Newly Released LPI 101-500 Exam PDF

The PATH variable defines the directories in which a Bash shell searches for executable commands. The PATH variable is a colon-separated list of directories that the shell scans when a command is entered. For example, if the PATH variable is set to /usr/local/bin:/usr/bin:/bin, then the shell will look for the command in these three directories, in order. If the command is not found in any of these directories, the shell will report an error message. The other options are either invalid or do not perform the desired task. The BASHEXEC, EXECPATH and PATHRC variables are not valid Bash variables. The BASHRC variable is used to specify a file that is executed whenever a new interactive shell is started, but it does not affect the command search path. References:

• LPIC-1 Exam 101 Objectives, Topic 103: GNU and Unix Commands, 103.1 Work on the command line
• LPIC-1 Linux Administrator 101-500 Exam FAQ, LPIC-1 Exam 101 Objectives, GNU and Unix Commands (Total Weight: 25)

The shell redirection that will write standard output and standard error output to a file named filename is >filename 2>&1. This command uses the following syntax:

• filename: Redirects standard output (file descriptor 1) to a file named filename. If the file does not exist, it will be created. If the file exists, it will be overwritten.
• 2>&1: Redirects standard error (file descriptor 2) to the same destination as standard output. The & symbol indicates that the following number is a file descriptor, not a filename.

The order of the redirections is important, as they are processed from left to right. If the order was reversed, as in 2>&1 >filename, the command would not work as expected, because it would first redirect standard error to the current standard output (which is the terminal by default), and then redirect standard output to the file, leaving standard error unchanged.

The other commands are incorrect for the following reasons:

• A. 2>&1 >filename: This command will redirect standard error to the current standard output, and then redirect standard output to the file, leaving standard error unchanged.
• C. 1>&2>filename: This command will redirect standard output to the current standard error, and then redirect standard error to the file, leaving standard output unchanged.
• D. >>filename: This command will only redirect standard output to the file in append mode, without affecting standard error.
• E. 1&2>filename: This command is not valid, as it is missing the > symbol before the first file descriptor, and it will produce an error message.

References:

• [LPI Exam 101 Detailed Objectives], Topic 103: GNU and Unix Commands, Objective 103.4: Use streams, pipes and redirects, Weight: 4, Key Knowledge Areas: Redirecting standard input, standard output and standard error.
• How to redirect and append both standard output and standard error to a file with Bash, Topic: Substituting Text.

∗∗Thegrepcommandthatwillprintonlythelinesthatdonotendwitha/inthefilefooisgrep−v′/’ foo. This command uses the following options and pattern:

-v: Inverts the matching, meaning that it only outputs the lines that do not match the pattern. /:Matchesa/characterattheendofaline.The symbol represents the end of a line in regular expressions. foo: The name of the file to search.

The output of this command will show all the lines in the file foo that do not have a / as the last character. For example, if the file foo contains the following lines:

/home/user/ /var/log/messages /etc/passwd /usr/bin/

The output of the command will be:

/var/log/messages /etc/passwd

The other commands are incorrect for the following reasons:

• grep ‘/$’ foo: This command will print only the lines that do end with a / in the file foo, which is the opposite of what is required.
• grep ‘/#’ foo: This command will print only the lines that contain the string /# in the file foo, which is not related to the question.
• grep -v ‘/#’ foo: This command will print only the lines that do not contain the string /# in the file foo, which is also not related to the question.

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 ofegrepto search for extended regular expressions in text output.
• [How to Use the grep Command on Linux], Topic: Start and End of Lines.

The command that will copy the current line into the vi buffer is yy. The yy command is a shorthand for yank yank, which means to yank (copy) the current line. The vi buffer is a temporary storage area where thecopied text is stored until it is pasted somewhere else. The yy command can also be preceded by a number to indicate how many lines to copy. For example, the command 3yy will copy the current line and the next two lines into the buffer.

The other commands are incorrect for the following reasons:

• A. c: This command is a shorthand for change, which means to delete the text specified by the following motion and enter insert mode. For example, the command cw will delete the current word and allow the user to type a new one.
• B. cc: This command is a shorthand for change change, which means to delete the current line and enter insert mode. This command is similar to dd followed by i, but it is faster and more convenient.
• C. 1c: This command is not valid, as it is missing a motion after the change command. The motion specifies what text to delete and replace. For example, the command 1cw will delete one word and enter insert mode.
• E. 1y: This command is also not valid, as it is missing a motion after the yank command. The motion specifies what text to copy into the buffer. For example, the command 1yw will copy one word into the buffer.

References:

• [LPI Exam 101 Detailed Objectives], Topic 103: GNU and Unix Commands, Objective 103.8: Perform basic file editing operations using vi, Weight: 3, Key Knowledge Areas: Navigate a document using vi.
• Vi Cheat Sheet, Topic: Basic vi commands.