Bash Scripting and Shell Programming for the Linux Command

Learn how the pwd command prints the current directory and its absolute path, with a hands-on example showing how to run pwd and view the result.

Learn that ls command is the most common command to list directory contents, identify where files or directories are located, and view files in the current directory excluding hidden files.

Learn to list all files, including hidden ones, with ls -a, revealing dot files like dot cache and dot replit, and use ls -l to display permissions, size, and timestamps.

Create directories in the Linux file system using the mkdir command, illustrated with a practical example that creates a test directory and lists its contents.

learn how the cd command changes your current directory and navigates the directory tree, using pwd and ls to verify your location.

Learn how to navigate directories with Bash commands, using cd, cd .., and pwd to move between test and script directories and verify location.

Learn how the echo command prints text to the console, displays variable values for debugging, and is used in shell scripts and batch files.

Learn how the touch command creates empty files and updates timestamps, with a hands-on example creating hello.txt and verifying its size using ls -l.

Use the touch command with the -c option to update the timestamp of an existing file; if the file does not exist, no action occurs.

Learn how the cat command reads, creates, and concatenates files, uses redirection to create sample.txt, and displays line numbers with cat -n.

Learn how the clear command clears all previous commands and outputs from the console, and how to use it by typing clear and pressing enter.

Use the history command to view a list of previously executed commands, providing quick access to your past inputs.

Learn how the cp command copies files or directories within the file system, demonstrated by copying sample.txt into the test folder and verifying with ls -l.

Create a new directory with mkdir, explore it with ls -l, navigate with cd, and copy a directory into it using cp -r, then verify with ls -l.

Learn how to use the move command to relocate files and directories, with a practical example moving hello.txt into a test folder using cd, ls, and a destination path.

Learn to use the rm command to delete files and directories, with and without prompts, including using absolute paths, verifying with ls -l, and employing -i for confirmation.

Execute rm -r to delete a non-empty directory and its contents, verify with ls and pwd, and navigate folders to confirm removal.

Set folder permissions with chmod to grant read, write, and execute access for everyone (777), demonstrated on a test folder and verified with ls -l.

Use the find command to locate files and directories and run additional bash commands on matches, including searching for temp.txt with -name and verifying results with pwd and ls -l.

Use the find command to search for files matching a specific pattern inside a script, employing double quotes and an asterisk dot search, and verify that only main.dot is found.

Execute an interactive bash delete sequence that prompts for confirmation to delete a file like sample.txt and uses -i for case-insensitive search, then verify with ls -l.

Learn how to use grep to search for patterns in files, perform case sensitive and case insensitive searches with -i, and view lines containing matched text with practical examples.

Learn how the sleep command suspends a bash script for a specified number of seconds to create a delay, demonstrated between hello there and bye.

Terminate a process using the kill command by supplying its PID, as shown with ps output. Explore user-oriented and non-terminal process options with -U and -x.

See how the hash character marks comments in Bash, stopping execution of lines starting with #, with an example where echo prints and commented lines remain ignored.

Learn how to use the command separator in Bash to run two or more commands on a single line by placing a semicolon between commands, and see the outputs.

Use redirect operator (>) to send a command's output to a file, creating it if missing and overwriting it if exists. The echo example writes to temp.txt to illustrate overwrite.

Master bash redirection by directing command output and errors to a file, including redirecting errors to temp.txt with ampersand. Learn how to suppress command output by sending it to /dev/null.

Learn how to append command output to a file in Bash using the >> redirection operator, avoiding overwrites and verifying results with practical echo examples.

Explore how to use the input redirect character in Bash to feed command input from a file, with a practical example using cat and temp.txt.

The pipe (|) passes output from one command to the next, enabling command chaining. Cat temp.txt | grep working.

Learn how to escape special characters in bash by using a backslash before the character, preventing the command separator from splitting two echo commands on the same line.

Master how the tilde in bash navigates to the home directory and how to combine it with paths, using cd and pwd to verify locations.

Discover how the period is a special character representing the current directory in bash, and learn to run a script from the current directory using period slash your script.

Master using the double dot to navigate to the parent directory in bash, by running cd .. and verifying with pwd to move up one level.

Explore bash variables and untyped data handling, and learn how bash assigns values without explicit data types. Print values with echo using dollar signs to display number and str values.

Learn how Bash scripts receive runtime input via command line arguments, using $0 for the script name, $1 and $2 for arguments, and $# to count them.

Learn how to assign one variable's value to another in bash, define variables like STR and STR one, use $STR to reference them, and echo to display results in console.

Demonstrate that bash shell variables are case sensitive, with uppercase and lowercase names referring to different variables; printing an undeclared uppercase variable prints nothing while a lowercase variable prints hello.

Avoid whitespace on either side of the equals sign between a variable name and its value in bash. This lesson demonstrates error and shows a working script that prints hello.

Learn to read user input in bash using the read command, store it in a variable, and print the value with echo to display on the console.

Learn to prompt users for input with read -p, assign the input to a variable, and display the value using echo.

Learn to hide user input in bash by using -p and -s together, run the script, and see the username stay invisible until enter is pressed and then echoed.

Explore debugging bash scripts with set -x to print each line and enable debugging for the whole script or sections, then verify a swap using read, echo, and variables.

Learn to debug bash scripts from the command line using bash -x, compare with the set command, and observe a trace of each line after expansion but before execution.

Use the echo command to debug Bash scripts by printing variable values, as shown with num3 equaling 15, demonstrating how to check and simplify debugging without extra set commands.

Learn bash if statements for decision making by evaluating a user input and executing code when the condition is true, including a ten-check example with read.

Pass command line arguments into an if condition using the first argument as $1; run ./main.sh 10 to print value is same, and 11 to show no output.

Learn how bash variables are case sensitive and how case changes can cause unary operator expected errors in if conditions. Understand that the binary operator requires two arguments for comparisons.

Demonstrate how to use the if-else condition in bash by evaluating a condition and executing the appropriate block, printing 'value is same' or 'value is not same' with echo.

Learn how to use nested if conditions in Bash to validate multiple inputs and print a message when both conditions are true.

Explore how nested if else statements drive decision making in bash by selecting code blocks based on conditions, illustrated with a sample where values either match or do not.

Explore the elseif (elif) condition in bash to handle multiple conditions within an if-else statement, demonstrated with a numeric variable and echoing values like 10 and 11.

Learn to use the Bash test command to check file and directory existence with -f and -d, and handle an if condition to print 'file found' or 'file not found'.

Learn to check if a test folder exists in bash by listing with ls -l, and print 'folder found' or 'folder not found' as the script runs.

Learn how to check if a bash variable exists using a double-bracket if condition with -v, illustrated by defining A=100 and printing variable exists or variable does not exist.

Learn how the bash case statement mirrors a switch, testing a value against patterns with the pipe operator and using esac to close, with an asterisk as the default.

Learn to read user input with the read command, use a bash case statement for Apple and Nokia patterns, and display the result with echo via a default branch.

Learn how to create strings in bash, assign them to variables, check the length of the string, concatenate strings, and print results with echo.

Check whether a given string is empty using the -z parameter. Read input into str, then use an if condition to echo 'string is empty' or 'string is not empty'.

Learn how Bash handles string length without a built-in function, by using the hash symbol and ${#var} to measure length, store it, and verify the result.

Explore how to extract a substring from a string in Bash by defining a variable, using ${str:0:10} to pull characters from index zero, and echoing the result.

Learn how to extract substrings in bash by taking characters after a specified delimiter or space, count characters, remove unwanted parts, and retrieve all characters after a given position.

Extract a single character from a string by counting indices and selecting a length of one. Display the character at index eight and print T to the console.

Learn how to extract a specific character from the end of a string using substring operations in Bash, including counting characters and printing results in the console.

learn how to concatenate strings in bash by defining variables like str and str1 and combining them without extra operators, then print hello there to the console.

Learn to concatenate strings in Bash by using double quotes and placing both inside, then execute the script to print 'Hello there from the Bash world' on the console.

Explore Bash shell operators, including arithmetic, relational, and logical operators, and learn how these symbols manipulate operands to perform mathematical and logical actions in scripts.

Explore arithmetic operators in Bash shell, including addition, subtraction, multiplication, division, exponential, and modulus, with a hands-on example using double brackets to compute 5 plus 3 equals 8.

Explore bash arithmetic operators by performing subtraction and multiplication, using minus and asterisk, and print results 2 and 15 to the console.

Master bash assignment operators, including the addition assignment operator, to update variables such as num. Verify results with echo to print the updated value.

Demonstrate multiplication and division assignment operators in Bash by replacing plus with asterisk and using division, showing outputs of 25 and 1 on the console.

Master relational operators in bash, including equal to, not equal to, greater than, greater than equal to, less than, and less than equal to, and apply them in if conditions.

Demonstrates the less-than relational operator in bash using if-else logic to compare numbers. It shows how the script prints 'value is smaller' or 'value is greater' depending on the comparison.

Explore bash logical operators for testing conditions and building complex expressions, using and, or, not with double brackets to combine conditions and drive true or false outcomes in scripts.

Learn how the logical or operator in bash shell combines two conditions so the if statement is true when at least one condition is true, with examples.

Explore the logical not operator in bash, learning how it inverts true and false to control if and else blocks, producing 'worked' or 'failed' messages in scripts.

Explore how the for loop and while loop conditionally perform a command several times, iterating over strings, numbers, or array elements, using do and done.

Explore the for loop in bash by declaring a variable, listing items 1 through 5, and printing each value as the loop iterates.

Learn to read a range in a Bash for loop by specifying start, stop, and increment, with a default increment of one from 1 to 10 and printing each i.

Demonstrates using a bash for loop to read a range with a custom increment via double dot syntax, and prints the sequence 1, 3, 5, 7, 9.

Declare an array in bash, iterate through its elements with a for loop using ${array[@]}, and print the values to the console.

Explore how the break statement terminates a for loop in bash, using an if condition to break when I equals three, and print 1 and 2 to the console.

Learn how the continue statement controls a Bash for loop by skipping specific iterations and moving to the next one, demonstrated by printing numbers 1 to 4 on the console.

Demonstrates a Bash while loop with a double-bracket condition, initializing num=2 and num1=8, printing each value, and incrementing num with +=1 until it reaches eight, producing 2 through 7.

Explore the bash until loop, which executes a command as long as the condition is false and is evaluated before each execution, stopping when it becomes true.

Learn how bash arrays can hold strings and numbers, defined inside brackets with space-separated items and no comma, and initialized with an assignment operator to create your first bash array.

Access array elements in bash using square brackets and the index, starting from zero. Echo the value at index 1 to print 2, illustrating element retrieval in arrays.

Explore accessing array elements in Bash by using * and @ to expand all items, and observe how echo prints the entire array to the console.

Iterate over an array in bash with a for loop, using ${array[@]} to assign each element to a variable and print it, resulting in 1, 2, 3, 4.

Learn to print the index values of a Bash array by prefixing the array name with an exclamation mark, and print indices to the console.

Learn how to count the number of elements in a Bash array using the hash character, and print the array length (four) to the console.

Add an element to a bash array by specifying its index, then print the array to verify the new element at that index.

Update an element of a Bash array by specifying its index, such as changing the value at index one from two to six, then verify by executing.

Delete an element from a bash array by using the unset command with its index, and follow a practical example that removes the element at index 1.