LPI 101 - Comandos GNU/Linux 4- Marcus Vinicius Braga Alcantara

The command ":q!" in vi allows you to exit the file without saving any changes.

To read the contents of the variable PATH in the bash shell, you can use the command "echo $PATH". The "echo" command is used to display the value of a variable, and the "$" symbol is used to access the value of a variable. Therefore, "echo $PATH" will display the contents of the PATH variable in the bash shell.

The correct answer is "i". In vi, the "i" command is used to switch to insert mode, allowing the user to type and edit text using the keyboard.

A shell is a program that interprets user actions and commands in the operating system. It provides a command-line interface where users can interact with the system by typing commands. The shell takes these commands and executes them, allowing users to perform various tasks and control the system. Unlike utilities and applications, which are specific programs designed for particular functions, the shell acts as an intermediary between the user and the operating system, enabling them to access and manipulate system resources.

The correct answer is "echo $SHELL". This command will print the value of the SHELL environment variable, which typically contains the path to the current shell being used.

The question asks for the range of priority values for a process, which can vary from -20 to 19. The "+19" in the answer suggests that the priority value can also be positive, in addition to being negative or zero.

The command "echo "Hello World" | tr -d aieou" is using the "tr" command to delete all occurrences of the letters "a", "i", "e", "o", and "u" from the input string "Hello World". Therefore, the resulting output is "HllWrld".

The correct answer is "history." In the bash shell, the "history" command is used to view the command history. It displays a list of previously executed commands, along with their line numbers. This command is helpful for recalling and reusing past commands, saving time and effort.

To repeat the command number 3 in the command history, you would use "!3". This is a shorthand notation that allows you to quickly rerun a specific command without having to retype it.

Pressing the Esc key in vi switches from any other mode (such as insert or command mode) back to the normal mode.

The correct answer is "jobs". The "jobs" command is used to display all the jobs or tasks that are running in the background in the current shell session. It provides information such as the job ID and status of each task.

The correct answer is "foo && bar". This is because the "&&" operator in shell scripting means "AND". So, the command "foo && bar" will execute the command "foo" first, and only if it returns a status of 0 (indicating success), the command "bar" will be executed.

According to the FHS (Filesystem Hierarchy Standard), the man pages are typically found in the "/usr/share/man" directory. This directory is commonly used to store the system's documentation, including the manual pages. It is a standard location for man pages in most Linux distributions. Other directories mentioned in the options, such as "/opt/man", "/usr/doc/", "/var/pkg/man", and "/var/man", are not the standard locations for man pages as per the FHS.

The correct answer is "export set DISPLAY=:0:1; netscape". This command sets the display variable to ":0:1", which refers to the second monitor. By doing this, the program "netscape" will be displayed on the second monitor.

Separating the commands with a semicolon (;) allows you to execute multiple commands in a single line, saving time and effort. By pressing enter after entering the commands, each command will be executed sequentially. This method is quicker than typing each command individually and pressing enter after each one or creating a script to execute the commands.

This answer correctly creates a variable VAR1 with the value "fail" and exports it so that it can be accessed by a child bash process.

The command "history -c" is used to clear the entire command history. By running this command, all previously executed commands will be removed from the history file, effectively erasing the entire command history.

A regular user can assign a maximum nice value of 19 to a process during the execution of a new process. The nice value is used in Unix-like operating systems to prioritize the execution of processes. A lower nice value indicates a higher priority for the process. Regular users typically have limited privileges and cannot assign extremely high priority to processes, hence the maximum value they can assign is 19.

The variable "HOME" indicates the path to the user's home directory in the environment. This directory is typically the default location where the user's personal files and settings are stored.

The correct answer is "Ele vai quebrar o arquivo em novos arquivos de 1000 linhas." This means that the split command will divide the file into new files, with each file containing 1000 lines.

The correct answer is TERM(15) because the command "kill" by default sends a termination signal (SIGTERM) to a process. This signal instructs the process to gracefully terminate and clean up its resources before exiting. The other signals mentioned (HUP, QUIT, KILL) have different purposes, but they are not the default signal sent by the "kill" command.

O comando interno do bash chamado export é usado para definir variáveis de ambiente para aplicações. Isso significa que as variáveis definidas com o comando export estarão disponíveis para todos os processos que são executados a partir do shell atual. Isso é útil para configurar variáveis de ambiente que são necessárias para que um programa ou script funcione corretamente.

The correct answer is "cmd1 ; cmd2". The semicolon (;) is a command separator in the shell, which means that both cmd1 and cmd2 will be executed regardless of the exit status of cmd1. This allows for the sequential execution of multiple commands in the shell.

The command "dd" can be used to create a USB storage media from a disk image. "dd" is a command-line utility in Unix-like operating systems that is used to convert and copy files. In this case, it can be used to create a bootable USB drive by copying the disk image onto the USB drive bit by bit.

Metacharacters are special control characters used in regular expressions. They have special meaning and are used to define patterns and match specific characters or groups of characters in a string.

As per the given options, the variables PS1 and PS2 are described as the normal prompt and extended prompt. This means that these variables control the appearance and behavior of the command prompt in a Unix-like operating system. The PS1 variable defines the prompt displayed when waiting for a new command, while the PS2 variable defines the prompt displayed when a command is continued onto the next line.

The correct answer is "kill -TERM 123". The "-TERM" option sends a termination signal to the process with PID 123, allowing it to clean up any resources before exiting. The other options, "-PIPE", "-KILL", and "-STOP", send different signals that do not provide the process with the opportunity to clean up before termination.

The correct answer is PS1="\h: \w>". This command sets the prompt in the .profile file to display the hostname (\h) and the current working directory (\w). This will help the user easily identify the server they are connected to.

The command "yy" in vi will copy the current line into the vi buffer.

The correct answer is "-maxdepth". This option is used in the command "find" to restrict the search to a specific number of subdirectories. By specifying a number after "-maxdepth", the command will only search for files or directories within that number of levels deep from the starting directory.

The correct answer is "PATH". The PATH environment variable stores a list of directories that the shell uses to search for executable files. When a command is entered in the shell, it checks each directory in the PATH variable in order to find the corresponding executable file. This allows users to run commands without specifying the full file path.

When the -v option is used with the grep command, it inverts the matching to select non-matching lines. In other words, it will display all the lines that do not contain the specified pattern or expression. This can be useful when you want to exclude certain lines from the output.

The correct answer is "sed -e "s/list/LIST/" myfile.txt". This command uses the sed utility to search for the word "list" in the file myfile.txt and replace all occurrences with "LIST". The -e option specifies the script to be executed, and "s/" is the substitute command in sed.

After issuing the "vi" command without any additional parameters, it starts in command mode and opens a new empty file.

The correct answer is "TEST="FOO"". This is the correct command to define a variable called TEST with the content FOO. The other options either use incorrect syntax or do not follow the correct format for defining a variable.

The combination of the "/" key and the "Enter" key allows the user to continue typing on a new line below the current line.

The correct answer is "cat file1.txt | grep -i foo". This command will use the "cat" command to display the contents of "file1.txt" and then pipe it to the "grep" command with the "-i" flag, which will perform a case-insensitive search for the string "foo".

After deleting 3 lines of text in vi and moving the cursor to a different line, the "p" command (lowercase) will insert the deleted content below the current line.

In the normal mode of the vi editor, the "?" command can be used to initiate a reverse search for text. This command allows the user to search for a specific text pattern in the backward direction from the current cursor position.

The correct answer states that grep -F or fgrep should be used when the text being searched does not contain any regular expression patterns. This means that if the search does not require any complex pattern matching, using grep -F or fgrep can be more efficient and faster than using regular grep. These commands are specifically designed for simple string matching without the need for regular expressions.

O comando "file" determina o tipo de um arquivo usando um arquivo de banco de dados de definição que contém informações sobre todos os tipos de arquivos comuns.

The command "myapp | tee file1.log" will send the output of the program "myapp" to both the standard output (stdout) and the file "file1.log".

The correct answer is DISPLAY. The DISPLAY variable is used to specify the remote machine and display number where X applications should be displayed. It is commonly used in Unix-like operating systems to enable X11 forwarding, allowing users to run graphical applications on a remote machine and have them displayed on their local machine.

The command !! in the bash shell is used to execute the previous command. Similarly, Ctrl-P is a keyboard shortcut that is used to navigate to the previous command in the command history. Therefore, executing Ctrl-P and Enter will have the same effect as executing !!, which is to run the previous command.

The "set" command is used to alter the options and positional parameters for a running bash. It allows the user to change various settings and configurations within the bash environment.

The answer is "Esc-b, Del". Pressing the Esc key followed by the b key will move the cursor back one word. Then, pressing the Del key will delete the space between the slash and the word "hadden" without having to retype the whole command.

When the combination of keys CTRL+C is pressed on the keyboard, the signal SIGINT is sent to a process. This signal is used to interrupt the process and request it to terminate gracefully. It allows the process to clean up resources and perform any necessary actions before exiting.

The command "more" can help deal with the problem of extra characters being displayed on the screen when reading the man pages. The "more" command allows the user to view the output one page at a time, pausing after each page, which helps in managing the excessive characters and makes it easier to read the content.

The correct answer is "Comando ou Programa". When you type a command, it is the command or program itself that is responsible for checking the syntax and providing an error message if it is incorrect. The shell, operating system, and kernel are all components of the system that facilitate the execution of the command, but they are not directly responsible for generating the error message.

The correct answer is that the cut command cannot reorder fields. This means that it can only select the output based on the position of the fields and cannot rearrange them in a different order.