Linux Signal Reference

Hangup. Terminal closed or controlling process died. Often used to reload configuration.

Interrupt from keyboard (Ctrl+C). Requests graceful termination.

Quit from keyboard (Ctrl+\). Like SIGINT but produces a core dump.

Illegal instruction. Process attempted to execute an invalid CPU instruction.

Trace/breakpoint trap. Used by debuggers.

Abort. Sent by abort() call when a fatal error is detected.

Bus error — invalid memory address alignment.

Floating point / arithmetic exception (e.g. division by zero).

Kill. Force-terminates the process immediately. Cannot be caught or ignored.

User-defined signal 1. Application-specific meaning.

Segmentation fault — invalid memory reference.

User-defined signal 2. Application-specific meaning.

Broken pipe — write to pipe with no reader.

Alarm clock. Sent when timer set by alarm() or setitimer() expires.

Termination. Default kill signal. Requests graceful shutdown.

Child stopped or terminated. Sent to parent when child process state changes.

Continue. Resume a stopped process.

Stop process. Cannot be caught or ignored. Like Ctrl+Z but programmatic.

Terminal stop (Ctrl+Z). Unlike SIGSTOP, this can be caught.

Terminal input for background process — stops reading.

Terminal output for background process — stops writing.

Urgent condition on socket — out-of-band data available.

CPU time limit exceeded (set with ulimit -t).

File size limit exceeded (set with ulimit -f).

Terminal window size changed. Used by ncurses apps to redraw.

I/O now possible on a file descriptor.

Bad system call. Process made an invalid syscall.