A scannable reference for every standard POSIX/Linux process signal — SIGHUP through SIGSYS — showing each signal’s number, its default action (Term, Core, Ign, Stop, Cont), whether it can be caught, what raises it and the matching shell exit code (128+N). In your browser, free.

Every standard POSIX/Linux process signal, explained. Everything runs in your browser from a built-in reference — nothing is sent to the server.

Signal No. Default action Catchable Description Exit code
No signal matches your search.
Try a different name or number — for example SIGTERM, 11 or segmentation.
In addition to these, Linux provides real-time signals SIGRTMIN to SIGRTMAX (typically signals 34–64). They have no predefined meaning and are delivered in guaranteed order — applications assign their own purpose to them.
Signal numbers shown are the defaults for the x86/ARM ABI. A few signals carry different numbers on other architectures (for example Alpha, MIPS and SPARC), so always prefer the symbolic name (SIGKILL) over the raw number (9) in scripts.

About Linux Signals

The Linux Signals reference lists every standard POSIX/Linux process signal, from SIGHUP through SIGSYS, in one scannable table. Each row shows the signal’s number, its default action — Terminate, Core dump, Ignore, Stop or Continue — whether a process can catch it, what typically raises it, and the shell exit code (128 + N) you see when a process dies from it.

That exit-code column closes the loop developers hit daily: a container that exits with 137 was killed by SIGKILL (9), a crash with 139 was a segmentation fault from SIGSEGV (11), and a clean shutdown at 143 came from SIGTERM (15). Search works by name, number, exit code or meaning, so you can start from whichever clue you have.

Two footnotes cover the parts references usually skip: the real-time signals SIGRTMIN through SIGRTMAX, which have no predefined meaning and are delivered in guaranteed order, and the architecture caveat — a few signal numbers differ on Alpha, MIPS and SPARC, which is why scripts should use symbolic names. Everything runs in your browser.

How to use Linux Signals

  1. Search for a signal by name (SIGKILL), number (9), shell exit code (137) or a keyword like “segmentation”.
  2. Read the row: number, default action, whether it can be caught, and what raises it.
  3. Use the exit-code column to translate a 128+N shell status back to the signal that killed the process.
  4. Copy the signal name or exit code with the row’s copy buttons.
  5. Check the notes on real-time signals and per-architecture numbering if you are writing portable scripts.

Frequently asked questions

SIGTERM (15) politely asks a process to exit — it can be caught, so the process may clean up first. SIGKILL (9) terminates immediately at the kernel level and cannot be caught, blocked or ignored. Always try SIGTERM before resorting to kill -9.

SIGKILL and SIGSTOP. The kernel enforces both directly, so no handler can intercept them — SIGKILL always terminates the process and SIGSTOP always suspends it.

When a process is killed by a signal, the shell reports 128 plus the signal number. So 139 is 128 + 11: the process died from SIGSEGV, a segmentation fault. The table lists this exit code next to every fatal signal.

SIGRTMIN through SIGRTMAX — typically numbers 34 to 64 on Linux. Unlike standard signals they carry no predefined meaning and are queued and delivered in guaranteed order, so applications assign their own purposes to them.

Because a few signal numbers differ between CPU architectures such as Alpha, MIPS and SPARC. The symbolic name — kill -TERM rather than kill -15 — means the same thing everywhere, so it is the portable choice.

Yes, completely free. The full table is built into the page and all searching and copying happens in your browser.

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