0x05. Processes and signals Tasks 0. What is my PID Write a Bash script that displays its own PID.
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List your processes Write a Bash script that displays a list of currently running processes. Requirements: Must show all processes, for all users, including those which might not have a TTY Display in a user-oriented format Show process hierarchy
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Show your Bash PID Using your previous exercise command, write a Bash script that displays lines containing the bash word, thus allowing you to easily get the PID of your Bash process. Requirements: You cannot use pgrep The third line of your script must be # shellcheck disable=SC2009 (for more info about ignoring shellcheck error here)
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Show your Bash PID made easy Write a Bash script that displays the PID, along with the process name, of processes whose name contain the word bash. Requirements: You cannot use ps
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To infinity and beyond Write a Bash script that displays To infinity and beyond indefinitely. Requirements: In between each iteration of the loop, add a sleep 2
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Don't stop me now! We stopped our 4-to_infinity_and_beyond process using ctrl+c in the previous task, there is actually another way to do this. Write a Bash script that stops 4-to_infinity_and_beyond process. Requirements: You must use kill Terminal #0
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Stop me if you can Write a Bash script that stops 4-to_infinity_and_beyond process. Requirements: You cannot use kill or killall Terminal #0
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Highlander Write a Bash script that displays: To infinity and beyond indefinitely With a sleep 2 in between each iteration I am invincible!!! when receiving a SIGTERM signal Make a copy of your 6-stop_me_if_you_can script, name it 67-stop_me_if_you_can, that kills the 7-highlander process instead of the 4-to_infinity_and_beyond one.
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Beheaded process Write a Bash script that kills the process 7-highlander. I started 7-highlander in Terminal #0 and then run 8-beheaded_process in terminal #1 and we can see that the 7-highlander has been killed.
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Process and PID file Write a Bash script that: Creates the file /var/run/myscript.pid containing its PID Displays To infinity and beyond indefinitely Displays I hate the kill command when receiving a SIGTERM signal Displays Y U no love me?! when receiving a SIGINT signal Deletes the file /var/run/myscript.pid and terminates itself when receiving a SIGQUIT or SIGTERM signal Executing the 100-process_and_pid_file script and killing it with ctrl+c.
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Manage my process Programs that are detached from the terminal and running in the background are called daemons or processes, need to be managed. The general minimum set of instructions is: start, restart and stop. The most popular way of doing so on Unix system is to use the init scripts.
Write a manage_my_process Bash script that: Indefinitely writes I am alive! to the file /tmp/my_process In between every I am alive! message, the program should pause for 2 seconds Write Bash (init) script 101-manage_my_process that manages manage_my_process. (both files need to be pushed to git) Requirements: When passing the argument start: Starts manage_my_process Creates a file containing its PID in /var/run/my_process.pid Displays manage_my_process started When passing the argument stop: Stops manage_my_process Deletes the file /var/run/my_process.pid Displays manage_my_process stopped When passing the argument restart Stops manage_my_process Deletes the file /var/run/my_process.pid Starts manage_my_process Creates a file containing its PID in /var/run/my_process.pid Displays manage_my_process restarted Displays Usage: manage_my_process {start|stop|restart} if any other argument or no argument is passed Note that this init script is far from being perfect (but good enough for the sake of manipulating process and PID file), for example we do not handle the case where we check if a process is already running when doing ./101-manage_my_process start, in our case it will simply create a new process instead of saying that it is already started.
- Zombie Write a C program that creates 5 zombie processes. Requirements: For every zombie process created, it displays Zombie process created, PID: ZOMBIE_PID Your code should use the Betty style. It will be checked using betty-style.pl and betty-doc.pl When your code is done creating the parent process and the zombies, use the function bellow
In Terminal #0, I start by compiling 102-zombie.c and executing zombie which creates 5 zombie processes. In Terminal #1, I display the list of processes and look for lines containing Z+.* which catches zombie process.