Due to low disk space, a Linux administrator finding and removing all log files that were modified more than 180 days ago. Which of the following commands will accomplish this task?

Correct Answer:C
The command that will accomplish the task of finding and removing all log files that were modified more than 180 days ago is find /var/log -type f -mtime +180 -exec rm {} ;. This command will use find to search for files (-type f) under /var/log directory that have a modification time (-mtime) older than 180 days (+180). For each matching file, it will execute (-exec) the rm command to delete it, passing the file name as an argument ({}). The command will end with a semicolon (;), which is escaped with a backslash to prevent shell interpretation.
The other options are not correct commands for accomplishing the task. The find /var/log - type d -mtime +180 -print -exec rm {} ; command will search for directories (-type d) instead of files, and print their names (-print) before deleting them. This is not what the task requires. The find /var/log -type f -modified +180 -rm command is invalid because there is no such option as -modified or -rm for find. The correct options are -mtime and -delete, respectively. The find /var/log -type c -atime +180 –remove command is also invalid because there is no such option as –remove for find. Moreover, it will search for character special files (-type c) instead of regular files, and use access time (-atime) instead of modification time. References: find(1) - Linux manual page; Find and delete files older than n days in Linux

A systems administrator requires that all files that are created by the user named web have read-only permissions by the owner. Which of the following commands will satisfy this requirement?

Correct Answer:C
The command that will satisfy the requirement of having all files that are created by the user named web have read-only permissions by the owner is echo “umask 377” >> /home/web/.bashrc. This command will append the umask 377 command to the end of the .bashrc file in the web user’s home directory. The .bashrc file is a shell script that is executed whenever a new interactive shell session is started by the user. The umask command sets the file mode creation mask, which determines the default permissions for newly created files or directories by subtracting from the maximum permissions (666 for files and 777 for directories). The umask 377 command means that the user does not want to give any permissions to the group or others (3 = 000 in binary), and only wants to give read permission to the owner (7 - 3 = 4 = 100 in binary). Therefore, any new file created by the web user will have read-only permission by the owner (400) and no permission for anyone else. References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 8: Managing Users and Groups; Umask Command in Linux | Linuxize

A Linux engineer needs to create a custom script, cleanup.sh, to run at boot as part of the system services. Which of the following processes would accomplish this task?

Correct Answer:C
The process that will accomplish the task of creating a custom script to run at boot as part of the system services is:
✑ Create a unit file in the /etc/systemd/system/ directory. A unit file is a configuration
file that defines the properties and behavior of a systemd service. The systemd is a system and service manager that controls the startup and operation of Linux systems. The /etc/systemd/system/ directory is the location where the administrator can create and store custom unit files. The unit file should have a name that matches the name of the script, such as cleanup.service, and should contain the following sections and options:
✑ Run the command systemct1 enable cleanup. This command will enable the service and create the necessary symbolic links to start the service at boot.
✑ Run the command systemct1 is-enabled cleanup. This command will check the status of the service and confirm that it is enabled.
This process will create a custom script, cleanup.sh, to run at boot as part of the system services. This is the correct process to use to accomplish the task. The other options are incorrect because they either use the wrong directory for the unit file (/etc/default/, /etc/skel/, or /etc/sysctl.d/) or do not create a unit file at
all. References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 15: Managing System Services, pages 457-459.

A Linux user is trying to execute commands with sudo but is receiving the following error:
$ sudo visudo
>>> /etc/sudoers: syntax error near line 28 <<< sudo># grep root /etc/shadow root :* LOCK *: 14600 ::::::
Which of the following actions will resolve this issue?

Correct Answer:B

A Linux administrator was tasked with deleting all files and directories with names that are contained in the sobelete.txt file. Which of the following commands will accomplish this task?

Correct Answer:D
The command cat toDelete.txt | xargs rm -rf will delete all files and directories with names that are contained in the toDelete.txt file. The cat command reads the file and outputs its contents to the standard output. The | operator pipes the output to the next command. The xargs command converts the output into arguments for the next command. The rm -rf command removes the files and directories recursively and forcefully. This is the correct way to accomplish the task. The other options are incorrect because they either use the wrong options (-f instead of -a for xargs), the wrong arguments (toDelete.txt instead of toDelete.txt filename for rm), or the wrong commands (rm instead of xargs). References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 11: Managing Files and Directories, pages 349-350.

A systems engineer is adding a new 1GB XFS filesystem that should be temporarily mounted under /ops/app. Which of the following is the correct list of commands to achieve this goal?

Correct Answer:D
The list of commands in option D is the correct way to achieve the goal. The commands are as follows:
✑ fallocate -l 1G /ops/app.img creates a 1GB file named app.img under the /ops directory.
✑ mkfs.xfs /ops/app.img formats the file as an XFS filesystem.
✑ mount -o loop /ops/app.img /ops/app mounts the file as a loop device under the /ops/app directory. The other options are incorrect because they either use the wrong commands (dd or truncate instead of fallocate), the wrong options (-t or - f instead of -o), or the wrong order of arguments (/ops/app.img /ops/app instead of /ops/app /ops/app.img). References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 10: Managing Storage, pages 323-324.