RHCSA Essential Command-Line Tools Questions and Answers

Question 1

A system administrator needs to find all files within the `/etc` directory that are owned by the `root` user and have been modified in the last 7 days. Which command will accomplish this?

Accepted Answer

find /etc -user root -mtime -7

Answer

The correct command is `find /etc -user root -mtime -7`. The `find` command searches the specified path (`/etc`). The `-user root` predicate selects files owned by 'root'. The `-mtime -7` predicate selects files whose data was modified less than 7 days ago (i.e., within the last 7 days). `-mtime +7` would find files modified more than 7 days ago, and `-mtime 7` would find files modified exactly 7 days ago.

Question 2

Which of the following commands correctly creates a bzip2-compressed tar archive named `backup.tar.bz2` containing the contents of the `/home/user/data` directory?

Accepted Answer

tar -cjf backup.tar.bz2 /home/user/data

Answer

The correct command is `tar -cjf backup.tar.bz2 /home/user/data`. The `-c` flag is for creating an archive. The `-j` flag specifies bzip2 compression. The `-f` flag is used to specify the output archive filename. The `-z` flag is for gzip compression, `-x` is for extracting, and omitting a compression flag like `-j` or `-z` would create an uncompressed archive.

Question 3

A system administrator needs to search through `/var/log/messages` for lines containing the exact word 'error', but not 'errors' or 'error-code'. Which command should be used?

Accepted Answer

grep -w 'error' /var/log/messages

Answer

The `grep -w 'error' /var/log/messages` command is correct. The `-w` option tells `grep` to select only those lines containing matches that form whole words. A simple `grep 'error'` would match substrings. `grep -v` inverts the match, showing lines that do not contain 'error'. `grep -i` performs a case-insensitive search.

Question 4

An application with PID 2501 is completely unresponsive. The administrator first tried `kill 2501`, but the process did not terminate. What is the most appropriate next command to forcefully stop the process?

Accepted Answer

kill -9 2501

Answer

The command `kill -9 2501` sends the SIGKILL signal. This is a non-catchable, non-ignorable signal that is handled directly by the kernel to terminate the process immediately. The default `kill` command and `kill -15` both send SIGTERM, which is a polite request to terminate that an unresponsive process can ignore. `kill -1` (SIGHUP) typically tells a process to reload its configuration. While `killall -9` could also work, using the specific PID with `kill -9` is more direct when the PID is already known.

Question 5

To perform an in-place replacement of every occurrence of the IP address `10.0.1.50` with `10.0.2.50` within the file `/etc/config.txt`, which `sed` command should be used?

Accepted Answer

sed -i 's/10.0.1.50/10.0.2.50/g' /etc/config.txt

Answer

The correct command is `sed -i 's/10.0.1.50/10.0.2.50/g' /etc/config.txt`. The `-i` flag modifies the file in-place. The `s/.../.../` is the substitute command. The `g` flag at the end ensures the replacement is global, affecting all occurrences on a line, not just the first. Redirecting output to the same file you are reading from can truncate the file, and omitting the `g` flag will only replace the first match on each line.

RHCSA Exam Practice Test

RHCSA Exam Practice Test

RHCSA Essential Command-Line Tools Questions and Answers