EX200 Essential Tools Practice Test 5 — 15 Questions

Question 1

Which TWO commands can be used to view the contents of a compressed file named 'data.log.gz' without decompressing it permanently? (Choose exactly two.)

Accepted Answer

zcat data.log.gz. B is correct because `zcat` reads the contents of a gzip-compressed file and outputs them to standard output without permanently decompressing the file. It is functionally equivalent to `gunzip -c` and is the standard tool for viewing compressed text files in place.

Answer

gunzip data.log.gz

Answer

gzip -d data.log.gz

Answer

bzcat data.log.gz

Question 2

Which THREE of the following are valid methods to schedule a recurring task in Red Hat Enterprise Linux 8? (Choose exactly three.)

Accepted Answer

Creating a systemd timer unit. Systemd timer units are the modern, recommended method for scheduling recurring tasks in RHEL 8. They replace traditional cron-based scheduling by leveraging systemd's service and timer units, providing features like monotonic timers, calendar events, and integration with systemd's logging and dependency management.

Answer

Using the 'batch' command

Answer

Using the 'at' command

Question 3

Which TWO of the following are valid examples of using redirection and pipes in bash to append the output of a command to a file while also displaying it on the terminal? (Choose exactly two.)

Accepted Answer

command | tee -a file. `tee -a file` reads from stdin and writes both to stdout and appends to the named file. The pipe `|` sends the stdout of `command` to `tee`, so the output is displayed on the terminal and appended to `file`. The `-a` flag ensures append mode, not overwrite.

Answer

command 2>&1 | tee file

Answer

command > file

Answer

command >> file

Question 4

A system administrator has created a new group named 'ops'. The administrator wants to add the existing user 'alice' to this group as a supplementary group without affecting her current group memberships. Which command should be used?

Accepted Answer

usermod -aG ops alice. The `-a` (append) flag combined with `-G` (supplementary groups) in `usermod` adds the user 'alice' to the 'ops' group without removing her from any existing supplementary groups. Without `-a`, the `-G` flag alone would replace the user's current supplementary group list with only the specified groups, which would remove her from any other groups she already belongs to.

Answer

usermod -G ops alice

Answer

groupadd ops alice

Answer

usermod -g ops alice

Question 5

A system is experiencing high CPU usage. The administrator suspects a process is stuck in an infinite loop. Which command can be used to identify the most CPU-intensive process in real-time?

Accepted Answer

top. The `top` command provides a real-time, dynamic view of system processes, sorted by CPU usage by default. It continuously refreshes, making it ideal for identifying the most CPU-intensive process as it runs, which directly addresses the scenario of a suspected infinite loop causing high CPU usage.

Answer

lsof

Answer

ps aux

Answer

strace

Question 6

An administrator needs to schedule a script to run every Monday, Wednesday, and Friday at 2:30 PM. Which cron expression should be used?

Accepted Answer

30 14 * * 1,3,5. Cron uses five fields (minute, hour, day-of-month, month, day-of-week). 2:30 PM is 14:30 in 24-hour format, so minute=30 and hour=14. The day-of-week field uses 0-7 (0 and 7 = Sunday), with Monday=1, Wednesday=3, Friday=5. The asterisks for day-of-month and month mean 'every day' and 'every month', so the expression `30 14 * * 1,3,5` runs the script at 2:30 PM on Monday, Wednesday, and Friday.

Answer

30 14 * * 1-5

Answer

14 30 * * 1,3,5

Answer

30 14 * * 0,2,4

Question 7

A Red Hat Enterprise Linux server has been configured with a custom repository for offline updates. The administrator runs 'yum repolist' and the custom repository is not listed. Which command should be used to verify that the repository configuration file is valid and located in the correct directory?

Accepted Answer

cat /etc/yum.repos.d/custom.repo. The most direct way to verify that a repository configuration file is valid and located in the correct directory is to check its presence and syntax using 'cat /etc/yum.repos.d/custom.repo'. The repository configuration files must reside in /etc/yum.repos.d/ and have a .repo extension; if the file is missing or malformed, 'yum repolist' will not list the repository. This command simply reads the file, allowing the administrator to confirm its location and inspect its contents for errors.

Answer

yum repoinfo

Answer

yum check-repo

Answer

yum-config-manager --dump

Question 8

Which two commands can be used to display the contents of a compressed .tar.gz archive without extracting it? (Choose two)

Accepted Answer

tar -tzf archive.tar.gz. `tar -tzf` lists the contents of a gzip-compressed tar archive without extracting it. The `-t` flag tells tar to list the table of contents, `-z` handles the gzip decompression on the fly, and `-f` specifies the archive file. This is the standard way to inspect a .tar.gz file's contents without extraction.

Answer

gzcat archive.tar.gz

Answer

less archive.tar.gz

Answer

tar -xf archive.tar.gz

Question 9

Which three of the following are valid methods to view the manual page for the 'ls' command? (Choose three)

Accepted Answer

man ls. The 'man' command is the primary method for viewing manual pages in Linux. Running 'man ls' displays the full manual page for the 'ls' command, including its description, options, and usage details.

Answer

help ls

Answer

whatis ls

Question 10

A system administrator is trying to compress the contents of the directory /home/user/project into a tarball named project_backup.tar.gz using the command: tar -czf project_backup.tar.gz /home/user/project. The command completes without errors, but when the administrator tries to list the contents of the tarball using tar -tzf project_backup.tar.gz, it shows a leading slash (/) in the paths, like /home/user/project/file1. The administrator wants to create the tarball with relative paths instead. What change should be made to the tar command?

Accepted Answer

Use tar -czf project_backup.tar.gz -C /home/user project. The `-C` option changes the working directory to `/home/user` before archiving, so the argument `project` is interpreted as a relative path. This strips the leading slash and stores paths like `project/file1` instead of absolute paths. The `-C` option is the standard way to create tarballs with relative paths in a single command.

Answer

Use tar -czf project_backup.tar.gz --absolute-names /home/user/project

Answer

Use tar -czf project_backup.tar.gz -P /home/user/project

Answer

Use tar -czf project_backup.tar.gz -h /home/user/project

Question 11

An administrator notices that the /tmp directory is filling up quickly. They want to find all files in /tmp that are larger than 100 MB and owned by user 'ftp', then delete them. The administrator runs: find /tmp -type f -size 100M -user ftp -exec rm {} \;. However, this command deletes only files that are exactly 100 MB, not larger. Which find expression should be used instead?

Accepted Answer

find /tmp -type f -size +100M -user ftp -exec rm {} \;. The `find` command uses `+` before a size value to match files larger than that size, not exactly equal. The original command omitted the `+`, so it matched only files exactly 100 MB. Adding `+100M` correctly selects files larger than 100 MB.

Answer

find /tmp -type f -size 100M -user ftp -exec rm {} \;

Answer

find /tmp -type f -size +100M ! -size 100M -user ftp -exec rm {} \;

Answer

find /tmp -type f -size +100M -size -100M -user ftp -exec rm {} \;

Question 12

A system administrator is troubleshooting a cron job that runs a script as root. The script is located at /root/scripts/backup.sh and has permissions 755. The cron job is defined in /etc/crontab with the line: 0 2 * * * root /root/scripts/backup.sh. However, the script does not run at the scheduled time. The administrator checks the cron logs and finds no errors. The administrator then runs the script manually as root and it executes successfully. What is the most likely cause of the cron job not running?

Accepted Answer

The cron job line uses absolute path to the script but the script requires an environment variable that is not set in cron's minimal environment.. Cron jobs run with a minimal environment, setting only a few variables (such as HOME, SHELL, LOGNAME, and a default PATH) and not sourcing the user's shell startup files. The script at /root/scripts/backup.sh may rely on an environment variable (e.g., a database password or directory path) defined in root's interactive shell but not in cron's environment. When run manually as root, the variable is available, but cron does not source /root/.bashrc or /root/.bash_profile, causing the script to fail silently or not execute as expected.

Answer

The script is not executable by the root user.

Answer

The cron daemon is not running.

Answer

The /etc/crontab file does not allow running scripts from /root.

Question 13

Which TWO commands can be used to view the kernel ring buffer?

Accepted Answer

dmesg. The kernel ring buffer stores kernel-related messages, such as hardware driver and boot messages. The `dmesg` command is specifically designed to print or control this buffer, making it a direct and correct tool for viewing kernel ring buffer messages.

Answer

journalctl -f

Answer

cat /var/log/messages

Answer

systemctl status

Question 14

What does the 's' in the owner execute position indicate?

Accepted Answer

SetUID. In Linux file permissions, the 's' in the owner execute position (e.g., `-rwsr-xr-x`) indicates the SetUID (Set User ID) special permission. When set on an executable file, it allows the process to run with the effective user ID of the file's owner (typically root), rather than the user who launched it. This is why option E is correct.

Answer

Mandatory access control

Answer

SetGID

Answer

Sticky bit

Answer

No special permission

Question 15

A system administrator notices that a server is responding slowly. The administrator runs `top` and sees a process named `backup_script` consuming 95% CPU. The process runs as root and is supposed to run nightly backups. However, the system load average is low. The administrator wants to investigate without killing the process. Which of the following is the best course of action?

Accepted Answer

Use `renice -n 19 -p ` to lower the priority of the process.. `renice -n 19 -p ` lowers the CPU scheduling priority of the running `backup_script` process to the lowest possible value (19), which reduces its CPU consumption without killing it. This allows the administrator to investigate the cause of the high CPU usage while minimizing the impact on other processes and system responsiveness.

Answer

Use `nice -n 19 ./backup_script` to start the process with lower priority next time.

Answer

Use `chrt -i 0 <PID>` to set the scheduling policy to idle.

Answer

Use `kill -STOP <PID>` to pause the process and then resume later.