1 #!/bin/bash
2 #if test2
3 echo -n "Enter your name: "
4 read NAME
5 if [ "$NAME" == "" ]
6 then
7 echo "You dont't enter any word "
8 fi
2、關于if/elif/else的應用
if後邊跟的條件必須用[ ](中括号)括起來然後下邊用then,elif後邊跟的條件也必須用[ ](中括号)括起來然後下邊用then,然後用else最後用if。
1 #!/bin/sh
2 echo "Please input a number year :"
3 read year
4 let "n1=$year%4"
5 let "n2=$year%100"
6 let "n3=$year%400"
7 if [ ! "$n1" -eq 0 ]
8 then
9 leap=0
10 elif [ ! "$n2" -eq 0 ]
11 then
12 leap=1
13 elif [ ! "$n3 -eq 0" ]
14 then
15 leap=0
16 else
17 leap=1
18 fi
19 if [ $leap -eq 1 ]
20 then
21 echo "$year is a leap year"
22 else
23 echo "$year is not a leap year"
24 fi
3、關于case的運用
case在條件後面必須跟一個in,然後下邊條件用alue)跟的條件語句結尾用兩個;;(分号),最後一個條件為*),最後用上esac。
1 #!/bin/sh
2 echo "Please input a month: "
3 read month
4 case $month in
5 1)
6 echo "yes 1 " ;;
7 2)
8 echo "no 2 " ;;
9 *)
10 echo "other " ;;
11 esac
4、關于for的應用
1)for的清單循環,循環體前用in 、,循環體用{ }大括号括起來,然後用do和done。
2)不帶清單的for循環,for後直接跟條件,然後用do和done。
3)類C風格的for循環,for後邊用(())兩層雙括号包覆條件,條件之間用;分号隔開,然後用do和done。
1 #!/bin/sh
2 sum=1
3 for (( i = 1 ;i <= 10 ;i++ ))
4 do
5 let sum*=i
6 echo sum =$sum
7 done
8 echo long sum ="$sum"
5、關于while的應用
1)在計數器中的while循環後邊必須用(())雙層小括号,然後用do和done。
2)其他條件下while後邊跟的條件必須用[[ ]]雙層中括号括起來或者[ ],然後用do和done。
1 #用腳本示範使用結束标記控制while循環實作猜1~10内的數
2 #!/bin/sh
3 echo "Please input the num (1~~10): "
4 read num
5 while [ $num != 4 ]
6 do
7 if [ $num -lt 4 ]
8 then
9 echo "Too small ,Try again.."
10 read num
11 elif [ $num -gt 4 ]
12 then
13 echo "Too big ,Try again.. "
14 read num
15 else
16 exit 0
17 fi
18 done
19 echo "Yes ,you are right !!"