EX200 Essential Tools Practice Test 3 — 15 Questions

Question 1

An administrator wants to gracefully terminate a process with PID 12345. Which command should be used?

Accepted Answer

kill -TERM 12345. `kill -TERM` (or `kill -15`) sends the SIGTERM signal, which requests a process to terminate gracefully. This allows the process to perform cleanup tasks (e.g., closing files, releasing resources) before exiting, making it the standard way to stop a process politely.

Answer

kill -STOP 12345

Answer

kill -9 12345

Answer

kill -KILL 12345

Question 2

A system administrator needs to replace all occurrences of 'enabled' with 'disabled' in /etc/ssh/sshd_config, but only on lines that do not start with '#'. Which sed command accomplishes this?

Accepted Answer

sed '/^#/!s/enabled/disabled/g' /etc/ssh/sshd_config. It uses an address range `/^#/!` to negate lines starting with `#` (comments), then applies the substitution `s/enabled/disabled/g` only to non-comment lines. The `!` operator inverts the match, so the command acts on lines that do NOT match the pattern, which is exactly what the requirement specifies.

Answer

sed 's/enabled/disabled/g' /etc/ssh/sshd_config

Answer

sed -n '/^#/!s/enabled/disabled/gp' /etc/ssh/sshd_config

Answer

sed '/^#/s/enabled/disabled/g' /etc/ssh/sshd_config

Question 3

A user wants to display the contents of a file in reverse line order. Which command should be used?

Accepted Answer

tac file. The `tac` command is the standard Linux utility for displaying a file in reverse line order. It reads the file from the last line to the first, effectively reversing the line sequence. This is the correct tool for the task described.

Answer

tail -r file

Answer

sort -r file

Answer

rev file

Question 4

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 5

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 6

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 7

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 8

Which TWO commands can be used to view the contents of a compressed gzip file without decompressing it permanently? (Choose two.)

Accepted Answer

zless file.gz. Both `zcat` and `zless` view the contents of gzip-compressed files without permanently decompressing them. They decompress on the fly and write to standard output or a pager, leaving the original `.gz` file intact. In contrast, `gunzip` and `gzip -d` permanently decompress the file.

Answer

zgrep file.gz

Answer

gunzip file.gz

Answer

gzip -d file.gz

Question 9

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 10

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

Accepted Answer

htop. A is correct because `htop` is an interactive process viewer that by default updates in real-time (every ~1-2 seconds) and allows you to monitor processes dynamically. It provides a color-coded, user-friendly interface with CPU, memory, and swap usage bars, updating continuously without needing a separate interval flag.

Answer

ps aux

Answer

at 2

Question 11

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 12

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 13

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 14

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 15

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