101-500 Exam Results

The -v option for the egrep command activates the invert matching mode, which means that it only outputs the lines that do not match the given pattern or regular expression. This is useful for filtering out unwanted lines or finding exceptions in a file. For example, the following command will output all the lines in the file my_text that do not contain the word “Linux”:

egrep -v Linux my_text

The -v option can be combined with other options to modify the output format or behavior of the egrep command. For example, the -c option will count the number of non-matching lines instead of printing them, and the -i option will ignore the case of the pattern while matching. 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.

[Linux egrep Command with Examples], Topic: Invert Matching with egrep.

The character that, added to the end of a command, runs that command in the background as a child process of the current shell is the ampersand symbol (&). This means that the command will not block the shell and the user can enter other commands while the background command is running. The background command will also not receive any input from the keyboard or the terminal. The shell will print the job number and the process ID of the background command, and the user can use the jobs command to list the status of all background jobs in the current shell session. To bring a background job to the foreground, the user can use the fg command with the job number or the process ID. To terminate a background job, the user can use the kill command with the process ID.

The other characters are not valid or relevant for running a command in the background. The exclamation mark (!) is used to access the command history or to negate a condition. The plus sign (+) is used for arithmetic operations or to append text. The percent sign (%) is used for arithmetic operations or to refer to a job number. The hash sign (#) is used for comments or to specify a hexadecimal number.

According to the Filesystem Hierarchy Standard (FHS), the directory /usr/share/man contains manual pages for user commands, system calls, library functions, and other documentation1. The other directories are either non-standard, deprecated, or used for different purposes. For example, /opt/man is used for manual pages for add-on application software packages1, /usr/doc/ is an old location for documentation files that is no longer used2, /var/pkg/man and /var/man are not defined by the FHS. References:

[LPI Linux Essentials - 1.6 Basic File Editing]

[LPI Linux Essentials - 1.7 Personalize and/or Localize Your Linux System]

[LPI Linux Essentials - 1.8 Basic Security and File Permissions]

The p command in vi inserts the content of the buffer below the current line. The buffer is where the deleted or yanked text is stored temporarily. The P command inserts the buffer above the current line. The i command enters the insert mode before the cursor position. The U command restores the current line to its original state. The u command undoes the last change made to the file. 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]