101-500 Exam Dumps - LPIC Level 1 Questions and Answers

Systemd is a system and service manager for Linux systems, and it can manage the mounting and unmounting of file systems. Systemd can automatically create and start mount units for file systems that are listed in /etc/fstab or are known to the system. Mount units are unit files that encode information about a file system mount point controlled and supervised by systemd. Mount units must be named after the mount point directories they control, and they have the suffix .mount. For example, the mount point /home must be configured in a unit file home.mount.

Systemd can also handle file systems that are neither listed in /etc/fstab nor known to the system, but are mounted manually by the user. In this case, systemd automatically generates a transient mount unit and monitors the mount point without changing it. A transient mount unit is a unit that is created dynamically and temporarily, and is not backed by a unit file on disk. A transient mount unit has the same name and properties as a regular mount unit, but it is not persistent across reboots. Systemd does not interfere with the manual mount, and does not unmount it unless explicitly requested by the user. The user can use the mount command or the systemd-mount command to create a manual mount, and the umount command or the systemd-umount command to remove it. The user can also use the systemctl command to inspect and control the transient mount unit. For example, to show the status of the transient mount unit for the mount point /mnt, use the following command:

systemctl status mnt.mount

A hard link is a directory entry that refers to the same inode as another file. An inode is a data structure that stores the metadata and the location of the data blocks of a file. A hard link allows multiple names to refer to the same file content, as long as they are on the same filesystem. Therefore, when a hard link is created, the inode reference count is increased by one, and when a hard link is deleted, the inode reference count is decreased by one. The file content is only removed from the disk when the inode reference count reaches zero, meaning that there are no more hard links to the file. In this scenario, after successfully creating a hard link called bar to the ordinary file foo, foo and bar both refer to the same inode and the same file content. The inode reference count is two. When foo is deleted from the filesystem, the inode reference count is decreased by one, but it is still one, meaning that there is still one hard link to the file. Therefore, foo would be removed while bar would remain accessible. The file content would not be removed from the disk until bar is also deleted. The other options are either incorrect or not applicable. The user is not prompted whether bar should be removed, too. The bar link would still exist and be usable, not unusable. References:

LPIC-1 Exam 101 Objectives, Topic 103: GNU and Unix Commands, 103.3 Perform basic file management

LPIC-1 Linux Administrator 101-500 Exam FAQ, LPIC-1 Exam 101 Objectives, GNU and Unix Commands (Total Weight: 25)

The properties of a Linux system that should be changed when a virtual machine is cloned are the D-Bus Machine ID and the SSH host keys. The D-Bus Machine ID is a unique identifier for the system that is used by the D-Bus message bus system to communicate between applications. The D-Bus Machine ID is stored in the /etc/machine-id or /var/lib/dbus/machine-id file and it is generated during the first boot of the system. If a virtual machine is cloned without changing the D-Bus Machine ID, it can cause conflicts and errors with the D-Bus services on the clone and the original system. To change the D-Bus Machine ID, the file containing it must be deleted or emptied and the system must be rebooted12. The SSH host keys are cryptographic keys that are used by the SSH protocol to authenticate the identity of the system and establish a secure connection. The SSH host keys are stored in the /etc/ssh directory and they are generated during the first boot of the system or the installation of the openssh-server package. If a virtual machine is cloned without changing the SSH host keys, it can compromise the security and integrity of the SSH connections, as the clone and the original system will have the same keys. To change the SSH host keys, the files containing them must be deleted and the ssh-keygen command must be run to generate new keys34.

The other options are false or irrelevant. The partitioning scheme and the file system are not properties of a Linux system that need to be changed when a virtual machine is cloned, as they do not affect the functionality or the identity of the system. The permissions of /root/ are also not properties of a Linux system that need to be changed when a virtual machine is cloned, as they do not affect the security or the communication of the system. References:

Linux Essentials - Linux Professional Institute Certification Programs1

Exam 101 Objectives - Linux Professional Institute2

How to Clone Virtual Machine in VirtualBox - UbuntuMint3

Chapter 4. Cloning Virtual Machines Red Hat Enterprise Linux 7 | Red …4

 The type command shows the type of a given shell command, which can be one of the following: alias, keyword, function, builtin, or file. For example, type ls will show that ls is an alias for ls --color=auto. The type command can also show the full path of a file command, such as type grep will show that grep is /bin/grep. References: LPI Linux Essentials, type command

The rpm command is used to install, upgrade, query, verify and remove RPM packages on Linux systems. The -U option is used to upgrade an existing package to a newer version, or install a package if it does not exist in the RPM database. The -U option is equivalent to -e (erase) followed by -i (install). The other options are not valid for upgrading a package. The -q option is for querying a package, the -e option is for erasing a package, the --force option is for overriding conflicts, and the -u option is not a valid option for the rpm command. References: Using RPM Command to Install, Upgrade and Remove Packages, Linux package management with YUM and RPM

The directories on a 64 bit Linux system that typically contain shared libraries are /usr/lib64/ and /lib64/. Shared libraries are binary files that provide reusable functions, routines, classes, data structures, and so on for programs and applications. They are loaded into memory before the program starts and shared by multiple processes that use the same library. Shared libraries are usually stored in standard locations in the file system, such as /usr/lib, /usr/local/lib, /lib, and /lib64 for 32 bit systems, and /usr/lib64, /usr/local/lib64, /lib64, and /lib for 64 bit systems12. The /usr/lib64 and /lib64 directories contain the shared libraries for the system and user applications, respectively. The other directories are either non-existent or do not contain shared libraries. The ~/.lib64/ directory is not a standard location for shared libraries, and it is unlikely that a user would have such a directory in their home directory. The /var/lib64/ directory is also not a standard location for shared libraries, and it is usually used for variable data files that are specific to a package or application. The /opt/lib64/ directory is not a standard location for shared libraries, and it is usually used for optional software packages that are installed in the /opt directory3. References:

Linux Essentials - Linux Professional Institute Certification Programs1

Exam 101 Objectives - Linux Professional Institute2

Understanding Shared Libraries in Linux - Tecmint3

The correct command to enable the setuid (suid) permission on the executable /bin/foo is:

B. chmod 4755 /bin/foo

The chmod command is used to change the permissions of files and directories in Linux. The chmod command can take either a symbolic or a numeric mode to specify the new permissions. The numeric mode is composed of four digits, each representing a different set of permissions: the first digit is for the special permissions, such as setuid, setgid, and sticky bit; the second digit is for the user permissions; the third digit is for the group permissions; and the fourth digit is for the others permissions. Each digit can range from 0 to 7, where 0 means no permissions, 1 means execute permission, 2 means write permission, 4 means read permission, and the sum of these values means a combination of permissions. For example, 5 means read and execute permissions, and 6 means read and write permissions.

The setuid permission is a special permission that allows an executable to run with the privileges of the owner of the file, instead of the user who launched it. The setuid permission is represented by the value 4 in the first digit of the numeric mode. For example, to enable the setuid permission on an executable file, use the following command:

chmod 4xxx file

where xxx is the combination of the user, group, and others permissions.

In this question, the executable file is /bin/foo, and the desired permissions are:

setuid permission enabled

user permissions: read, write, and execute

group permissions: read and execute

others permissions: read and execute

Therefore, the numeric mode for these permissions is 4755, where:

4 means setuid permission enabled

7 means user permissions: read, write, and execute

5 means group permissions: read and execute

5 means others permissions: read and execute

The correct command to enable the setuid permission on /bin/foo with these permissions is:

chmod 4755 /bin/foo

This command will change the permissions of /bin/foo to -rwsr-xr-x, where the s in the user section indicates the setuid permission.

The other options are not correct because:

A. chmod 1755 /bin/foo: This command will enable the sticky bit, not the setuid permission, on /bin/foo. The sticky bit is another special permission that prevents users from deleting or renaming files that they do not own in a shared directory. The sticky bit is represented by the value 1 in the first digit of the numeric mode. For example, to enable the sticky bit on a directory, use the following command:

chmod 1xxx directory

where xxx is the combination of the user, group, and others permissions.

C. chmod u-s /bin/foo: This command will disable the setuid permission, not enable it, on /bin/foo. The u-s option is a symbolic mode that means remove the setuid permission from the user permissions. For example, to disable the setuid permission on an executable file, use the following command:

chmod u-s file

D. chmod 755+s /bin/foo: This command is not valid because it mixes the numeric and the symbolic modes, which are not compatible. The 755 is a numeric mode that means user permissions: read, write, and execute; group permissions: read and execute; others permissions: read and execute. The +s is a symbolic mode that means add the setuid and setgid permissions to the user and group permissions, respectively. The chmod command does not accept both numeric and symbolic modes at the same time, and it will fail with an error message saying:

chmod: invalid mode: ‘755+s’ Try ‘chmod --help’ for more information.