Full Access LPI 101-500 Tutorials

The command rpm -qpl apache-ql.rpm is used to preview the list of files that would be installed by the RPM package file apache-xml.rpm. This command queries the package file without installing it and lists the contents of the package. Here’s what each part of the command means:

rpm is the command-line tool used for managing RPM packages on Linux systems.

-qpl are options for the rpm command.

q stands for query mode

l stands for list the contents of the package.

p specifies that the package being queried is not installed, but is a file located on the system.

apache-xml.rpm is the name of the RPM package file you want to query.

So, when you run this command, it will display a list of all the files that are included in the apache-xml.rpm package file, without installing it. This can be useful for checking what files are included in the package before installing it or comparing it with another version of the package.

The other commands are either invalid or do not perform the same function as the correct answer. For example:

rpm -qp apache-xml.rpm will only display the name and version of the package, not the list of files.

rpm -qv apache-xml.rpm will display the verbose information about the package, such as the description, license, and changelog, but not the list of files.

rpm -ql apache-xml.rpm will list the files that are installed on the system by the apache-xml.rpm package, but only if the package is already installed. If the package is not installed, it will return an error.

The correct commands to display all currently mounted filesystems are cat /proc/self/mounts and mount. The cat /proc/self/mounts command reads the contents of the /proc/self/mounts file, which is a symbolic link to /proc/mounts. This file contains information about all the filesystems that are currently mounted on the system, as reported by the kernel. The mount command without any arguments shows all the mounted filesystems, as recorded by the mount and umount commands. The other options are incorrect because they do not display the mounted filesystems. The free command shows the amount of free and used memory in the system. The lsmounts command is not a standard Linux command. The cat /proc/filesystems command shows the filesystem types that are supported by the kernel. References:

[LPI Linux Essentials - 2.2 Mounting, Unmounting Filesystems]

How to get the complete and exact list of mounted filesystems in Linux? - Unix & Linux Stack Exchange

4 Commands to List Mounted File Systems in Linux - Linux Shell Tips

How To Show Mounted Devices In Linux Operating System

How to Check if a Filesystem is Mounted in Linux?

The sticky bit is a special permission bit that can be set for directories. It prevents users from deleting or renaming files in the directory that they do not own, even if they have write permission on the directory. This is useful for shared directories like /tmp, where users can create temporary files but not interfere with other users’ files12. The command chmod +t /tmp sets the sticky bit for the directory /tmp by adding the letter t to the end of the permission string. The command chmod 1775 /tmp also sets the sticky bit for the directory /tmp by adding the number 1 to the beginning of the octal mode. The number 1 represents the sticky bit in the octal notation34. The commands chmod +s /tmp, chmod 4775 /tmp, and chmod 2775 /tmp do not set the sticky bit, but rather the setuid or setgid bits, which are different special permission bits that affect how programs are executed5. References: 1: Sticky bit - Wikipedia 2: Linux Sticky Bit Concept Explained with Examples 3: chmod(1) - Linux man page 4: Understanding Linux File Permissions 5: Setuid and Setgid on Linux - GeeksforGeeks

The mount command is used to attach a filesystem to a directory on the system, which is called a mount point. The mount command requires the device name or the UUID of the filesystem as the first argument, and the mount point as the second argument. Optionally, the mount command can also take some options, such as the filesystem type, the mount options, and the label. The syntax of the mount command is:

mount [options] device mountpoint

In this question, the device name of the CD-ROM is /dev/sr0, and the mount point is /mnt/cdrom. Therefore, the correct command to mount the CD-ROM is:

mount /dev/sr0 /mnt/cdrom

This command will mount the CD-ROM as a read-only filesystem with the type iso9660, which is the standard format for optical discs. The mount command can automatically detect the filesystem type and the mount options, so there is no need to specify them explicitly. However, if you want to specify them, you can use the -t and -o options, respectively. For example, the following command is equivalent to the previous one:

mount -t iso9660 -o ro /dev/sr0 /mnt/cdrom

The other options are not correct because:

A. mount /dev/cdrom /mnt/cdrom: This command may work on some systems, but it is not guaranteed to be correct. The /dev/cdrom is usually a symbolic link to the actual device name of the CD-ROM, which can vary depending on the system. For example, on some systems, the /dev/cdrom may point to /dev/sr0, but on others, it may point to /dev/scd0 or /dev/hdc. Therefore, it is better to use the actual device name of the CD-ROM, which can be found by using the lsblk or the dmesg command.

C. mount -t cdrom /dev/sr0 /mnt/cdrom: This command is not valid because cdrom is not a valid filesystem type. The filesystem type for optical discs is iso9660, not cdrom. The mount command will fail with an error message saying:

mount: unknown filesystem type ‘cdrom’

D. mount -l cdrom /dev/sr0 /mnt/cdrom: This command is not valid because -l is not a valid option for the mount command. The -l option is used to list all the mounted filesystems, not to mount a filesystem. The mount command will fail with an error message saying:

mount: can’t find /dev/sr0 in /etc/fstab

E. mount -f /dev/sr0/mnt/cdrom: This command is not valid because it is missing a space between the device name and the mount point. The mount command requires two separate arguments for the device name and the mount point, separated by a space. Also, the -f option is used to fake the mount operation, not to perform the actual mount. The mount command will fail with an error message saying:

mount: /dev/sr0/mnt/cdrom: mount point does not exist.