Master shell scripting fundamentals on Mac and Linux terminals

📜 **Creating and Running Scripts** - Understanding shell scripts and the shebang line (#!/bin/bash) - Making scripts executable with chmod +x - Running scripts with ./script.sh or bash script.sh - Creating and using variables (NAME='John', echo $NAME) - Command substitution with $(command) and backticks - Storing command output in variables - Understanding variable expansion and quoting 🔀 **Conditional Statements** - Basic if statement syntax: if [ condition ]; then ... fi - File tests: -f (file exists), -d (directory exists), -e (exists) - String comparisons: == (equal), != (not equal) - Numeric comparisons: -eq, -ne, -lt, -gt, -le, -ge - If-else statements for alternative branches - Elif (else-if) for multiple conditions - Logical operators: && (AND), || (OR) - Testing conditions with the test command - Practical examples for file and directory checks 🔄 **Loops: for and while** - For loop syntax: for variable in list; do ... done - Iterating over lists of words - Brace expansion: {1..10} for sequences - C-style for loop: for ((i=1; i=10; i++)) - While loop: while [ condition ]; do ... done - Using break to exit loops early - Using continue to skip iterations - Looping through files with wildcards (*.sh) - Incrementing counters in loops - Practical examples for automation **Commands Covered:** - #!/bin/bash - Shebang line - chmod +x script.sh - Make script executable - ./script.sh - Run executable script - bash script.sh - Run script with bash - NAME='value' - Create variable - $NAME - Use variable - $(command) - Command substitution - `command` - Command substitution (older syntax) - if [ condition ]; then ... fi - If statement - if [ -f file ]; then ... - Check if file exists - if [ -d dir ]; then ... - Check if directory exists - [ "$VAR" == "value" ] - String comparison - [ $NUM -lt 10 ] - Numeric comparison - for i in {1..5}; do ... done - For loop with range - for ((i=1; i=5; i++)); do ... done - C-style for loop - while [ condition ]; do ... done - While loop - break - Exit loop early - continue - Skip to next iteration **Perfect for:** - Mac and Linux terminal users ready to automate tasks - Developers learning shell scripting fundamentals - System administrators creating automation scripts - Anyone wanting to learn bash scripting basics - Users looking to create custom commands - Beginners starting their shell scripting journey