Process and PID file

Author: AbrahamAlgorithm

0x05-processes_and_signals/0-what-is-my-pid

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+#!/usr/bin/env bash
+# print the pud of this script
+echo "$$"

0x05-processes_and_signals/1-list_your_processes

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+#!/usr/bin/env bash
+# print all processes for all users and TTY displayed
+ps -auxf

0x05-processes_and_signals/100-process_and_pid_file

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+#!/usr/bin/env bash
+# Task 9
+terminator () {
+    rm /var/run/myscript.pid
+    exit
+}
+echo "$$" > /var/run/myscript.pid
+while true
+do
+  echo "To infinity and beyond"
+  sleep 2
+  trap 'echo "Y U no love me?"' SIGINT
+  trap 'echo "I hate the kill command"; terminator' SIGTERM
+  trap 'terminator' SIGQUIT
+done

0x05-processes_and_signals/101-manage_my_process

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+#!/usr/bin/env bash
+# Manages the script manage_my_process.
+#   When passed the argument `start`:
+#     1. Starts manage_my_process
+#     2. Creates a file containings its PID in /var/run/my_process.pid
+#     3. Displays "manage_my_process started"
+#   When passed the argument `stop`:
+#     1. Stops manage_my_process
+#     2. Deletes the file /var/run/my_process.pid
+#     3. Displays "manage_my_process stopped"
+#   When passed the argument `restart`:
+#     1. Stops manage_my_process
+#     2. Deletes the file /var/run/my_process.pid
+#     3. Starts manage_my_process
+#     4. Creates a file containing its PID in /var/run/my_process.pid
+#     5. Displays "manage_my_process restarted"
+#   If any other or no arguments are passed, displays
+#+  "Usage: manage_my_process {start|stop|restart}"
+
+if [ "$1" == "start" ]
+then
+  ./manage_my_process &
+  echo $$ > /var/run/my_process.pid
+  echo "manage_my_process started"
+
+elif [ "$1" == "stop" ]
+then
+  kill "$(pgrep -f /manage_my_process)" 
+  rm /var/run/my_process.pid
+  echo "manage_my_process stopped"
+
+elif [ "$1" == "restart" ]
+then
+  kill "$(pgrep -f /manage_my_process)"
+  rm /var/run/my_process.pid
+  ./manage_my_process &
+  echo $$ > /var/run/my_process.pid
+  echo "manage_my_process restarted"
+
+else
+  echo "Usage: manage_my_process {start|stop|restart}"
+fi

0x05-processes_and_signals/102-zombie.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+/**
+ * infinite_while - Run an infinite while loop.
+ *
+ * Return: Always 0.
+ */
+int infinite_while(void)
+{
+	while (1)
+	{
+		sleep(1);
+	}
+	return (0);
+}
+
+/**
+ * main - Creates five zombie processes.
+ *
+ * Return: Always 0.
+ */
+int main(void)
+{
+	pid_t pid;
+	char count = 0;
+
+	while (count < 5)
+	{
+		pid = fork();
+		if (pid > 0)
+		{
+			printf("Zombie process created, PID: %d\n", pid);
+			sleep(1);
+			count++;
+		}
+		else
+			exit(0);
+	}
+
+	infinite_while();
+
+	return (EXIT_SUCCESS);
+}

0x05-processes_and_signals/2-show_your_bash_pid

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+#!/usr/bin/env bash
+# Display the list of pid of current running processes
+# shellcheck disable=SC2009
+ps -aux | grep bash

0x05-processes_and_signals/3-show_your_bash_pid_made_easy

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+#!/usr/bin/env bash
+# Display the process with their name and id (bash)
+pgrep bash -l

0x05-processes_and_signals/4-to_infinity_and_beyond

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+#!/usr/bin/env bash
+# print to infinity and beyond infinitely
+i=0
+while [ $i -eq 0 ]
+do
+  echo "To infinity and beyond"
+  sleep 2
+done

0x05-processes_and_signals/5-dont_stop_me_now

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+#!/usr/bin/env bash
+# termiante a running while loop
+kill "$(pgrep -f 4-to_infinity_and_beyond)"

0x05-processes_and_signals/6-stop_me_if_you_can

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+#!/usr/bin/env bash
+# stop while loop without kill and killall
+pkill -f "4-to_infinity_and_beyond"

0x05-processes_and_signals/67-stop_me_if_you_can

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+#!/usr/bin/env bash
+# stop while loop without kill and killall
+pkill -f "7-highlander"

0x05-processes_and_signals/7-highlander

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+#!/usr/bin/env bash
+# print to infinity and beyond infinitely
+i=0
+while [ $i -eq 0 ]
+do
+  echo "To infinity and beyond"
+  sleep 2
+  trap 'echo "I am invincible!!!"' 15
+done

0x05-processes_and_signals/8-beheaded_process

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+#!/usr/bin/env bash
+# kill the highlander
+pkill -f -SIGKILL "7-highlander"

0x05-processes_and_signals/README.md

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+Linux, processes, siganls and management

0x05-processes_and_signals/a

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+#!/usr/bin/env bash
+# Indefinitely writes "I am alive" to the file /tmp/my_process.
+#   Pauses two seconds in between each message.
+
+while true
+do
+  echo "I am alive!" >> "/tmp/my_process"
+  sleep 2
+done