shell script - constructs－逗點大的雨滴

if...else...fi

num1=1
num11="1"

num2=2
num22="2"

#if...else...fi
echo "if...else...fi"
echo
   #value
   if [ $num1 -eq $num11 ]; then
   echo "int equal"
   else
   echo "int not equal"
   fi
   echo

   #string
   if [ ${num11} == ${num22} ]; then
   echo "str equal"
   else
   echo "str not equal"
   fi
   echo

for...done

#for...done
echo "for...done"
echo
   #string
   for animal in dog cat elephant
   do
   echo "there are ${animal}s";
   done
   echo

   #value
   for val in 1 2 3
   do
   echo `expr 2 \* $val`
   done

   #value2
   s=0
   for (( i=1; i<=2; i=i+1 ))
   do
   s=$(($s+$i))
   done
   echo "The result of '1+2+3+...+$nu' is ==> $s"

while...do....done

#while...do...done
echo "while...do...done"
wh_val=5
while [ $wh_val -ne 0 ];
do
echo "$wh_val"
wh_val=`expr $wh_val - 1`
done

case...esac

#case ..... esac
ary_fruit=("Apple" "Banana" "Guava")
for loc in 0 1 2
do
   case ${ary_fruit[$loc]} in
   "Apple")
   echo this fruit is ${ary_fruit[$loc]}
   ;;
   "Banana")
   echo this fruit is ${ary_fruit[$loc]}
   ;;
   "Guava")
   echo this fruit is ${ary_fruit[$loc]}
   ;;
   esac
done

result

steven@ATM64:~/base_shell$ sh constructs.sh
if...else...fi

int equal

str not equal

for...done

there are dogs
there are cats
there are elephants

2
4
6
The result of '1+2+3+...+' is ==> 3
while...do...done
5
4
3
2
1