bash case - ghdrako/doc_snipets GitHub Wiki

CASE Statement

The case statement is used for multi-way branching based on the value of an expression.

case <variable> in
 <pattern 1>)
   <code to execute if expression matches pattern1>
   ;;
 <pattern 2>)
   <code to execute if expression matches pattern2>
   ;;
 )
   <code to execute if none of the patterns match>
  ;;
esac
case "$Variable" in
    #List patterns for the conditions you want to meet
    0) echo "There is a zero.";;
    1) echo "There is a one.";;
    *) echo "It is not null.";;
esac
read -p "How many shoes do you have?"
case value in
  0|1)
    echo "Not enough shoes! You can't walk"
    ;;
  2)
    echo "Awesome! Go walk!"
    #...
    ;;
  *)
    echo "You got more shoes than you need"
    #...
    ;;
esac
space_free=$( df -h | awk '{ print $5 }' | sort -n | tail -n 1 | sed 's/%//' )

case $space_free in
  [1-5]*)
     echo Plenty of disk space available
     ;;
  [6-7]*)
     echo There could be a problem in the near future
     ;;
   8*)
     echo Maybe we should look at clearing out old files
     ;;
   9*)
     echo We could have a serious problem on our hands soon
     ;;
   *)
     echo Something is not quite right here
     ;;
esac
case $CIRCLE_BRANCH in
    "develop")
        export ENVIRONMENT="dev"
        export HEROKU_APP=dev-app
        ;;
    "staging")
        export ENVIRONMENT="staging"
        export HEROKU_APP=staging-app
        ;;
    "production")
        export ENVIRONMENT="production"
        export HEROKU_APP=production-app
        ;;
esac
file_to_process="report.pdf"
case "$file_to_process" in
*.txt)
echo "Processing a text file..."
;;
*.pdf)
echo "Converting PDF to text..."
pdftotext "$file_to_process"
;;
*.zip)
echo "Extracting archive..."
unzip "$file_to_process"
;;
*)
echo "Unknown file type!"
;;
esac

Multiple Matches per Pattern

Using the ‘or’ operator (|) lets you combine patterns under a single case branch:

case "$response" in
yes | y | YES | Yes)
echo "Affirmative!"
;;
n | no | NO)
echo "Negative!"
;;
*)
echo "Please enter yes or no."
;;
esac

Nested Case Statements

case "$1" in
  start)
    case "$2" in
      production)
        run_production_server
        ;;
      test)
        run_test_server
        ;;
      *)
        echo "Specify environment ('production' or 'test')"
        ;;
    esac
    ;;
# More primary options....
esac
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