Linux signals: Difference between revisions
From Leo's Notes
This page was last edited on 24 September 2022, at 09:03.
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Signals are messages that are sent to a program. | |||
Here are some Linux signals in brief detail. You may quickly list available signals by running <code>kill -l</code>. | |||
{| class="wikitable" | {| class="wikitable" | ||
!Signal Name | !Signal Name | ||
| Line 10: | Line 13: | ||
|SIGINT | |SIGINT | ||
|2 | |2 | ||
|Signals when the Linux user presses | |Signals when the Linux user presses <code>Ctrl-c</code> | ||
|- | |- | ||
|SIGQUIT | |SIGQUIT | ||
|3 | |3 | ||
|Signals when the Linux user presses | |Signals when the Linux user presses <code>Ctrl-d</code> | ||
|- | |- | ||
|SIGILL | |SIGILL | ||
| Line 22: | Line 25: | ||
|SIGTRAP | |SIGTRAP | ||
|5 | |5 | ||
| | |Trap or breakpoint signal | ||
|- | |- | ||
|SIGABRT | |SIGABRT | ||
|6 | |6 | ||
| | |Abort signal | ||
|- | |- | ||
|SIGBUS | |SIGBUS | ||
|7 | |7 | ||
| | |Illegal access to an undefined portion of memory | ||
|- | |- | ||
|SIGFPE | |SIGFPE | ||
| Line 42: | Line 45: | ||
|SIGUSR1 | |SIGUSR1 | ||
|10 | |10 | ||
| | |User defined signal. Typically programs will print its status (eg. <code>dd</code>) | ||
|- | |- | ||
|SIGSEGV | |SIGSEGV | ||
| Line 50: | Line 53: | ||
|SIGUSR2 | |SIGUSR2 | ||
|12 | |12 | ||
| | |User defined signal. | ||
|- | |- | ||
|SIGPIPE | |SIGPIPE | ||
|13 | |13 | ||
| | |Write on a pipe with no one to read it | ||
|- | |- | ||
|SIGALRM | |SIGALRM | ||
| Line 66: | Line 69: | ||
|SIGSTKFLT | |SIGSTKFLT | ||
|16 | |16 | ||
| | |Stack fault | ||
|- | |- | ||
|SIGSTOP | |SIGSTOP | ||
| Line 74: | Line 77: | ||
|SIGCONT | |SIGCONT | ||
|18 | |18 | ||
| | |Resume program execution from a <code>SIGSTOP</code> or <code>SIGTSTP</code>. | ||
|- | |- | ||
|SIGSTOP | |SIGSTOP | ||
|19 | |19 | ||
| | |Stop signal sent with <code>kill -STOP</code> to suspend a program. Cannot be ignored by the program. | ||
|- | |- | ||
|SIGTSTP | |SIGTSTP | ||
|20 | |20 | ||
| | |Signals when the Linux user presses <code>Ctrl-z</code>. May be ignored by the program. | ||
|- | |- | ||
|SIGTTIN | |SIGTTIN | ||
|21 | |21 | ||
| | |Delivered to a background process if it tries to read from the terminal. | ||
|- | |- | ||
|SIGTTOU | |SIGTTOU | ||
|22 | |22 | ||
| | |Delivered to a background process if it tries to write to the terminal. | ||
|- | |- | ||
|SIGURG | |SIGURG | ||
|23 | |23 | ||
| | |Urgent data received on a socket. | ||
|- | |- | ||
|SIGXCPU | |SIGXCPU | ||
|24 | |24 | ||
| | |Process exceeds CPU limit or time. Save your work before you get killed. | ||
|- | |- | ||
|SIGXFSZ | |SIGXFSZ | ||
|25 | |25 | ||
| | |File written by this process exceeded some size limit. | ||
|- | |- | ||
|SIGVTALRM | |SIGVTALRM | ||
|26 | |26 | ||
| | |CPU time elapsed | ||
|- | |- | ||
|SIGPROF | |SIGPROF | ||
| Line 114: | Line 117: | ||
|SIGWINCH | |SIGWINCH | ||
|28 | |28 | ||
| | |Window size changed. | ||
|- | |- | ||
|SIGIO | |SIGIO | ||
|29 | |29 | ||
| | |Signal input/output trap. Program should abort unless handled properly. | ||
|- | |- | ||
|SIGPWR | |SIGPWR | ||
|30 | |30 | ||
| | |Power failure? | ||
|- | |- | ||
|SIGSYS | |SIGSYS | ||
|31 | |31 | ||
| | |Bad system call | ||
|} | |} | ||
== See also == | |||
* Wikipedia's article outlines all the signals and their default actions: https://en.wikipedia.org/wiki/Signal_(IPC) | |||
Latest revision as of 09:03, 24 September 2022
Signals are messages that are sent to a program.
Here are some Linux signals in brief detail. You may quickly list available signals by running kill -l.
| Signal Name | Signal Number | Description |
|---|---|---|
| SIGHUP | 1 | Hangs up signals when controlling the terminal or at the end of the controlling processes. |
| SIGINT | 2 | Signals when the Linux user presses Ctrl-c
|
| SIGQUIT | 3 | Signals when the Linux user presses Ctrl-d
|
| SIGILL | 4 | Illegal instruction trap |
| SIGTRAP | 5 | Trap or breakpoint signal |
| SIGABRT | 6 | Abort signal |
| SIGBUS | 7 | Illegal access to an undefined portion of memory |
| SIGFPE | 8 | Signals when any unexpected mathematical operation is performed. |
| SIGKILL | 9 | When any of the process issues this signal, it will quit immediately. |
| SIGUSR1 | 10 | User defined signal. Typically programs will print its status (eg. dd)
|
| SIGSEGV | 11 | Segmentation fault |
| SIGUSR2 | 12 | User defined signal. |
| SIGPIPE | 13 | Write on a pipe with no one to read it |
| SIGALRM | 14 | Signals for alarm clock |
| SIGTERM | 15 | Signals to terminate the process or the software. |
| SIGSTKFLT | 16 | Stack fault |
| SIGSTOP | 17 | Signals to stop the process in Linux. |
| SIGCONT | 18 | Resume program execution from a SIGSTOP or SIGTSTP.
|
| SIGSTOP | 19 | Stop signal sent with kill -STOP to suspend a program. Cannot be ignored by the program.
|
| SIGTSTP | 20 | Signals when the Linux user presses Ctrl-z. May be ignored by the program.
|
| SIGTTIN | 21 | Delivered to a background process if it tries to read from the terminal. |
| SIGTTOU | 22 | Delivered to a background process if it tries to write to the terminal. |
| SIGURG | 23 | Urgent data received on a socket. |
| SIGXCPU | 24 | Process exceeds CPU limit or time. Save your work before you get killed. |
| SIGXFSZ | 25 | File written by this process exceeded some size limit. |
| SIGVTALRM | 26 | CPU time elapsed |
| SIGPROF | 27 | |
| SIGWINCH | 28 | Window size changed. |
| SIGIO | 29 | Signal input/output trap. Program should abort unless handled properly. |
| SIGPWR | 30 | Power failure? |
| SIGSYS | 31 | Bad system call |
See also
- Wikipedia's article outlines all the signals and their default actions: https://en.wikipedia.org/wiki/Signal_(IPC)