Bash Shell Scripting: From Zero To Automation

Create your first bash script by adding a shebang (#!/bin/bash), make it executable with chmod +x, and run it as ./Hello to see it execute.

Learn to use bash if-else-elif constructs to test strings, emptiness with -z, and non-empty with -n. Practice interactive input and multi-branch actions for strings, numbers, and files.

Master bash if conditions for numbers and files. Learn integer comparisons and file tests, including existence, type, size, and negation, as well as permissions like readable and executable.

Explore bash logic conditions by combining tests with and (-a) and or (-o), check numbers within ranges, verify non empty and executable files, and use modern [[ ]] syntax.

Learn a practical bash scripting trick to jump up multiple directories with a single command. Showcase a bash script and three key parts of bash scripting for automation.

Use the source command to run a script in the current shell, updating variables and preserving the shell context, and note how dot notation, subshells, exit, and exec behave.

Use the type command to determine whether a command is an executable program, a shell built-in, or an alias, with examples like cat, cd, and ls.

Create and use bash aliases to shorten frequent commands, verify them with type, and make aliases permanent by adding them to your login script.

Use command substitution with $(command) to capture output, reuse it in scripts, and assign results to variables. Understand timing differences between live command output and static values, like date.

Explore how bash scripts accept and process parameters with $1, $2, and beyond, using braces for multi-digit indices, and count and iterate parameters with $# and $@/$* in loops.

Develop a back script that uses cd .. to ascend directories, addresses sub shell behavior, and leverages source with an alias to affect the current shell.

Add the script folder to the path, export it, and source your profile to run scripts anywhere in the terminal.

Every command has exit status, zero for success and non-zero for failure; view it with echo $?, grep shows 0 for matches, 1 for no matches, and >1 for errors.

Define and call shell functions to reuse code, pass inputs with positional parameters like $1 and $2, and use return values and exit statuses to signal success or failure.

Explore how variable scope works in bash functions, distinguishing global and local variables, and learn why using local keeps functions as black boxes.

Explore terminal computations, review basic arithmetic expressions, and learn the right environment for clear and advanced calculation toward the final script.

Explore the problems of bash arithmetic expansion, including lack of decimals and negative powers, and learn to use bc to perform accurate calculations inside scripts.

Master the bc environment to perform arithmetic, set scale for decimals, and use boolean expressions, powers, and square root. Use -l for math functions and -q for quiet mode.

Learn to redirect input with a here document, using a delimiter like AAA to feed content to cat and bc in scripts.

Learn how to redirect a command's input from a string using the here string, enabling commands like cat, bc, and read to read input without keyboard input.

Master the bash shift command to rotate positional parameters: $1 becomes $2, $2 becomes $3, and so on, with optional step counts and $0 providing the script’s absolute path.

Learn how to handle input and input redirection in bash by examining the internal field separator. Discover how to split elements or pass a single element.

Explore reading multiple variables in bash with the read command and here string redirection. Learn how to map values to A, B, C, D and handle extra input efficiently.

Learn to use the grep command to search text inside files, handle case sensitivity with -i, and combine grep with pipes and -v to filter results.

Learn how the internal field separator (IFS) governs bash read splitting, with examples using spaces and underscores, and how to temporarily change and restore IFS.

Learn to read complex Linux password files with Bash by using the IFS delimiter and redirection, and build a script to fetch a specific user's info from /etc/passwd.

Explore bash shell scripting: build a script to fetch user info from a password file via grep, parse with IFS and read, and handle not-found cases interactively.

Explore building a PATH script that inspects the PATH environment, lists directories, checks program presence with -c, shows locations of a command, and verifies if a folder is in PATH.

Develop a path script that lists each directory in PATH with a for loop, adjusting IFS, and verify command presence using -c and which while handling trailing slashes.

Create and run a bash script named max_string to read a file and identify the longest string contained in the file.

Learn how the pipe command chains the output of one command as input to another, with practical bash scripting examples like ls, tail, sort, and redirecting to files.

Learn how to use the wc command to count lines, words, and characters, understand newline effects, and apply -l, -w, and -m with pipes and simple folder counts.

Learn how the strings command extracts printable character sequences from a file, with a default minimum length of four, and how -n adjusts this threshold.

Develop a bash max string script that finds the longest word in a file by iterating words, computing lengths, and updating the reference word with input validation and built-in length.

Explore bash arrays: create, access, and modify one-dimensional arrays by index, loop through elements, append values, and count or unset elements for efficient scripting.

Learn to use the cut command to extract specific characters or fields from output, using -c and -b, ranges, and -F with -d/--delimiter.

Learn how the stat command reveals detailed file information on Linux, Unix, and Mac, including name, size, permissions, owner, group, and access times, with -c or --format.

Discover how the macOS stat command shows file metadata, produce readable output with -X, use format specifiers (percent N, U, G, S), and create aliases and portable scripts.

This lecture shows a portable bash script that counts file modification times in a directory using stat, tallies hourly occurrences with an array, and formats am/pm output.

Celebrate your progress by applying learned pieces to solve problems and create bash scripts, moving from zero to automation through topic focused lessons that cover wild cards and sub shells.