notebook/notes/posix/signals.md

title	TARGET DECK	FILE TAGS	tags
Signals	Obsidian::STEM	posix::signal	posix signal

Overview

This is an overview of specific POSIX signals.

Code	Name
1	SIGHUP
2	SIGINT
4	SIGILL
6	SIGABRT
7	SIGBUS
8	SIGFPE
9	SIGKILL
11	SIGSEGV
13	SIGPIPE
15	SIGTERM

Details

%%ANKI Basic What command can we run to access the official manual page for signals? Back: man 7 signal Reference: Dowling, “A List of Signals and What They Mean.” Tags: linux::cli

END%%

%%ANKI Basic What command can we run to print POSIX signals to the terminal? Back: kill -l Reference: Cooper, Mendel. “Advanced Bash-Scripting Guide,” n.d., 916.

END%%

%%ANKI Cloze {ascii} is to ASCII as {kill -l} is to POSIX signals. Reference: Cooper, Mendel. “Advanced Bash-Scripting Guide,” n.d., 916.

END%%

SIGHUP (1)

A process receives a SIGHUP signal when the terminal it is attached to goes away before it finishes executing.

%%ANKI Cloze Signal {SIGHUP} corresponds to number {1}. Reference: Dowling, “A List of Signals and What They Mean.”

END%%

%%ANKI Basic What is the HUP in SIGHUP an acronym for? Back: Hang up Reference: Dowling, “A List of Signals and What They Mean.”

END%%

%%ANKI Basic When does a process receive a SIGHUP signal? Back: When the terminal it is attached to disappears before it finishes execution. Reference: Dowling, “A List of Signals and What They Mean.”

END%%

%%ANKI Basic What historical context led to SIGHUP's name? Back: This name refers to hanging up the telephone in the days of telephone modems. Reference: Dowling, “A List of Signals and What They Mean.”

END%%

%%ANKI Basic What command is used to make a program immune to SIGHUP signals? Back: nohup Reference: man 1 nohup Tags: linux::cli

END%%

%%ANKI Basic If a nohup program's stdin is a terminal, where is its input redirected from? Back: An unreadable file. Reference: man 1 nohup Tags: linux::cli

END%%

%%ANKI Basic If a nohup program's stdout is a terminal, where is its output redirected to? Back: nohup.out if possible, $HOME/nohup.out otherwise. Reference: man 1 nohup Tags: linux::cli

END%%

%%ANKI Basic If a nohup program's stderr is a terminal, where is its errors redirected to? Back: stdout Reference: man 1 nohup Tags: linux::cli

END%%

%%ANKI Basic What command can be run to view all processes that would receive a SIGHUP when the current terminal exits? Back: ps T Reference: man 1 ps

END%%

SIGINT (2)

Indicates the process was interrupted by the user. Happens when pressing Ctrl-C from the controlling terminal.

%%ANKI Cloze Signal {SIGINT} corresponds to number {2}. Reference: Dowling, “A List of Signals and What They Mean.”

END%%

%%ANKI Basic What control sequence usually triggers a SIGINT? Back: Ctrl-C Reference: Dowling, “A List of Signals and What They Mean.”

END%%

%%ANKI Basic What is the INT in SIGINT short for? Back: Interrupt Reference: Dowling, “A List of Signals and What They Mean.”

END%%

References

• Cooper, Mendel. “Advanced Bash-Scripting Guide,” n.d., 916.
• Dowling, “A List of Signals and What They Mean.”