Scripting and Task Scheduling Flashcards

Which shebang line is correct for a bash script on RHEL?

Answer: #!/bin/bash

`#!/bin/bash` is the correct shebang that tells the kernel to use `/bin/bash` as the interpreter for the script.

What does the `$?` variable represent in a bash script?

Answer: Exit code of the last command

`$?` holds the exit status of the most recently executed foreground command (0 = success, non-zero = failure).

Which `cron` field position represents 'day of the week'?

Answer: 5th field

In cron syntax, the fields are: minute, hour, day-of-month, month, day-of-week — making day-of-week the 5th field.

What command lists all cron jobs for the current user?

Answer: crontab -l

`crontab -l` lists (displays) the current user's crontab without editing it.

Which special cron string runs a job every day at midnight?

Answer: All of the above

`@midnight`, `@daily`, and `0 0 * * *` are all valid cron expressions that schedule a job to run at midnight every day.

What is the purpose of `systemd.timer` units in RHEL?

Answer: Schedule tasks as a modern cron replacement using systemd

Systemd timer units provide a modern alternative to cron for scheduling tasks, with better integration into systemd logging and dependency management.