case MacOS Command Guide
The case command in MacOS is a powerful tool for performing conditional branching in shell scripts. It allows you to check the value of a variable and execute different commands based on the value. With the case command, you can create more complex and versatile scripts, making it a valuable addition to your scripting toolbox. In this guide, you’ll learn the syntax of the case command, how to use it with different options, and explore practical examples to demonstrate its usage in real-world scenarios. Mastering the case command can help you automate tasks, handle different scenarios, and improve the efficiency of your shell scripts on MacOS.
case Syntax:
command [option] [parameter]Options:
| Option | Description |
|---|---|
| -a | Lists all entries including ones starting with a dot (.) |
| -l | Lists in long format |
| -h | Prints sizes in a human-readable format |
| -t | Sorts by modification time |
Parameters:
| Parameter | Description |
|---|---|
| directory | Specifies the directory to list |
| file | Specifies the file to display information |
case Command Samples:
Check the Operating System Version
case $(uname) in "Darwin") echo "MacOS" ;; *) echo "Not MacOS" ;;esacCheck the Day of the Week
day=$(date +%u)case $day in 1) echo "Monday" ;; 2) echo "Tuesday" ;; 3) echo "Wednesday" ;; 4) echo "Thursday" ;; 5) echo "Friday" ;; 6) echo "Saturday" ;; 7) echo "Sunday" ;;esacCheck the File Type
file_type=$(file /path/to/file)case $file_type in *"text"*) echo "Text file" ;; *"image"*) echo "Image file" ;; *"directory"*) echo "Directory" ;; *) echo "Unknown file type" ;;esacCheck if a Number is Even or Odd
read -p "Enter a number: " numif (( num % 2 == 0 )); then echo "$num is even"else echo "$num is odd"fiCheck the User’s Permission Level
user=$(whoami)case $user in "root") echo "Superuser" ;; "admin") echo "Administrator" ;; *) echo "Regular user" ;;esacCheck the Season Based on the Month
month=$(date +%m)case $month in 12|1|2) echo "Winter" ;; 3|4|5) echo "Spring" ;; 6|7|8) echo "Summer" ;; 9|10|11) echo "Autumn" ;; *) echo "Unknown season" ;;esacCheck the Exit Status of a Command
ls /non/existent/directorycase $? in 0) echo "Command executed successfully" ;; 1) echo "Error: Missing arguments" ;; 2) echo "Error: File not found" ;;esacHow do I use case in MacOS?
To use the case command in MacOS, execute the following command:
case $variable in pattern1) # actions for pattern1 ;; pattern2) # actions for pattern2 ;; *) # default case ;;esacHow can I match multiple patterns in a case statement in MacOS?
To match multiple patterns in a case statement in MacOS, you can use the vertical bar ”|” to separate the patterns within a single parentheses group. Here is an example:
case $variable in pattern1|pattern2) # actions for pattern1 or pattern2 ;; pattern3) # actions for pattern3 ;; *) # default case ;;esacHow can I make my case statement in MacOS case-insensitive?
To make your case statement in MacOS case-insensitive, you can use the “shopt” command to set the “nocasematch” option before executing the case statement. Here is an example:
shopt -s nocasematchcase $variable in pattern1) # actions for pattern1 ;; pattern2) # actions for pattern2 ;; *) # default case ;;esacHow do I perform pattern substitution in a case statement in MacOS?
To perform pattern substitution in a case statement in MacOS, you can utilize parameter expansion within the case statement itself. Here is an example:
case ${variable/match/replace} in pattern1) # actions for pattern1 ;; pattern2) # actions for pattern2 ;; *) # default case ;;esacHow can I use regular expressions in a case statement in MacOS?
To use regular expressions in a case statement in MacOS, you can leverage the “extended regular expression” operator ”=~” along with the “if” statement to achieve pattern matching with regex. Here is an example:
if [[ $variable =~ pattern ]]; then # actions if the variable matches the pattern using regexelse # actions if the variable does not match the patternfiApplications of the case command
- Conditional execution in shell scripts
- Providing a cleaner and more readable alternative to nested if statements
- Implementing multi-way branching in shell scripts