Basic Navigation and File Management

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Questions and Answers

What does the command 'chmod 755 [file]' do?

Makes the file writable for all users

Changes the owner of the file

Adds read permission to the file only

Sets specific permissions for the owner, group, and others (correct)

Which command would you use to terminate a process with a specific process ID?

top

kill [pid] (correct)

htop

What is the purpose of the '>'' operator in command line operations?

To append output to a file

To display the permissions of a file

To redirect output to a file, overwriting its content (correct)

To list all processes

Which command can you use to view all running processes with more details?

ps aux Signup and view all the answers

When using the 'new' operator in C++, what does it do?

It allocates dynamic memory for a variable Signup and view all the answers

What does the command 'kill -9 [pid]' accomplish?

Forcibly terminates a process Signup and view all the answers

How can you append output to an existing file?

By using the command 'echo Hello >> myfile.txt' Signup and view all the answers

Which of the following can dynamically allocate memory for an array in C++?

int* arr = new int[10]; Signup and view all the answers

What is the purpose of the 'pwd' command in Linux?

Displays the current directory path Signup and view all the answers

Which command would you use to remove a directory and its contents in Linux?

rm -r [directory] Signup and view all the answers

Which command can you use to view the first 10 lines of a file called 'data.txt'?

head -n 10 data.txt Signup and view all the answers

What can you infer about the command 'grep -i '[pattern]' [file]'?

It performs a case-insensitive search for the pattern Signup and view all the answers

How do you create a new directory named 'Projects' using the command line?

mkdir Projects Signup and view all the answers

In which situation would you use the 'less [file]' command?

To view large files without editing Signup and view all the answers

Which command would you use to copy a file called 'example.txt' to a directory named 'backup'?

cp example.txt backup/ Signup and view all the answers

What does the command 'ls -a' accomplish in a directory?

Lists all files including hidden files Signup and view all the answers

Study Notes

pwd Displays the current working directory path.
ls Lists the files and directories within the current directory.
ls -l Shows detailed information about each file and directory, including permissions, size, and modification date.
ls -a Includes hidden files in the listing.
cd [directory] Changes the current working directory to the specified directory.
cd .. Moves up one level in the directory hierarchy, to the parent directory.
mkdir [directory] Creates a new directory with the specified name.
rmdir [directory] Removes an empty directory.
touch [file] Creates an empty file or updates the timestamp of an existing file.
rm [file] Deletes a file.
rm -r [directory] Recursively deletes a directory and all of its contents.
cp [source] [destination] Copies a file or directory to a new location.
mv [source] [destination] Moves or renames a file or directory.

Viewing and Editing Files

cat [file] Displays the entire contents of a file.
head -n [number] [file] Displays the first [number] lines of a file.
tail -n [number] [file] Displays the last [number] lines of a file.
nano [file] Opens a file in the nano text editor, allowing editing in the terminal.
vim [file] Opens a file in the vim text editor, a more advanced editor.
less [file] Opens a file for viewing and simple navigation without editing, useful for large files.

Searching and Finding Files

find [path] -name [filename] Searches for files with a specific name within a specified path. For example, find . -name "example.txt" searches the current directory and its subdirectories for a file named "example.txt".
grep '[pattern]' [file] Searches for lines within a file that contain a specific pattern.
grep -r '[pattern]' [directory] Recursively searches for lines containing a specific pattern within all files in a directory and its subdirectories.
grep -i '[pattern]' [file] Performs a case-insensitive search for a pattern.
grep -n '[pattern]' [file] Displays the line numbers along with the lines that match the pattern.

Permissions and File Ownership

chmod [options] [file] Changes the permissions of a file.
chmod 755 [file] Sets permissions for:
- owner: read, write, and execute
- group: read and execute
- other: read and execute
chmod +x [file] Adds execute permission to a file.
chown [user]:[group] [file] Changes the ownership of a file to a specified user and group. For example, chown user1:group1 myfile.txt

Working with Processes

ps Lists currently running processes.
ps aux Provides a more detailed listing of all processes, including usernames and CPU usage.
top Displays a real-time view of system processes and resource usage.
kill [pid] Terminates a process with the specified process ID (PID).
kill -9 [pid] Forcibly terminates a process by its PID.
& Runs a command in the background, allowing the terminal to continue accepting commands while the command runs. For example, ./myprogram &

File Redirection and Piping

> Redirects the output of a command to a file, overwriting any existing content. For example, ls > output.txt writes the output of the ls command to the file "output.txt".
>> Appends the output of a command to a file, preserving existing content. For example, echo "More text" >> output.txt appends the string "More text" to "output.txt".
| Pipes the output of one command as input to another command. For example, ls | grep ".cpp" lists only those files ending in ".cpp".

Dynamic Memory, Pointers, and Arrays in C++

new and delete allocate and deallocate dynamic memory in C++.
- int* arr = new int; allocates memory for one integer.
- delete[] arr; deallocates the memory.
Pointers in C++ represent memory addresses. -* is the dereference operator, which accesses the value at a pointer's address. -& is the address-of operator, which returns the memory address of a variable.
Arrays with Pointers - can use pointers to create arrays and access elements.

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Description

Test your understanding of basic file management and navigation commands in a command line interface. This quiz covers essential commands like pwd, ls, cd, and more. Perfect for beginners looking to improve their command-line skills.