Process

Table of Contents Process Log Start Kill Inter-process communication (IPC) Signals Basics List

Process

Log

Log process calls

• A version
• Another

Start

Background/Foreground:

• start process in background <COMMAND> &
• bring process in foreground fg <PROCESS_ID>

Detach from shell

nohup $COMMAND . &>/dev/null &

Ignore signals:

• make a process ignore SIGHUP signal nohup <COMMAND>
• make a process ignore SIGHUP signal, and allow logout (redirect input to NULL, output and error to separate files) nohup <COMMAND> > <OUTPUT_FILE> 2> <ERROR_FILE> < /dev/null
• make a process ignore SIGHUP signal, and allow logout (redirect input, output, error to NULL) nohup <COMMAND> >/dev/null 2>&1

$PROGRAM </dev/null &>/dev/null &

https://superuser.com/questions/178587/how-do-i-detach-a-process-from-terminal-entirely

Kill

List:

• force, using process ID kill -9 <PID
• using process name: pkill '<PROCESS_NAME'
• interactive mode (fabulous kill): fkill install

Inter-process communication (IPC)

Signals

Basics

A signal is an asynchronous notification sent to a process or to a specific thread within the same process to notify it of an event. If the process has previously registered a signal handler, that routine is executed. Otherwise, the default signal handler is executed. Signals are similar to interrupts, the difference being that

• interrupts are mediated by the processor and handled by the kernel
• signals are mediated by the kernel (possibly via system calls) and handled by processes

WP

List

List:

• Triggered by / Name / Code
• a user wishes to interrupt the process (Ctrl-C) / INTerruption / SIGINT
• ? wishes to terminate the process (Ctrl-C) / TERmination / SIGTERM (SIGINT is nearly identical to SIGTERM)
• terminate immediately / KILL the process / SIGKILL (cannot be caught or ignored)

1. 1. Run parallel

https://linuxsimply.com/bash-scripting-tutorial/basics/executing/run-commands-in-parallel/

Wait for all processes to finish

sleep 5 & sleep 1 & wait