702-100 Exam Dumps : Linux Professional Institute BSD Specialist

The cron job syntax consists of five fields that specify the time and date of execution, followed by the command or script to run. The fields are: minute, hour, day of month, month, and day of week. Each field can have a specific value, a range, a list, a wildcard (), or a step value. The wildcard () means any possible value for that field. The option B sets the minute field to 0 and the hour field to *, which means the script will run at the 0th minute of every hour, regardless of the day, month, or weekday. This is equivalent to once per hour. The other options are either invalid syntax or do not match the desired frequency. For example, option A sets all fields to *, which means the script will run every minute of every hour of every day, month, and weekday. Option C sets the minute field to * and the hour field to 0, which means the script will run every minute of the 0th hour, or once per day at midnight. Option D has a typo (o instead of *) and option E sets the day of month field to o, which is not a valid value. References:

• crontab - FreeBSD crontab(5) Manual Page1
• Crontab Explained in Linux [With Examples] - Linux Handbook2

The pgrep command is used to find processes by various criteria, such as user name, group name, process ID, command name, etc. The -u option specifies the user name or user ID to match. Therefore, the command pgrep -u bob will show all processes owned by the user bob. The output will be a list of process IDs, one per line. To show more information about the processes, such as command name, arguments, state, etc., the -l, -a, and -f options can be used. For example, the command pgrep -l -u bob will show the process ID and the command name for each process owned by bob. References:

• pgrep - FreeBSD, the manual page for the pgrep command on FreeBSD.
• How to use pgrep and pkill commands in Linux - Linuxize, a tutorial on how to use the pgrep and pkill commands in Linux.

The -e option of the crontab command opens the current user’s crontab in an editor. The editor used is determined by the environment variables VISUAL or EDITOR. If neither of these variables is set, the default editor is vi. The user can edit the crontab file to add, modify, or delete cron jobs, which are scheduled commands or scripts that run at a specified time or interval. The crontab file has the following format:

minute hour day-of-month month day-of-week command

Each field can be a number, a range, a list, or an asterisk (*), which means all possible values. The command can be any valid shell command or script. For example, the following crontab entry runs the backup.sh script every day at 2:30 AM:

30 2 * * * /home/user/backup.sh

To save and install the crontab file, the user needs to exit the editor. The crontab command will check the syntax of the file and report any errors. If the file is valid, it will be installed and the cron daemon will execute the cron jobs according to the schedule. References:

• crontab(1) - Linux manual page
• FreeBSD Handbook: 11.6. Scheduling Tasks