Linux Bash Shell Scripting: Complete Guide (incl. AWK & SED)

Learn what a script is: a sequence of commands stored in a file, with loops and arguments, and how to create, set permissions, and run it in the terminal.

Learn to craft robust shell scripts by understanding the shebang, choosing /bin/bash interpreters, setting executable permissions, and ensuring cross-machine compatibility.

Explore Bash string comparison with single and double brackets, quoting, and space sensitivity, learning how to test for equal or not equal and identify root user status.

loop through all script arguments using for arg in "$@" to handle each argument separately, and contrast with "$*" that joins all arguments.

Build a bash script that mimics cat with line numbers, accepting one file argument, printing each line with a number, and reporting if the file doesn't exist.

Explore using getopts to parse positional parameters A and B with required arguments and C and D without arguments, demonstrating case statements and automatic dash handling in bash scripts.

Learn how awk reports the number of fields per line using NF, indices like $F, and arithmetic to display or compute field counts in space-delimited input.

Use the print command to display lines that match a pattern, suppress default printing with -n, and apply ranges and the last line reference for precise file output.

Learn how to use sed to append or prepend text to specific lines, match lines by a pattern, insert before lines, and add text at the first line.

Explore sed's substitute command, using s/old/new/ to replace text, apply line ranges (1,$), perform in-place edits with -i, and reuse the matched text with &.

Explore a sed-based script that reads files line by line, detects leading or trailing spaces and tabs, and prints clean lines while exiting on issues.

Learn how to tidy sed scripts by fixing trailing space issues, control newline output with echo, and add conditional messages with a green background to indicate fixes.