ShellScriptingBasicsCheatSheet.md

Shell Scripting Basics Cheat Sheet

1. Define a shebang (specify the interpreter)

#!/bin/bash

2. Print a message to the terminal

echo "Hello, World!"

3. Define a variable

my_var="Hello"

4. Access a variable (use $ symbol)

echo $my_var

5. Simple if statement

if [ condition ]; then
    # Commands if condition is true
    echo "Condition is true"
fi

6. If-else statement

if [ condition ]; then
    echo "Condition is true"
else
    echo "Condition is false"
fi

7. For loop

for i in {1..5}; do
    echo "Iteration $i"
done

8. While loop

count=1
while [ $count -le 5 ]; do
    echo "Count: $count"
    ((count++))
done

9. Read input from user

read -p "Enter your name: " name
echo "Hello, $name!"

10. Define a function

my_function() {
    echo "This is a function!"
}

11. Call a function

my_function

12. Pass arguments to a script

# Access arguments with $1, $2, etc.
echo "First argument: $1"
echo "Second argument: $2"

13. Check for file existence

if [ -f "filename.txt" ]; then
    echo "File exists"
else
    echo "File does not exist"
fi

14. Logical AND

if [ condition1 ] && [ condition2 ]; then
    echo "Both conditions are true"
fi

15. Logical OR

if [ condition1 ] || [ condition2 ]; then
    echo "At least one condition is true"
fi

16. Case statement (switch-like structure)

case "$variable" in
    "value1") echo "Value is 1";;
    "value2") echo "Value is 2";;
    *) echo "Default case";;
esac

17. Exit a script with a status code

exit 0

18. Redirect output to a file

echo "Output to file" > output.txt

19. Append output to a file

echo "Append to file" >> output.txt

20. Chain commands (execute command1, then command2)

command1 && command2 # Executes command2 only if command1 succeeds
command1 || command2 # Executes command2 only if command1 fails