LPI 101-500 - LPIC-1 Exam 101, Part 1 of 2, version 5.0

 The ext3 and ext2 filesystems preallocate a fixed number of inodes at the filesystem’s make/creation time and do not generate them as needed. This means that the number of inodes in these filesystems is determined by the size of the partition and the inode ratio, which is usually 16 KB per inode. The inode ratio can be specified when creating the filesystem with the mke2fs command. The number of inodes in these filesystems cannot be changed dynamically, unless the filesystem is reformatted. This can lead to inode exhaustion, which occurs when all the available inodes are used up, even if there is still free disk space. To avoid this problem, it is advisable to estimate the number of files and directories that will be stored on the filesystem and adjust the inode ratio accordingly. The other options are incorrect because they do not preallocate a fixed number of inodes at the filesystem’s make/creation time. The JFS and XFS filesystems use dynamic inode allocation, which means that they create inodes as needed, depending on the file and directory creation. The procfs filesystem is a virtual filesystem that does not store any data on the disk, but provides information about the processes and the kernel. Therefore, it does not have any inodes.

For more information on how inodes work and how to manage them, you can refer to the following articles:

Inodes in Linux: limit, usage and helpful commands | Stackscale

filesystems - What is an inode? - Unix & Linux Stack Exchange

Allocation Methods | Linux.org

 The renice command changes the nice level of a running process. The nice level is a value that affects the scheduling priority of a process. A lower nice level means a higher priority and a higher nice level means a lower priority. The renice command requires the process ID (PID) of the target process and the new nice level as arguments. For example, renice -n 10 1234 will change the nice level of the process with PID 1234 to 10. References: LPI Exam 101 Detailed Objectives, Topic 103: GNU and Unix Commands, Weight: 25, Objective 103.3: Perform basic file management, renice command

SysVinit is a program for Linux and Unix-based systems that initializes the system and spawns all other processes. It runs as a daemon and has PID 1. The boot loader starts the kernel and the kernel starts SysVinit. A Linux or Unix based system can be started up into various runlevels, which are modes of operation that define what services and processes are running. The /etc/inittab file is the configuration file for SysVinit, which defines the default runlevel, the available runlevels, and the actions to be taken when entering or leaving a runlevel.

The telinit command is used to change the current runlevel of the system or to send a signal to SysVinit. The telinit command takes a single argument, which can be either a runlevel number (0-6) or a special character. The syntax of the telinit command is:

telinit [runlevel|character]

The runlevel argument instructs SysVinit to switch to the specified runlevel. For example, to switch to runlevel 3, which is the multi-user mode with networking, use the following command:

telinit 3

The character argument instructs SysVinit to perform a special action. For example, to reboot the system, use the following command:

telinit 6

The q character argument instructs SysVinit to reload its configuration file, /etc/inittab, without changing the current runlevel. This is useful when the /etc/inittab file has been modified and the changes need to be applied. For example, to reload the /etc/inittab file, use the following command:

telinit q

The other options are not correct because:

A. reinit: This command does not exist in the Linux system. There is no such command as reinit in the Linux documentation or the man pages.

B. initreload: This command does not exist in the Linux system. There is no such command as initreload in the Linux documentation or the man pages.

C. telinit 7: This command is not valid because 7 is not a valid runlevel number. The valid runlevel numbers are 0-6, where 0 means halt, 1 means single-user mode, 2 means multi-user mode without networking, 3 means multi-user mode with networking, 4 means user-defined, 5 means graphical mode, and 6 means reboot. If you run this command, you will get an error message saying:

telinit: invalid runlevel: 7

E. init reinit: This command is not valid because reinit is not a valid argument for the init command. The init command is a synonym for the telinit command, and it takes the same arguments as the telinit command. The valid arguments for the init command are either a runlevel number (0-6) or a special character. If you run this command, you will get an error message saying:

init: invalid runlevel: reinit

This output will be displayed when the user fred executes the following command:

echo 'fred $USER'

The echo command is a built-in Linux feature that prints out arguments as the standard output. The syntax of the echo command is:

echo [option] [string]

The option can modify the behavior of the echo command, such as enabling the interpretation of escape characters or omitting the newline after the output. The string is the text that is displayed as the output.

The single quotation marks (’ ') are used to enclose the string argument and prevent any expansion or substitution of the characters inside the quotation marks. This means that any variables, commands, or special characters inside the single quotation marks are treated as literal characters, not as expressions.

The $USER variable is a shell variable that holds the username of the current user. However, since it is enclosed in single quotation marks, it is not expanded to its value, but printed as it is.

Therefore, the command echo ‘fred $USER’ will print the string fred $USER as the output, without any changes. The output will be the same for any user who executes the command, not just fred.

The other outputs are incorrect for the following reasons:

A, fred fred: This output would be displayed if the $USER variable was expanded to its value, which is fred for the user fred. However, since the $USER variable is enclosed in single quotation marks, it is not expanded, but printed as it is.

B, fred /home/fred/: This output would be displayed if the $USER variable was expanded to its value, which is fred for the user fred, and then concatenated with the string /home/ to form a path. However, since the $USER variable is enclosed in single quotation marks, it is not expanded, but printed as it is. Also, there is no concatenation operator in the echo command, so the string /home/ would not be added to the output.

C, ‘fred $USER’: This output would be displayed if the single quotation marks were also printed as part of the output. However, the single quotation marks are not part of the string argument, but only used to enclose it and prevent any expansion or substitution. They are not displayed as the output.

E, ‘fred fred’: This output would be displayed if the single quotation marks were also printed as part of the output, and the $USER variable was expanded to its value, which is fred for the user fred. However, neither of these conditions are true. The single quotation marks are not part of the string argument, but only used to enclose it and prevent any expansion or substitution. They are not displayed as the output. The $USER variable is enclosed in single quotation marks, so it is not expanded, but printed as it is.

The correct answer is C, 2dd. This command will delete two lines, the current and the following line, in vi editor. The syntax of the command is:

[number]dd

The number specifies how many lines to delete, starting from the current line. The dd command deletes the lines and puts them in a buffer, which can be pasted later with the p command. If no number is given, the command will delete only the current line.

The other commands are incorrect for the following reasons:

A, d2: This command will delete two characters, not two lines. The syntax of the command is:

d[motion]

The motion specifies how many characters to delete, starting from the current cursor position. The 2 motion means two characters to the right. The d command deletes the characters and puts them in a buffer, which can be pasted later with the p command.

B, 2d: This command is incomplete and will not work. The d command requires a motion argument to specify how many characters to delete. The 2 argument is only a number, not a motion. The command will wait for another keystroke to complete the motion.

D, dd2: This command will delete the current line and then move the cursor two lines down. The syntax of the command is:

dd[number]

The dd command deletes the current line and puts it in a buffer, which can be pasted later with the p command. The number specifies how many lines to move the cursor down, after deleting the current line. If no number is given, the command will move the cursor to the next line.

E, de12: This command will delete from the current cursor position to the end of the word, and then move the cursor to the 12th line. The syntax of the command is:

d[motion][number]

The d command deletes the characters specified by the motion and puts them in a buffer, which can be pasted later with the p command. The e motion means the end of the word. The number specifies the line number to move the cursor to, after deleting the characters.

 The find command is used to search for files and directories that match certain criteria. The -uid option specifies the numeric user ID of the owner of the file or directory, while the -user option specifies the name of the owner. The -print option prints the full file name of the matching file or directory to the standard output. Therefore, both find /tmp -uid root -print and find /tmp -user root -print will print all files and directories within the /tmp directory or its subdirectories which are also owned by the user root. The other options are either invalid or do not perform the desired task. The -path option matches the whole path name, not just the starting directory. The -print option is implied if no other action is specified, but it is good practice to include it for clarity. References:

LPIC-1 Exam 101 Objectives, Topic 103: GNU and Unix Commands, 103.4 Use streams, pipes and redirects

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

The world-writable directory that should be placed on a separate partition in order to prevent users from being able to fill up the / filesystem is /tmp. This directory is used by applications and users to store temporary files, and it is world-writable by default. By creating a separate partition for /tmp, the amount of space available to users is limited, and the root filesystem is protected from being filled up by temporary files1.

To create a separate partition for /tmp, you can use the fdisk or parted command to create a new partition on the disk. Once the partition is created, you can format it with a filesystem such as ext4, and then mount it to the /tmp directory using the mount command. Finally, you can modify the /etc/fstab file to ensure that the partition is mounted automatically at boot time1. Here is an example of the steps to create a separate partition for /tmp:

After completing these steps, the /tmp directory will be mounted on a separate partition, and users will be limited in the amount of space they can use for temporary files.

 The command that updates the linker cache of shared libraries is ldconfig. This command creates, updates, and removes the necessary links and cache for the run-time linker, ld.so, to the most recent shared libraries found in the specified directories. To add a new library directory to the cache, you need to edit the /etc/ld.so.conf file and rerun ldconfig. You can use the -p option to print the current cache contents1.

The other commands are either invalid or unrelated to the linker cache. mkcache, soconfig, and mkldconfig are not standard Linux commands. lddconfig is a typo for ldd, which is a command that prints the shared libraries required by a program2.