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

 This option to the find command is useful if the filenames contain spaces when redirecting the output of find to the xargs command. The syntax of the option is:

find [where to start searching from] [expression determines what to find] -print0

The -print0 option tells the find command to print the full file name on the standard output, followed by a null character (ASCII code 0) instead of the newline character. This allows file names that contain spaces or other special characters to be correctly interpreted by the xargs command, which can use the -0 option to read items from the standard input that are terminated by a null character. The syntax of the xargs command with the -0 option is:

xargs -0 [command]

The -0 option tells the xargs command to expect the items from the standard input to be separated by a null character, and to execute the command using the items as arguments.

Therefore, the command find … -print0 | xargs -0 … will search for files and directories using the find command, print the results with a null character as the separator, pipe the output to the xargs command, which will read the items with a null character as the separator, and execute another command using the items as arguments. This will avoid any problems with filenames that contain spaces or other special characters.

The other options are incorrect for the following reasons:

• A, -rep-space: This option does not exist in the find command. There is no option to replace spaces in the filenames with another character in the find command. The command will report an error and exit.
• B, -printnul: This option does not exist in the find command. There is a similar option, -print0, which prints the filenames with a null character as the separator, but -printnul is not a valid option. The command will report an error and exit.
• C, -nospace: This option does not exist in the find command. There is no option to ignore spaces in the filenames in the find command. The command will report an error and exit.
• D, -ignore-space: This option does not exist in the find command. There is no option to ignore spaces in the filenames in the find command. The command will report an error and exit.

References:

• How to Use the find Command in Linux - How-To Geek
• find command in Linux with examples - GeeksforGeeks
• find(1) - Linux manual page - man7.org
• [xargs command in Linux with examples - GeeksforGeeks]
• [How to Use the xargs Command on Linux - How-To Geek].

The command that uninstalls a package but keeps its configuration files in case the package is re-installed is dpkg -r pkgname. The dpkg command is the low-level tool for installing, building, removing, and managing Debian packages. The -r or --remove option removes an installed package from the system, but it does not delete the configuration files and other data that belong to the package. This way, if the package is re-installed later, the previous settings are preserved. The dpkg command is part of the 101.1 Determine and configure hardware settings topic of the LPI Linux Essentials certification program12.

The other options are either invalid or do not perform the desired task. The dpkg -s pkgname command shows the status of an installed package, but it does not uninstall it. The dpkg -L pkgname command lists the files that belong to an installed package, but it does not uninstall it. The dpkg -P pkgname command purges an installed or removed package, which means it deletes the configuration files and other data that belong to the package. The dpkg -v pkgname command shows the version of an installed package, but it does not uninstall it.

The ? symbol within regular expressions represents an optional match of the preceding qualifier. A qualifier is a character or a group of characters that can be repeated a certain number of times, such as , +, ?, {n}, {n,}, or {n,m}. The ? symbol means that the qualifier can occur zero or one times, but not more. For example, the regular expression colou?r matches both “color” and “colour”, but not “colouur” or “colr”. The ? symbol can also be used to make other qualifiers lazy, meaning that they will match the smallest possible number of characters, instead of the largest (greedy). For example, the regular expression a.?b matches the shortest string that starts with “a” and ends with “b”, such as “ab” or “a-b”, but not “a-b-c”. References:

• [LPI Exam 101 Detailed Objectives], Topic 103: GNU and Unix Commands, Objective 103.7: Perform basic file management, Weight: 4, Key Knowledge Areas: Use of egrep to search for extended regular expressions in text output.
• [Regular expression syntax cheat sheet], Topic: Quantifiers.

This command redirects the output of ls to standard error, which is file descriptor 2 by default. The syntax of the command is:

ls >& file_descriptor

The ls command is a utility that lists the files and directories in the current working directory or a specified directory. The >& symbol is a redirection operator that redirects the standard output of a command to another file descriptor, which can be a file, a device, or another stream. The file_descriptor is the number of the file descriptor to which the output is redirected.

Therefore, the command ls >&2 will run the ls command and redirect its output to file descriptor 2, which is standard error. This means that the output of ls will not be displayed on the screen, but sent to the standard error stream, which can be used for error handling or logging purposes.

The other commands are incorrect for the following reasons:

• A, ls >-1: This command will not redirect the output of ls to standard error, but it will cause an error. The > symbol is a redirection operator that redirects the standard output of a command to a file or device, overwriting any existing content. The -1 argument is not a valid file name or device name, and it will cause the shell to report an error and exit.
• B, ls <
• D, ls >>2: This command will not redirect the output of ls to standard error, but it will append the output of ls to a file named 2. The >> symbol is a redirection operator that redirects the standard output of a command to a file or device, appending to any existing content. The 2 argument is the name of the file to which the output is appended. If the file does not exist, it will be created. The command will not display anything on the screen, but write the output of ls to the file 2.
• E, ls |error: This command will not redirect the output of ls to standard error, but it will pipe the output of ls to another command named error. The | symbol is a pipe operator that redirects the standard output of one command to the standard input of another command. The error argument is the name of the command that receives the output of ls as its input. However, there is no such command named error in the Linux system, and the shell will report an error and exit.

The rmdir command removes an empty directory. To remove a directory whose name contains a backslash, the backslash must be escaped with another backslash. Therefore, the correct command is rmdir ~/\dir. The other commands will either fail to find the directory or interpret the backslash as part of a path name. References:

• [LPI Linux Essentials - 1.3 Basic Editing]
• [LPI Linux Essentials - 1.4 I/O Redirection]
• [LPI Linux Essentials - 1.5 Manage Simple Partitions and Filesystems]