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

The stream redirection operators within Bash are used to redirect the input and output of commands to files, devices, or other commands. The valid stream redirection operators within Bash are:

• < : This operator redirects the standard input (STDIN) of a command from a file or device. For example, wc -l < file.txt counts the number of lines in file.txt by using it as the input for the wc command.
• > : This operator redirects the standard output (STDOUT) of a command to a file or device, overwriting any existing content. For example, echo "Hello World" > file.txt writes the string “Hello World” to file.txt, replacing any previous content.
• >> : This operator redirects the standard output (STDOUT) of a command to a file or device, appending to any existing content. For example, echo "Hello World" >> file.txt writes the string “Hello World” to file.txt, without deleting any previous content.
• >& : This operator redirects one file descriptor to another file descriptor. A file descriptor is a number that represents an open file or device. The standard input (STDIN) has the file descriptor 0, the standard output (STDOUT) has the file descriptor 1, and the standard error (STDERR) has the file descriptor 2. For example, command > file 2>&1 redirects both the standard output and standard error of the command to the file.
• <& : This operator redirects one file descriptor from another file descriptor. For example, command <&3 redirects the standard input of the command from the file descriptor 3.

The other operators are not valid stream redirection operators within Bash. They will cause syntax errors or unexpected behavior. For example, #> is a comment followed by a redirection operator, %> is a modulo operator followed by a redirection operator, and >>> is a bitwise right shift operator followed by a redirection operator.

References:

• Redirections (Bash Reference Manual)
• Guide to Stream Redirections in Linux | Baeldung on Linux
• Standard Streams in Bash | Delft Stack
• Bash Tutorial => Redirection
• stream redirection order and what os perform in details

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.

References:

• vi/vim delete commands and examples | alvinalexander.com
• How to Delete Lines in Vim / Vi | Linuxize
• How can I delete multiple lines in vi? - Stack Overflow

The command ls > files uses the output redirection operator > to send the output of the ls command to a file named files. If the file does not exist, it will be created and will contain the output of the ls command, which is the list of files and directories in the current working directory. This is explained in the first web search result 1 and the second web search result 2. References: 1: Input Output & Error Redirection in Linux [Beginner’s Guide] 2: Redirections (Bash Reference Manual)

The program that runs a command in specific intervals and refreshes the display of the program’s output is watch. This command is used to run any designated command at regular intervals and displays the output of the command on the terminal window. It is useful when you have to execute a command repeatedly and watch the command output change over time. The syntax of the watch command is:

watch [options] command

The options can modify the behavior of the watch command, such as how to format the output, how to handle signals, or how to enable color. The command is the command that you want to run and monitor. The default interval between each execution of the command is 2 seconds, but you can change it with the -n or --interval option. For more help using the watch command and its options, run man watch or visit this link.

This command will run dbmaint in the background and make it immune to hangup signals, which means it will continue to run even when the user logs out of the system. The nohup command prefixes the command with nohup, which intercepts the SIGHUP signal that is sent to the process when the terminal sessionends. The output of the command is redirected to a file called nohup.out by default, unless specified otherwise. The & symbol puts the command in the background, allowing the user to run other commands in the same shell.

The other commands are incorrect for the following reasons:

• A, job -b dbmaint: This command is invalid and will not work. There is no job command in Linux, and the -b option is not a valid option for any command. The command that is used to list the background jobs in the current shell session is jobs, and it does not have a -b option either.
• B, dbmaint &>/dev/pts/null: This command will run dbmaint in the background, but it will not prevent it from being terminated when the user logs out of the system. The &> symbol redirects both the standard output and standard error of the command to a file or device, in this case /dev/pts/null. However, this device does not exist, and the redirection will fail. Even if the device was /dev/null, which is a special device that discards any output sent to it, the command would still be susceptible to hangup signals and would not survive the logout.
• D, bg dbmaint: This command will not run dbmaint in the background, but it will try to resume a stopped background job with the name dbmaint. The bg command is used to move a stopped foreground process to the background and continue its execution. However, if there is no such process with the name dbmaint, the command will fail. Even if there was such a process, it would still be terminated when the user logs out of the system, unless it was disowned or prefixed with nohup.
• E, wait dbmaint: This command will not run dbmaint in the background, but it will wait for a background process with the name dbmaint to finish and return its exit status. The wait command is used to pause the execution of the current shell until one or more background processes complete. However, if there is no such process with the name dbmaint, the command will fail. Even if there was such a process, it would still be terminated when the user logs out of the system, unless it was disowned or prefixed with nohup.

References:

• How to Run Linux Commands in Background | Linuxize
• How to Run Linux Commands in Background | phoenixNAP KB
• How to Run Linux Commands in the Background - MUO
• How to Run Linux Commands in Background & Bring Them Back

The command that prints a list of usernames (first column) and their primary group (fourth column) from the /etc/passwd file is cut -d : -f 1,4 /etc/passwd. The cut command is used to extract selected fields or characters from each line of a file or standard input. The -d or --delimiter option specifies the character that separates the fields, which in this case is a colon (:). The -f or --fields option specifies the fields to be printed, which in this case are the first and the fourth fields. The /etc/passwd file is a text file that contains information about the user accounts on the system, such as the username, password, user ID, group ID, home directory, and login shell. The first column of the file is the username and the fourth column is the group ID, which corresponds to the primary group of the user. The cut command will print these two columns separated by a colon for each line of the file. For example, running cut -d : -f 1,4 /etc/passwd will produce an output like this:

root:0 daemon:1 bin:1 sys:3 sync:4 games:5 man:12 lp:7 mail:8 news:9 uucp:10 proxy:13 www-data:33 backup:34 list:38 irc:39 gnats:41 nobody:65534 systemd-network:100 systemd-resolve:101 syslog:102 messagebus:103 _apt:104 lxd:105 uuidd:106 dnsmasq:107 sshd:108 pollinate:109 vboxadd:999 ubuntu:1000

The other commands are either invalid or do not perform the desired task. The fmt command is used to reformat paragraphs of text, but it does not have a -f option. The sort command is used to sort lines of text, but it does not have a -t option. The paste command is used to merge lines of files, but it does not have a -f option. The split command is used to split a file into pieces, but it does not have a -c option. References:

• Linux Essentials - Linux Professional Institute Certification Programs
• Exam 101 Objectives - Linux Professional Institute
• cut(1) - Linux manual page
• /etc/passwd file - Linux.com

The command chmod g+s sales sets the setgid bit on the directory sales, which means that any new file or subdirectory created within sales will inherit the group ownership of the directory. The command chmod 2775 sales does the same thing, but also sets the permissions of the directory to rwxrwxr-x, whichmeans that the owner, group, and others can read, write, and execute files in the directory. Both commands ensure that new files created within the directory sales are owned by the group sales. The other commands are either invalid or do not affect the group ownership of new files. References:

• Linux Essentials - Linux Professional Institute Certification Programs1
• Exam 101 Objectives - Linux Professional Institute

The umask value is a four-digit octal number that determines the default permissions for new files and directories created by a user. The umask value specifies the permissions that are not granted to the user, group, and others. The permissions are represented by three bits for each category, where 1 means execute, 2 means write, and 4 means read. The sum of these values indicates the combination of permissions. For example, 7 means read, write, and execute; 6 means read and write; 5 means read and execute; 4 means read only; 3 means write and execute; 2 means write only; 1 means execute only; and 0 means no permission.

The umask value is subtracted from the maximum permissions for files and directories, which are 666 and 777, respectively. The maximum permissions are then converted to binary and bitwise ANDed with the bitwise complement of the umask value. The result is the default permissions for the new files and directories. For example, if the umask value is 0027, the default permissions for a new file are:

666 - 027 = 639 639 in octal = 110 011 001 in binary 027 in octal = 000 010 111 in binary Bitwise complement of 027 = 111 101 000 in binary 110 011 001 AND 111 101 000 = 110 001 000 in binary 110 001 000 in binary = 608 in octal 608 in octal = rw- — —

The default permissions for a new directory are:

777 - 027 = 750 750 in octal = 111 101 000 in binary 027 in octal = 000 010 111 in binary Bitwise complement of 027 = 111 101 000 in binary 111 101 000 AND 111 101 000 = 111 101 000 in binary 111 101 000 in binary = 750 in octal 750 in octal = rwx r-x —

Therefore, the umask value of 0027 ensures that new files can be read and written by their owning user, and are not accessible at all for everyone else. New directories can be read, written and listed by their owning user, read and listed by their owning group, and are not accessible at all for everyone else.

References:

• Umask command in Linux with examples - GeeksforGeeks
• What Is umask in Linux, and How Do You Use It? - How-To Geek
• What is UMASK and how to set UMASK in Linux/Unix? - Kernel Talks