EX200 Essential Tools Practice Test 4 — 15 Questions

Question 1

An administrator needs to measure the execution time of the command 'backup.sh'. Which command prefix should be used?

Accepted Answer

time. The 'time' command is the correct prefix to measure the execution time of a command in Linux. When placed before 'backup.sh', it runs the script and then outputs the real, user, and system time consumed, providing the precise measurement the administrator needs.

Answer

date

Answer

watch

Answer

timeout

Question 2

A user is unable to delete a file named '-f' in the current directory. Which command will successfully remove it?

Accepted Answer

rm -- -f. The '--' double dash signals the end of command options to most Linux utilities, including rm. This allows rm to interpret '-f' as a literal filename rather than the '--force' option, enabling its deletion.

Answer

rm \-f

Answer

rm -f

Answer

rm "-f"

Question 3

An administrator wants to create a symbolic link named 'link_to_hosts' in /tmp that points to /etc/hosts. Which command is correct?

Accepted Answer

ln -s /etc/hosts /tmp/link_to_hosts. The `ln -s` command creates a symbolic link. The correct syntax is `ln -s TARGET LINK_NAME`. Option B correctly specifies the existing target file `/etc/hosts` first, followed by the new link path `/tmp/link_to_hosts`, which creates the symbolic link in `/tmp` pointing to `/etc/hosts`.

Answer

ln -s /tmp/link_to_hosts /etc/hosts

Answer

ln -s /etc/hosts link_to_hosts

Answer

ln -s /tmp/link_to_hosts /etc/hosts

Question 4

An administrator needs to list the permissions, owner, group, and filenames of all files in /var/log, including hidden files, in a human-readable format. Which command does this?

Accepted Answer

ls -lah /var/log. `ls -lah /var/log` combines the `-l` (long format), `-a` (show all files including hidden ones), and `-h` (human-readable sizes) flags. This meets all requirements: listing permissions, owner, group, filenames, and hidden files with sizes in KiB/MiB/GiB.

Answer

ls -lh /var/log

Answer

ls -la /var/log

Answer

ls -ld /var/log

Question 5

Which THREE actions will create a new empty file named 'testfile' in the current directory? (Choose three.)

Accepted Answer

> testfile. The shell redirection operator `>` without a preceding command truncates or creates the specified file. When used alone, `> testfile` opens 'testfile' for writing, which creates an empty file if it does not exist, or truncates it to zero length if it does. This is a standard POSIX shell feature.

Answer

ls > testfile

Answer

echo "content" > testfile

Question 6

Which THREE commands can be used to monitor real-time process status and update the display every 2 seconds? (Choose three.)

Accepted Answer

htop. Option A, htop, is correct because it is an interactive real-time process viewer that continuously refreshes its display (by default every second, and its refresh interval is configurable), so it can monitor process status in real time. Option B, top -d 2, is correct because top is the classic real-time process monitor and the -d 2 flag explicitly sets the screen update delay to 2 seconds. Option D, watch -n 2 ps aux, is correct because watch repeatedly executes the given command at a fixed interval, and -n 2 makes it rerun ps aux every 2 seconds, producing a refreshed process listing. Option C, ps aux, is not correct because ps is a one-shot snapshot command that prints process information once and exits, with no continuous refresh. Option E, at 2, is not correct because at is a job-scheduling utility for running commands at a specified future time, not a real-time process monitoring tool.

Answer

ps aux

Answer

at 2

Question 7

Refer to the exhibit. What does the file permission -rw------- indicate about /etc/shadow?

Accepted Answer

Only root user can read and write; others have no access.. The permission string `-rw-------` breaks down as: owner (root) has read (4) and write (2) permissions, and no execute (0); group has no permissions (---); others have no permissions (---). Since `/etc/shadow` is owned by root, only the root user can read and write the file, while all other users (including group members and others) have zero access. Option D correctly states this.

Answer

Root user can read, write, and execute; group and others have no access.

Answer

Owner can read and write; group can read; others can read.

Answer

Owner can read; group can read; others cannot access.

Question 8

Refer to the exhibit. Why did the sshd service fail?

Accepted Answer

The service start was requested too many times in quick succession.. B is correct because systemd's `StartLimitIntervalSec` and `StartLimitBurst` settings (default: 10 seconds and 5 starts) prevent rapid service restarts. When `sshd` fails repeatedly within the interval, systemd marks it as failed with the status 'start-limit-hit' to avoid resource exhaustion from restart loops.

Answer

The service binary is missing.

Answer

The configuration file /etc/ssh/sshd_config has a syntax error.

Answer

The system ran out of memory.

Question 9

Refer to the exhibit. The backup script runs every 5 minutes but generates errors. What is the most likely cause?

Accepted Answer

The script is not executable.. The cron job fails because the script lacks execute permissions. Cron requires that scripts specified in crontab entries have the executable bit set (chmod +x) for the user under whose crontab the job runs. Without this, the cron daemon cannot spawn the script as a process, resulting in errors.

Answer

The script is owned by root.

Answer

The cron daemon is not running.

Answer

The script uses absolute paths.

Question 10

A system administrator needs to view the last 10 lines of the log file /var/log/messages in real time as new lines are added. Which command should be used?

Accepted Answer

tail -f /var/log/messages. The `tail -f /var/log/messages` command displays the last 10 lines of the file by default and then continues to output new lines as they are appended, providing real-time monitoring. The `-f` (follow) option keeps the file open and polls for changes, making it the correct tool for live log watching.

Answer

less /var/log/messages

Answer

head -n 10 /var/log/messages

Answer

cat /var/log/messages

Question 11

A system administrator runs the command 'ls -l' and sees that a file has permissions '-rwxr-xr-x'. The administrator wants to remove execute permission for the group and others while keeping it for the owner. Which chmod command should be used?

Accepted Answer

chmod go-x file. The command 'chmod go-x file' removes execute permission for group (g) and others (o) while leaving the owner's permissions unchanged. The current permissions '-rwxr-xr-x' indicate owner has rwx, group has r-x, and others have r-x, so removing execute from group and others yields '-rwxr--r--'.

Answer

chmod u-x file

Answer

chmod 755 file

Answer

chmod a+x file

Question 12

An administrator receives an alert that a process named 'apache2' is consuming excessive CPU. The administrator needs to identify the PID of the process and then change its priority to the lowest possible value (least favorable scheduling). Which sequence of commands should be used?

Accepted Answer

pidof apache2; renice -n 19 -p . `pidof apache2` retrieves the PID of the apache2 process, and `renice -n 19 -p ` sets the priority to the lowest possible (least favorable) scheduling value. In Linux, `renice` accepts nice values from -20 (highest priority) to 19 (lowest priority), so 19 is the correct value for the least favorable scheduling.

Answer

pidof apache2; renice -n 20 -p <PID>

Answer

ps -C apache2 -o pid=; renice -n -20 -p <PID>

Answer

ps aux | grep apache2; nice -n 19 <PID>

Question 13

A company policy requires that all cron jobs run by non-root users must be logged to a specific file /var/log/usercron.log. The system administrator decides to use rsyslog to capture these messages. Which configuration directive should be added to /etc/rsyslog.conf or a file in /etc/rsyslog.d/ to achieve this?

Accepted Answer

cron.* /var/log/usercron.log. The cron facility in rsyslog captures messages generated by the cron daemon, including cron jobs run by non-root users. By adding the directive `cron.* /var/log/usercron.log` to the rsyslog configuration, all cron messages (regardless of priority) are logged to the specified file, satisfying the policy requirement.

Answer

user.* /var/log/usercron.log

Answer

*.* /var/log/usercron.log

Answer

authpriv.* /var/log/usercron.log

Question 14

A user wants to set an environment variable named 'EDITOR' to the value '/usr/bin/vim' so that it is available in all future login sessions. Which file should the user add the export command to?

Accepted Answer

~/.bash_profile. The ~/.bash_profile file is executed for login shells, making it the correct place to set environment variables like EDITOR that should persist across all future login sessions. Adding 'export EDITOR=/usr/bin/vim' to this file ensures the variable is defined each time the user logs in.

Answer

~/.bash_logout

Answer

/etc/bashrc

Answer

~/.bashrc

Question 15

An administrator needs to compress a directory containing subdirectories and files into a single archive file, with maximum compression, and exclude all '*.tmp' files. Which command should be used?

Accepted Answer

tar -cjvf archive.tar.bz2 --exclude='*.tmp' /path/to/dir. The question specifies 'maximum compression'. Among common tar compression methods, bzip2 (via the -j flag) typically provides better compression ratios than gzip (-z), though it is slower. Option C uses `tar -cjvf` with the `--exclude` option placed correctly before the source directory, which is the proper syntax for tar exclusions. This command creates a .tar.bz2 archive with maximum compression while excluding all *.tmp files. Option A uses gzip, which offers faster compression but lower ratios, making it incorrect for 'maximum compression'. Options B and D also fail: B has incorrect syntax (--exclude after the directory), and D omits the exclude option entirely.

Answer

tar -czvf archive.tar.gz --exclude='*.tmp' /path/to/dir

Answer

tar -czvf archive.tar.gz /path/to/dir --exclude='*.tmp'

Answer

tar -czvf archive.tar.gz /path/to/dir