# To mount a drive by its ID, what command would you use first to retrieve it? - [ ] df -h - [ ] listid - [ ] ls -l - [x] blkid # Linux file access control lists (ACLs) are \_. - [x] discretionary access control system permissions layered over standard Linux permissions - [ ] mandatory access control system permissions layered over standard Linux permissions - [ ] a type of firewall for Linux - [ ] the same as standard Linux permissions # When using iproute2, how do you show routing information for an IPv6 network? - [ ] route -ipv6 - [ ] route - [x] ip -6 route show - [ ] ip route show # What does this command string do? ```bash find / -size +10M -exec ls -l {} ; ``` - [ ] It finds all files using ls -l and hands them off to the find command to display. - [ ] It finds all files older than 10 minutes and long lists them using the ls command. - [x] It finds all files larger than 10 MB and long lists them using the ls command. - [ ] It uses the ls command to find all files in the filesystem matching the {} wildcard. # What would this locate command show? ```bash locate --regexp '^/usr.*pixmaps.*jpg$' ``` - [ ] all files in a directory named pixmaps - [ ] all files ending in ".jpg" - [x] all file paths that start with "/usr", include the word "pixmaps", and end with ".jpg" - [ ] all file paths that include "/usr/pixmaps" and end with ".jpg" # Which command allows you to do packet analysis from the command line? - [ ] wireshark - [ ] ethtool - [ ] netstat - [x] tcpdump # Which command will tell you how long a system has been running? - [ ] log - [x] uptime - [ ] runtime - [ ] access # How would you describe PCP (Performance Co-Pilot)? - [ ] It is an application testing suite used to profile programming code. - [ ] It is a local command used for monitoring local system resources in real time. - [x] It is a set of tools, services, and libraries for gathering and analyzing performance measures. - [ ] It is a tool designed to change system configuration for purposes of optimization. # You want to resolve a long list of DNS names using dig. What should you do? - [x] Create a text file including all names and use the -f option of dig. - [ ] Type in each query manually. - [ ] Write a shell script to send multiple dig queries to the DNS server. - [ ] Save the DNS names in an SQL database and process it with dig. # What would this command output? ``` ps -e --format uid,pid,ppid,%cpu,cmd ``` - [x] the user ID, process ID, parent process ID, CPU usage, and command name of a process - [ ] the user ID, group ID, parent process ID, CPU usage, and command name of a process - [ ] the UUID, process ID, parent process ID, CPU usage, and command name of a process - [ ] all of these answers # Which command in Bash executes the last line in the shell history that starts with ls? - [ ] ! - [ ] !! - [ ] !\* - [x] !ls # The ssh-copy-id command copies \_ to the remote host. - [ ] both private and public keys - [x] the ssh public key - [ ] the ssh private key - [ ] a fingerprint file # What command is used to determine the amount of disk usage for a directory? - [ ] find - [ ] fdisk - [x] du - [ ] df # A backup drive was created using dd to make a bit-for-bit copy. When the drive is inserted into an iSCSI target before it is booted up, the data appears to be missing. What happened? - [ ] The backup drive is corrupted and needs to be re-created. - [x] When the backup drive was duplicates, the label was as well. When booted, the system mounted the old duplicates drive by its identical label. - [ ] There is a conflict between the physical location of the backup drive and the original drive. - [ ] The backup process went wrong, and the old drive was duplicates over the original drive. # What is the key difference between a redirect (>) and piping to the tee command? - [ ] The tee command sends output only to STDOUT and STDERR. - [ ] A redirect sends output to STDOUT and a file, whereas a tee sends output only to STDOUT. - [ ] Nothing, they are the same. - [x] The tee command sends output to STDOUT and a file, whereas a redirect sends output only to a file. # What does the /etc/nsswitch.conf file manage? - [ ] priority of one DNS server over another - [ ] per network interface DNS server configuration - [ ] alternative DNS services - [x] sources for name service information # Assume the variable myNumber holds a string consisting of 10 digits. What will this command output? ```bash echo \$myNumber | sed -e 's/^[[:digit:]][[:digit:]][[:digit:]]/(&)/g' ``` - [ ] It will only match digits—and since the string has only digits, the command will output the same number without changes. - [ ] It will output the same 10-digit number, but every digit will be inside parentheses. - [ ] It will output the entire 10-digit number inside parentheses. - [x] It will output the same 10-digit number, but the first 3 digits will be inside parentheses. Note: check the question below for a variant of this sed expression. # What would this sed command do? ```bash sed -E 's/[a-Z]{4}/(&)/' textfile.txt ``` - [ ] It would substitute the letter with an ampersand (&). - [ ] It would replace all letters in the textfile.txt file with ampersand (&). - [ ] It would replace the first four letters with an ampersand (&). - [x] It would place parentheses around the first four letters of each line of textfile.txt. Note: check the question above for a variant of this sed expression. Side note: this sed expression may fail with "sed: -e expression #1, char 15: Invalid range end" (for example on MINGW64 / Git Bash); if this is the case, you can try the alternative range `[A-z]`. # Packages can be downloaded but not installed with yum or dnf by specifying which option? - [ ] None of these answers. yum does not support downloading packages without installing them. - [ ] --downloaddir - [ ] -d - [x] --downloadonly # What character class is equal to this set? `[0-9]` - [ ] `[[:alnum:]]` - [x] `[[:digit:]]` - [ ] `[[:alpha:]]` - [ ] `[[:num:]]` # When archiving files, which command will preserve all file attributes including ACLs and SELinux security context? - [ ] zip - [x] tar - [ ] archive - [ ] gzip # In a systemd-based OS, you can change the system hostname by editing /etc/hostname manually and then doing what? - [ ] Restart dhcpd. - [ ] Run /etc/hostname. - [x] Nothing, the system notices automatically. - [ ] Notify systemd to update it by restarting the systemd-hostnamed service. # What command would you use to resize an LVM volume group to include an additional physical volume? - [ ] vgadd - [ ] vgresize - [ ] vgappend - [x] vgextend # When would this system cron job run its task? `0 1 \* \* \*` - [ ] every minute of the hour - [ ] every hour of every day - [x] every day at 1:00 AM - [ ] only on Mondays # ifconfig has been deprecated. What command is now recommended for changing IP addresses in the live config? - [ ] netconf - [ ] ipconfig - [ ] ipman - [x] ip # You are managing an Apache web server on a system using SELinux. By default it cannot read personal webpages in users' home directories. What SELinux boolean would you set to allow this? - [ ] apache_enable_homedirs - [ ] httpd_enable_userdirs - [x] httpd_enable_homedirs - [ ] httpd_enable_userhome_dirs # Why doesn't passwd -l keep a user from logging in via other methods? - [ ] The passwd command is not used for locking passwords. - [ ] There is no password -l option. - [x] It locks only the password, not the account, so users can still authenticate with keys or other methods. - [ ] It does lock the account, keeping users from logging in even if they are using other authentication methods. # In the Bash shell, what is the difference between piping into | and piping into |&? - [ ] Piping into | pipes both stdout and stderr. Piping into |& pipes only stderr. - [x] Piping into | pipes stdout. Piping into |& pipes stdout and stderr. - [ ] Piping into | pipes both stdout and stderr. Piping into |& pipes only stdout. - [ ] Piping into | pipes stdout. Piping into |& pipes all open file descriptors. # Why is the passwd command able to modify the /etc/passwd file? - [ ] The kernel identifies it as one of the names of extended commands. - [ ] It has the same name as the file it modifies. - [x] It has the SUID permission mode and is owned by root. - [ ] It is a system administration command. # When a user deletes a file using the rm command, Linux will \_. - [ ] always ask for confirmation - [ ] back up the file before it deletes the file - [x] ask for confirmation if configured to do so - [ ] never ask for confirmation # What is a major advantage of using Logical Volume Management (LVM)? - [ ] Access to a drive is faster than with standard partitions. - [ ] Volumes can be resized smaller without unmounting them. - [ ] Repairing filesystem errors is easier than with standard partitions. - [x] Volumes can be resized even if the free space is not contiguous. # What is one major difference between brace expansion and globs? - [ ] Globs create a list; brace expansion matches pattern. - [ ] Brace expansion requires files to exist; globs do not. - [x] Brace expansion creates a list; globs match the list of pathnames. - [ ] Globs get processes first and brace expansion later. # To remove all ACLs from a directory , use setfacl with which options? - [ ] -d - [ ] -k - [x] -b - [ ] -x # Which choice will _not_ print "Hello World" in the terminal? - [ ] A ```bash myVar = 5 [[ $myVar -lt 10 ]] && echo " Hello World" ``` - [x] B ```bash myVar = 5 [[ $myVar -lt 10 ]] || echo " Hello World" ``` - [ ] C ```bash myVar = 5 [[ ! $myVar -gt 10 ]] && echo " Hello World" ``` - [ ] D ```bash myVar = 5 [[ $myVar -gt 10 ]] || echo " Hello World" ``` # What is not inherited by child process? - [x] shell aliases - [ ] userid - [ ] environmental variables - [ ] scheduling priority # What NFS option allows the root user to access NFS shares as the root user? - [ ] no_admin_squash - [x] no_root_squash - [ ] allow_root_access - [ ] all_squash # You send an email to a remote client using the following syntax. What will be in the body of the email? ```bash date | mail -s "This is a remote test" [email protected] ``` - [ ] "This is a remote test" - [ ] the date, the time, and the words "This is a remote test" - [ ] The email subject shows "This is a remote test" but the body of the email will be empty. - [x] the current date and time # What is the /etc/hosts file used for? - [ ] resolving the local name - [ ] blocking sites using iptables - [ ] setting the hostname - [x] configuring DNS name servers # In an extended regular expression, you would use (pattern){3} to match three instances of the pattern. How would you match the same thing with an extended glob? - [ ] 3(pattern) - [ ] {0,3}(pattern} - [x] Occurrence quantifiers are not supported in Bash's version of extended globs, so this is not possible. - [ ] {3}(pattern}) # When configuring a Samba share, how would the engineering group be specified in the smb.conf? - [ ] Samba uses Linux operating system groups from the /etc/group file; just specify the group name. - [ ] It would be preceded by a percent sign (%), such as %engineers. - [ ] Use the group name by itself; Samba checks for its existence. - [x] It would be preceded by an @ symbol, such as @engineering. # To configure the Kerberos client, which command should you use to import the keytab file? - [ ] krb5-workstation - [x] ktutil - [ ] pam_krb5 - [ ] kdb5_util # To search from the current cursor position up to the beginning of the file using VIM, type \_ and then the search criteria. - [x] `?` - [ ] `\` - [ ] `/` - [ ] `/search` # What is the job of the NetworkManager daemon? - [ ] It is a graphical tool that manages network connections, including bonding and wireless networks. - [ ] It is a security service that manages user access control of local network-aware services. - [ ] It attempts to keep an active network connection available at all times. - [x] It is a command-line tool that manages network connections. # Why might would you use the usermod command ? - [ ] to log out a user - [ ] to lock a user's account - [x] to change global user account settings - [ ] to set a user's password # Extending an LVM volume group does what to the formatted filesystem? - [ ] It prepares the filesystem for use by defragmenting it. - [ ] It resizes the filesystem to match the volume group size. - [x] It does nothing. - [ ] It remounts the filesystem with the new size. # Which kernel module do you need to load to use interface bonding? - [x] bonding. - [ ] team. - [ ] netbond. - [ ] bond. # What does this command string do? ```bash find / -size -10K -exec ls -l {} \; ``` - [ ] It finds all files larger than 10k and long lists them using the ls command. - [ ] It finds all files of size 10k using ls -l and hands them off to the find command to display. - [ ] It finds all files in the / directory of size 10k and long lists them. - [x] It finds all files in the file system smaller than 10k and long lists them using the ls command. # To change the priority of multiple swap partitions, which file would you edit? - [ ] /proc/swapiness - [x] /etc/fstab - [ ] /etc/mounts - [ ] /etc/swaps # What would you type to list all systemd service unit files, whether they are enabled or not? - [ ] systemctl list-services. - [ ] chkconfig --list-all - [x] systemctl list-unit-files -at service - [ ] systemctl list-unit-files -t service # You can set Linux group passwords using which command? - [x] gpasswd - [ ] passwd - [ ] editsam - [ ] grouppass # With most GNU commands, if an option is a word, what will it be preceded by? - [x] two dashes - [ ] a backslash - [ ] one dash - [ ] nothing # What would happen if you have a script file named script that takes a long time to complete, and you type `nohup ./script &` in the command line? - [ ] The script will remain running in the background even if you reboot the system. - [ ] The script will run in your terminal and you will not be able to do anything until it completes. - [ ] The script will run in the background until you end the session. - [x] The script will run in the background and will continue running even if you end the session. Reference: [Wikipedia](https://en.wikipedia.org/wiki/Nohup) > nohup is a POSIX command which means "no hang up". Its purpose is to execute a command such that it ignores the HUP (hangup) signal and therefore does not stop when the user logs out. # To elevate privileges using the `sudo` command, a user must **\_**. - [ ] enter the root user's password - [x] enter their own password - [ ] enter the sudo user's password - [ ] change to the root group [A Cloud Guru's Blog](https://acloudguru.com/blog/engineering/linux-commands-for-beginners-sudo#:~:text=Sudo%20asks%20for%20your%20user%20password.%C2%A0%20Note%20that%20it%20is%20asking%20for%20your%20password%2C%20not%20the%20root%20password.) # When would this system cron job run its task? `0 22 * * 1-5` - [ ] on the 22nd of every month from June to May - [x] at 10:00 PM Monday to Friday - [ ] every 22 minutes every day except weekends - [ ] from 1:00 AM to 5:00 AM on the 22nd of every month # How does TCP Wrappers differ from a firewall? - [ ] Firewalls are only service specific, whereas TCP Wrappers can block all traffic. - [ ] TCP Wrappers works at the network layer, so it blocks traffic before the firewall even sees it. - [ ] Firewalls easily spawn commands to operate on connection data, whereas TCP Wrappers cannot. - [x] TCP Wrappers works at the application layer, so it can make access decisions on encrypted data. **Note:** TCP Wrapper works on Application Layer but answer is not too much confirmed. # As root, you set execute permissions for user, group, and other on a directory. Now users can do what? - [ ] They can execute files in it. - [x] They can traverse it. - [ ] They can read files in it. - [ ] They can delete files in it. **Note:** This is correct because of the keyword "directory". More info at: https://www.tutorialspoint.com/unix/unix-file-permission.htm # What will this command print? `echo "Thu Jun 4 15:45:45 PDT 2020" | cut -f3 -d" "` - [ ] It will print nothing. - [ ] Thu Jun 4 15:45:45 PDT 2020 - [ ] 0.6567708333333333 - [x] 4 # How can you improve this code snippet? ``` if ls /etc/passwd &> /dev/null then echo "exists" fi ``` - [ ] The code snippet cannot be improved, this is a valid way of checking for the existence of a file. - [x] Use Bash's built-in `[[ ]]` test conditions instead of the ls command. - [ ] The redirect to `/dev/null` will silence the return code invalidating the conditional. Removing the redirect will solve this. - [ ] The ls command will output the name of the file to the screen. Running ls in quiet mode will improve the code snippet. # Using a systemd-based distribution, you want to restrict the cron service from running either automatically or manually. Which command would you run? - [ ] systemctl disable crond - [ ] systemctl disallow crond - [x] systemctl mask crond - [ ] systemctl stop crond **Note:** This is the correct answer because "mask" prohibits all kinds of activation of the unit, including manual activation. [Reference](https://www.commandlinux.com/man-page/man1/systemctl.1.html) : search "mask". # What issue might a user have when they mount a filesystem by partition path such as /dev/sdal in the /etc/fstab file? - [x] The device order may change on boot, resulting in a system that will not boot properly. - [ ] The user may run out of device letters. - [ ] There are no issues with referring to partitions by their partition path. - [ ] It is more difficult identifying mounted devices by partition path. [Reference](https://access.redhat.com/discussions/6004221) # Which option would you choose to force grep to use a basic regular expression (BRE)? - [ ] grep -E - [ ] grep -B - [ ] grep -e - [x] grep -G **Explanation**: Man page of grep command. # An rsyslogd filter determines which items in a log file to act on. What is it made up of? - [ ] a facility and an action - [x] a filter and an action - [ ] a facility and a priority - [ ] a filter and a priority [Reference](https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/system_administrators_guide/ch-viewing_and_managing_log_files) # Which choice is a Network Manager tool used to configure network connections from the GUI? - [ ] nmcli - [ ] ip - [ ] Onmtui - [x] nm-connection-editor # What will not happen if you run the make command without parameters? - [x] It will clean up all previously generated binaries and perform a new build. - [ ] It will run rules of compilation and building. - [ ] It will look for a file called makefile in your current directory. - [ ] It will build only programs that need to be rebuilt. # Most commands that support SELinux use which option to display SELinux security context? - [ ] -S - [ ] --selinux - [ ] --MAC - [x] -Z # What is the difference between the whoami and logname commands? - [ ] whoami and logname provide the same information. - [x] whoami tells who are you currently, and logname tells who you were when you logged in initially. - [ ] logname specifies the name of the login log file, and whoami prints the logged in username. - [ ] whoami shows you who logged in as initially, and logname shows who are you currently. # What is the command to create an associative array in Bash? - [ ] declare -a - [ ] aarray - [ ] array -a - [x] declare -A # What tool Should you use to replace a physical volum in LVM? - [ ] lvcopy - [ ] tar - [x] pvmove - [ ] cp # What is the difference the `==` and `=~` comparison operators when used in BASH double square bracket `if` conditionals? - [x] The `==` operator performs a string comparison; `=~` performs a regex comparison. - [ ] The `==` operator performs a string comparison; `=~` performs a glob pattern comparison. - [ ] The `=~` operator performs a string comparison; `==` performs a regex comparison. - [ ] There is no `=~` operator in BASH `if` conditionals. # What is the difference between these two lines of code? ```shell echo "data" | tee -a file.txt echo "data" >> file.txt ``` - [x] The first line will append the word `data` to file.txt and output it on the screen. The second line will append the word `data` only to file.txt. - [ ] They are the same. - [ ] The first line will append the word `data` to file.txt and there will be no output on the screen. The second line will output the word `data` on the screen and append it to `file.txt` - [ ] Both lines will overwrite file.txt with the word data. # Using backreferences in a POSIX regular expression, which word would this pattern match? ```shell (ss).*\1 ``` - [ ] addressee - [x] possess - [ ] barrenness - [ ] successfully # To run CGI scripts with Apache, you need to **\_**. - [ ] compile the script with a CGI compiler - [ ] make the script executable - [x] make the script executable and set the `httpd_enable_cgi` SELinux boolean - [ ] change the ownership of the script to Apache [reference here](https://selinuxproject.org/page/ApacheRecipes#Allow_the_Apache_HTTP_Server_to_run_CGI_scripts) # To permanently add NAT to the default zone using firewalld, you would use which command string? - [ ] `firewall-cmd --permanent --add-nat` - [x] `firewall-cmd --permanent --add-masquerade` - [ ] `firewall-cmd --zone=default --add-nat` - [ ] `firewall-cmd --zone=default --add-masquerade` [reference here](https://www.rootusers.com/how-to-use-firewalld-rich-rules-and-zones-for-filtering-and-nat) # What is the difference between using `=` and `==` in a BASH double square bracket `if` conditional? ``` if [[ $FILE == $GLOB ]] ;then ``` - [ ] The single equal sign (`=`) is an assignment operator; the double equal sign (`==`) checks equality. - [x] There is no difference. - [ ] The single equal sign (`=`) checks equality; the double equal sign (`==`) checks string equality. - [ ] The double equal sign (`==`) is an assignment operator; the single equal sign (`=`) checks equality. [reference here](https://stackoverflow.com/a/12948608) # `journald` differs from traditional logging services such as `rsyslogd` and `syslogd` because its logs are **\_** by default. - [ ] stored remotely - [ ] text - [x] persistent - [ ] not persistent [reference here](https://sematext.com/blog/journald-logging-tutorial/#toc-journald-storage-4) # What is the purpose of a Mail Transport Agent (MTA)? - [ ] It transports the mail from user's computer to the mail server. - [ ] It accepts mail and adds it to the mail queue for further processing. - [ ] It stores the mail in a mail queue waiting for the MUA to download it. - [x] It transports mail from one mail server to another. # What do you need to do before you can perform SSH passwordless logins? - [x] Generate RSA or DSA key pairs using ssh-keygen. - [ ] Change the remote user's password. - [ ] Create a local SSL certificate. - [ ] Change the remote SSH configure to allow it. [Reference](https://phoenixnap.com/kb/setup-passwordless-ssh) # When installing a downloaded package on the RedHat-based distribution manual using RPM, what may you have to do first? - [ ] Compile the package source code. - [x] Download all dependencies and install them before installing the desired package. - [ ] Agree to an end-user license agreement. - [ ] provide the --resolve option so RPM resolves all packages dependency. **[Explanation:](https://access.redhat.com/discussions/2026743)** Rpm is not meant to resolve dependencies. It checks whether required software (versions) are installed and fails when software is missing and when the wrong version of software is installed. # With GNU tools such as a GNU grep, awk, and sed, what is the difference between basic regular expressions (BREs) and extended regular expressions (EREs)? - [ ] EREs can match the groups. - [ ] EREs support occurrence operators. - [ ] ERE's support alternation. - [x] only the syntax differs. [Reference](https://www.gnu.org/software/sed/manual/html_node/BRE-vs-ERE.html) # What is the difference between reading the list of disk partitions from `/proc/partitions` and getting it using `fdisk -l`? - [ ] `/proc/partitions` represents the disk partition table more accurately than `fdisk -l` - [ ] `/proc/partitions` shows only mounted drives. `fdisk -l` shows all drivers. - [ ] There is no difference between the two, and both lists contain the same data. - [x] `/proc/partitions` is the kernel's list of partitions held in ram. `fdisk -l` reads the partition table from the drive itself. # What would be in out.txt? cat < in.txt > out.txt - [x] the content of in.txt. - [ ] the output from the command line. - [ ] Nothing, because you cannot redirect from a file (in.txt) to another file (out.txt). You can redirect only from a command to a file. - [ ] Nothing, The redirect will create a new empty file, but there will not be any output from the cat command to redirect. # Using alternation in a POSIX-extended regular expression, which numbers would this pattern match? ``` ^(([0-9][0-9]?)|(2[0-9][0-9]))$ ``` - [x] 0-99 and 200-299 - [ ] 0-99 - [ ] 200-299 - [ ] 0-299 # Typing `systemctl enable crond` does what to the crond service? - [ ] Starts the crond service now. - [ ] Allows user to start the crond service. - [ ] Unmasks the crond service. - [x] Ensures that the crond service starts automatically on bootup. # Which of these features is missing from the Bash Language? - [ ] associative arrays. - [ ] extended regular expressions. - [ ] debug traps. - [x] object orientation. # What is the first step to integrate extended globs into your command-line workflow? - [ ] Nothing, extended globs are already integrated into the shell and turned on automatically. - [x] Make extended globs persistent by adding `shopt -s extglob` to a shell startup file. - [ ] Type `shopt -s extglob` into a shell one time to set the option on permanently. - [ ] Make extended globs persistent by adding `shopt +s extglob` to a shell startup file. # Which statement about default ACLs is true? - [x] They provide inheritance for user and group permissions. - [ ] They work only on files. - [ ] They provide inheritance for group ownership. - [ ] They grant access to the directory on which they are set. [reference:](https://www.redhat.com/sysadmin/linux-access-control-lists#setting-an-acl) # The object that `systemd` uses to manage services is called a \_ file. - [x] unit - [ ] service - [ ] single - [ ] process # What tool should you use to replace a physical volume in LVM?What tool should you use to replace a physical volume in LVM? - [ ] cpcp - [ ] pvmovepvmove - [ ] tartar - [ ] lvcopy # What is the difference between the apt remove and apt autoremove commands? - [ ] The apt remove command is a link to apt autoremove, so there are no differences. - [x] Both uninstall software. The apt autoremove command also uninstalls the dependencies. - [ ] Both uninstall software. The apt remove command also uninstalls the dependencies. - [ ] The apt autoremove command is a system service that routinely removes unused software packages. [reference](https://dannyda.com/2021/08/19/whats-the-difference-between-apt-remove-and-apt-autoremove-what-is-apt-purge-when-to-use-debian-ubuntu-kali-linux-etc/) # You want to extract the contents from an rpm package. Which command do you use? - [ ] rpm --update - [ ] rpm -ivh --force - [ ] rpm --reinstall - [x] rpm2cpio 1. [reference:](https://stackoverflow.com/questions/18787375/how-do-i-extract-the-contents-of-an-rpm) 2. [reference:](https://man7.org/linux/man-pages/man8/rpm2cpio.8.html)