CompTIA Linux+ Certification - (XK0-005) Exam Questions

Correct Answer:

`ping -c 2 -6` is correct. Running `ping -c 2 -6` sends two pings to the remote server via IPv6.

Incorrect Answers:

"`ping -k 2 -ipv6`," "`ping -k 2 -6`," and "`ping --count 2 --six`" are incorrect. The `ping` command does not have `-k`, `-ipv6`, `--count`, or `--six` options.

Correct Answers:

`-e` and `-A` are correct. The `-e` and `-A` options (and the `-a` option to an extent) cause `ps` to display a listing of all processes running on the system, not just those associated with the current terminal session.

Incorrect Answers:

"`-l`, ""`-T`," and "`-f`" are incorrect.`-l` and `-f` are incorrect because the `-l` and `-f` options are used to specify extended information in the output of the command.

`-T` is incorrect because the `-T` option causes `ps` to select all processes associated with the current terminal.

Correct Answer:

`rw-r--r--` is correct. The default mode for new files on Linux is `rw-rw-rw-`. A mask of `0023` subtracts no permissions from _user_, subtracts write (`2`) from _group_, and subtracts write (`2`) and execute (`1`) from _other_. The result is a mode of `rw-r--r--`.

Incorrect Answers:

"`rw-rw-rw-`, ""`rw-r--r-x`," and "`rw-rw-rwx`" are incorrect.

`rw-rw-rw-` is incorrect because it would require a mask of `0000`.

`rw-r--r-x` and `rw-rw-rwx` are incorrect because the execute permission for _other_ is not included in the default file mode.

Correct Answer:

`usermod -L` is correct. Running `usermod -L` locks the users’ accounts and prevents them from logging in. 

Incorrect Answers:

"`usermod -l`," "`usermod -d`," and "`usermod --LOCK`" are incorrect.

`usermod -l` is incorrect because the command `usermod -l` is used to change the login name of a user.

`usermod -d` is incorrect because the `-d` option is used to change the user’s login directory.

`usermod --LOCK` is incorrect because the `--LOCK` option does not exist in Linux, and running it would result in a syntax error (although there is a `--lock` option, which is the same as `-L`).

Correct Answer:

`chage` is correct. Running `chage`, or “change password age,” will update the password expiration dates within the `/etc/shadow` file.

Incorrect Answers:

"`shadow --modify`," "`shadow -m`," and "`shadow`" are incorrect. Linux does not have a command named `shadow`. For your information, `/etc/shadow` is a file only and contains users’ encrypted/hashed passwords and related password expirations.

Correct Answer:

`getenforce` is correct. Running `getenforce` shows whether SELinux is enabled or not.

Incorrect Answers:

"`SELinux --get`," "`SELinux -g`," and "`setenforce -g`" are incorrect.

`SELinux --get` and `SELinux -g` are incorrect because `SELinux` is not a command.

`setenforce -g` is incorrect because running `setenforce` would enable or disable SELinux and would not display the current setting.

Correct Answers:

Execute the command `export -f readinput`. and Place the function in `~/.bashrc` and source the file. are correct. The command `export -f <function_name>` (`export -f readinput`) causes the function to be copied from parent to child process. This change is not persistent. Placing the function in `~/.bashrc` ensures the function is persistent, and sourcing the `~/.bashrc` file makes it active in the current session.

Incorrect Answers:

Place the function in the file `~/.bash_profile` and source the file. is incorrect. The `file ~/.bash_profile` is used to set the user’s working environment.

The file `~/.bashrc` is used to change how the shell runs (`rc` = run commands). 

Place the function in `/etc/bashrc` and source the file. is incorrect. `/etc/bashrc` is used for system-wide Bash run commands. The question specifies the current user.

Correct Answers:

`passwd` and `chage` are correct. The `passwd` command may be used to change password aging parameters. The `chage` command is traditionally used to change all password aging parameters.

Incorrect Answers:

`usermod` is incorrect. The command `usermod` can change the expiration date and number of inactive days of the user account (not the password).

`useradd` is incorrect. The `useradd` command cannot be used to change a user’s parameters.

Correct Answer:

`600` is correct. Permissions for the `aquota.user` file must be set to `600 (rw-------)` and owned by `root`.

Incorrect Answers:

`644` and `744` are incorrect. `644` and `744` would give users read access to the file.  `700` is incorrect. The file should not have executable permissions.

Correct Answers:

`chmod 640 filea` and `chmod g+r filea` are correct. A user must have read permissions to copy a file. `user1` is a member of the group that owns the file. The commands `chmod 640` and `chmod g+r` add read permissions to the group permission set. This allows any member of the group that owns the file to copy it.

Incorrect Answers:

`chmod 040 filea`v is incorrect. The command `chmod 040` would remove the permissions for the owner of the file, but the question specifically states not to modify any other permissions. `chmod g+rw filea` is incorrect. The command `chmod g+rw` would add read and write permissions to the file. Although this would allow `user1` to copy the file, the question specifically states not to modify any other permissions.