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

 The command that replaces each occurrence of ‘bob’ in the file letter with ‘Bob’ and writes the result to the file newletter is sed ‘s/bob/Bob/g’ letter > newletter. This command uses the following options and syntax:

• s: Specifies the substitution operation.
• /: Separates the pattern and the replacement strings.
• bob: The pattern to be searched and replaced.
• Bob: The replacement string.
• g: The global flag that indicates all occurrences of the pattern in each line should be replaced, not just the first one.
• letter: The name of the input file.
• : Redirects the output to a file.
• newletter: The name of the output file.

The output of this command will be a new file called newletter that contains the same text as letter, except that every ‘bob’ is replaced by ‘Bob’. For example, if the file letter contains the following text:

Dear bob, I hope this letter finds you well. I am writing to inform you that your subscription to our magazine has expired. If you wish to renew it, please send us a check for $50 by the end of this month. Otherwise, we will have to cancel your subscription and remove you from our mailing list. Thank you for your cooperation and support. Sincerely, Alice

The file newletter will contain the following text:

Dear Bob, I hope this letter finds you well. I am writing to inform you that your subscription to our magazine has expired. If you wish to renew it, please send us a check for $50 by the end of this month. Otherwise, we will have to cancel your subscription and remove you from our mailing list. Thank you for your cooperation and support. Sincerely, Alice

The other commands are incorrect for the following reasons:

• A. sed ‘/bob/Bob’ letter > newletter: This command is missing the s option and the second / delimiter, and will produce an error message.
• B. sed s/bob/Bob/ letter < newletter: This command is using the wrong redirection operator (< instead of >), and will try to read the input from newletter instead of letter, and write the output to the standard output instead of newletter.
• C. sed’s/bob/Bob’ letter > newletter: This command is missing a space between sed and the first ', and will produce an error message.
• E. sed ‘s/bob, Bob/’ letter > newletter: This command is using a comma (,) instead of a slash (/) as a delimiter, and will produce an error message.

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 sed to edit files in place.
• How to Use the sed Command on Linux, Topic: Substituting Text.

The command that will reduce all consecutive spaces down to a single space is tr -s ’ ’ < a.txt > b.txt. This command uses the following options and syntax:

• -s: Squeezes repeated characters listed in the first set with single occurrence.
• ’ ': Specifies a space character as the first set.
• < a.txt: Redirects the input from a file named a.txt.
• b.txt: Redirects the output to a file named b.txt.

The output of this command will be a new file called b.txt that contains the same text as a.txt, except that any sequence of multiple spaces will be replaced by a single space. For example, if the file a.txt contains the following text:

This is a text file with multiple spaces.

The file b.txt will contain the following text:

This is a text file with multiple spaces.

The other commands are incorrect for the following reasons:

• A. tr ‘\s’ ’ ’ < a.txt > b.txt: This command will replace every whitespace character (\s) with a space character, which will not reduce the number of spaces, but rather convert tabs and newlines into spaces.
• B. tr -c ’ ’ < a.txt > b.txt: This command will complement the first set, meaning that it will apply the operation to all characters that are not spaces. This will not affect the spaces at all, but rather squeeze all other characters.
• C. tr -d ’ ’ < a.txt > b.txt: This command will delete all spaces from the input, which will not reduce them to a single space, but rather remove them completely.
• D. tr -r ’ ’ ‘\n’ < a.txt > b.txt: This command will replace all spaces with newlines, which will not reduce the spaces, but rather create a new line for each word.

References:

• [LPI Exam 101 Detailed Objectives], Topic 103: GNU and Unix Commands, Objective 103.2: Process text streams using filters, Weight: 3, Key Knowledge Areas: Use of tr to translate characters or to squeeze and/or delete them.
• Tr Command in Linux with Examples, Topic: How to squeeze a sequence of repetitive characters using -s option.

The swapoff command is used to disable swapping on a device or a file. It takes the path of the device or file as an argument, or -a to disable all swaps. Disabling swap can improve the performance of the system if there is enough physical memory, or it can be necessary if the swap size needs to be changed. However, disabling swap can also cause problems if the system runs out of memory and has no swap space to use. References:

• How to Disable Swap in Linux - Linux Handbook
• How to Permanently Disable Swap in Linux? - GeeksforGeeks
• LPI Linux Essentials - 1.1 Operating System Basics

The cut command is used to extract sections from each line of a file or input stream. The -d option specifies the delimiter that separates the fields in each line. The -f option specifies the fields to select. In this case, the delimiter is a colon (:) and the fields are 1 and 7. The first field is the user name and the seventh field is the login shell. Therefore, the cut command with these options will generate a list of user names and their login shells from /etc/passwd. References:

• Linux cut Command Explained with 6 Examples
• How to Use the Linux cut Command
• cut command in Linux with examples

The SIGINT signal is sent to a process when the user presses the key combination CTRL+C on the keyboard. This signal is used to interrupt the process and cause it to terminate, unless the process catches or ignores the signal. The SIGTERM signal is the default signal sent by the kill command to request a process to terminate gracefully. The SIGSTOP signal is used to pause a process and make it stop executing until it receives a SIGCONT signal. The SIGKILL signal is used to force a process to terminate immediately and cannot be caught or ignored by the process. References:

• LPIC-1 Exam 101 Objectives, Topic 103: GNU and Unix Commands, 103.2 Process management
• LPIC-1 Linux Administrator 101-500 Exam FAQ, LPIC-1 Exam 101 Objectives, GNU and Unix Commands (Total Weight: 25)

The command dd can be used to create a USB storage media from a disk image. The command dd is a low-level utility that can copy and convert data from one source to another, such as files, devices, or pipes. It can be used to create a bootable USB drive from an ISO image or a raw disk image. The syntax is: dd if=input of=output [options]. For example, to create a USB storage media from a disk image file named linux.img, the command would be:

dd if=linux.img of=/dev/sdb

This will copy the contents of linux.img to the device /dev/sdb, which is assumed to be the USB drive. The device name may vary depending on the system, so it is important to check the correct device name beforerunning the command. The command dd can also accept various options, such as bs to specify the block size, status to show the progress, or conv to apply conversions to the data. For example, to create a USB storage media from an ISO image file named linux.iso, with a block size of 4 MB and a progress indicator, the command would be:

dd if=linux.iso of=/dev/sdb bs=4M status=progress

The command dd is also known as "disk destroyer" because it can overwrite data without warning or confirmation. Therefore, it is advisable to use it with caution and backup any important data before using it. The other options are not correct because:

• gdisk is a command to create and manipulate GUID partition tables (GPT), but it does not create a USB storage media from a disk image1.
• cc is a command to compile C programs, but it does not create a USB storage media from a disk image2.
• fdisk is a command to create and manipulate DOS partition tables, but it does not create a USB storage media from a disk image3.
• mount is a command to mount file systems, but it does not create a USB storage media from a disk image4. References:
• How to Create a Bootable Linux USB Flash Drive, the Easy Way
• dd(1) — Linux manual page
• How to use the dd command in Linux - TechRepublic
• LPI Exam 101 Detailed Objectives, section 1.101.3

 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 i and a commands are two of the most commonly used commands in the vi editor to enter the insert mode. The insert mode allows the user to insert text into the file. The difference between the i and a commands is that the i command inserts text before the current cursor position, while the a command inserts text after the cursor position. For example, if the cursor is on the letter “e” in the word “editor”, then pressing i will allow the user to insert text before the “e”, while pressing a will allow the user to insert text after the “e”. The user can exit the insert mode by pressing the Esc key, which will return to the command mode. References:

• Basic vi commands (cheat sheet)
• VI Editor with Commands in Linux/Unix Tutorial
• How to use Vi editor in Linux (with examples)