programs, users, or administrators.
634 questions
3 votes
2 answers
117 views
How can restart_syscall restart syscalls that are not restartable?
Let's read man 2 restart_syscall: restart_syscall() is used for restarting only those system calls that, when restarted, should adjust their time-related parameters—namely poll(2) (since Linux 2.6.24)...
- 203
4 votes
0 answers
229 views
Confused about SIGINT trap
I am confused about the processing of SIGINT and EXIT traps in Bash scripts. I wrote this script to test: #!/usr/bin/env bash set -e exit_trap() { printf "In exit_trap \$?=$?\n" exit 0 ...
- 2,380
4 votes
1 answer
244 views
Why SIGTSTP (^Z/Ctrl-Z/suspend) doesn't work when process blocked redirecting write into a FIFO/pipe not open for reading yet? And what to do then?
Sometimes, a command is stalled attempting to write to a FIFO/pipe that no other process is currently reading from, but typing Ctrl-Z to put the process to the background by sending it the SIGTSTP ...
- 454
2 votes
1 answer
98 views
Detectng missed SIGWINCH in Bash extension, when apparent terminal size has not changed
I maintain an extension for the Bash environment called Basta. Basta provides a scroll-protected status line at the bottom of your ANSI/VT100 terminal. When Basta sets itself up, the effective number ...
- 8,897
2 votes
1 answer
309 views
Why does the SIGCHLD generated by process continuation not activate the trap?
I am using linux (Ubuntu) and bash. I made a simple Go program. Literally infinite for-loop that prints text every 20 seconds. package main import ( "fmt" "time" ) func ...
- 517
1 vote
2 answers
154 views
Why does the kill command not work for SIGTSTP, but works for some other signals (SIGSTOP/SIGINT etc.)?
I have the following two simple programs. Parent: package main import ( "fmt" "syscall" ) func main() { attr := &syscall.ProcAttr{ Files: []uintptr{0, 1, ...
- 517
0 votes
0 answers
60 views
Why does sudo change process session id using setsid()?
I've been writing a script that spawns a child process as a different user via sudo then I realized that my script is not getting SIGINT as opposed to when I run it without sudo. As suspected strace ...
- 101
1 vote
2 answers
101 views
Failed to core dump with send_sig(task, SIGSEGV, 1) from Linux kernel
I am working in an embedded Linux system, and now I want to trigger a core dump from within kernel by using send_sig(task, SIGSEGV, 1). There is a process A having 10 threads, occasionally, there is a ...
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