case

case value in
    pattern1) cmds1;;
    pattern2) cmds2;;
    .
    .
    .
esac

Execute the first set of commands (cmds1) if value matches pattern1, execute the second set of commands (cmds2) if value matches pattern2, etc. Be sure the last command in each set ends with ;;. value is typically a positional parameter or other shell variable. cmds are typically Unix commands, shell programming commands, or variable assignments. Patterns can use file-generation metacharacters. Multiple patterns (separated by |) can be specified on the same line; in this case, the associated cmds are executed whenever value matches any of these patterns. See the Examples here and under eval.

Korn Shell Notes

• The Korn shell allows pattern to be preceded by an optional open parenthesis, as in (pattern). It's useful for balancing parentheses inside a $( ) construct.

• The Korn shell also allows a case to end with ;& instead of ;;. In such cases control "falls through" to the group of statements for the next pattern.

Examples

Check first command-line argument and take appropriate action:

case $1 in     # Match the first arg
    no|yes) response=1;;
    -[tT])  table=TRUE;;
    *)      echo "unknown option"; exit 1;;
esac

Read user-supplied lines until user exits:

while :        # Null command; always true
do
   echo "Type . to finish ==> \c"
   read line
   case "$line" in
      .) echo "Message done"
         break ;;
      *) echo "$line" >> $message ;;
   esac
done