Loops

In Bash, we have for and while loops

For Loops

For loops iterate through a set of values until the list is exhausted: 很像python (or python 像bash...)

for variable in list do stuff here done

#!/bin/sh
for i in 1 2 3 4 5
do
  echo "Looping ... number $i"
done

While Loops

while [Boolean Expression] do stuff here done

#!/bin/sh
INPUT_STRING=hello
while [ "$INPUT_STRING" != "bye" ]
do
  echo "Please type something in (bye to quit)"
  read INPUT_STRING
  echo "You typed: $INPUT_STRING"
done

Branch

基本的if...then...else... :

if [ ... ]
then
  # if-code
else
  # else-code
fi

如果你喜欢elseif:

if  [ something ]; then
 echo "Something"
 elif [ something_else ]; then
   echo "Something else"
 else
   echo "None of the above"
fi

Case:

#!/bin/sh

echo "Please talk to me ..."
while :
do
  read INPUT_STRING
  case $INPUT_STRING in
    hello)
        echo "Hello yourself!"
        ;;
    bye)
        echo "See you again!"
        break
        ;;
    *)
        echo "Sorry, I don't understand"
        ;;
  esac
done
echo

Example: read myfile line by line and processing with while and case:

#!/bin/sh
while read f
do
  case $f in
    hello)        echo English    ;;
    howdy)        echo American    ;;
    gday)        echo Australian    ;;
    bonjour)    echo French    ;;
    "guten tag")    echo German    ;;
    *)        echo Unknown Language: $f
        ;;
   esac
done < myfile****