shell--Simple Exercises

First, calculate the value of 1+2+...+100

Use the General method:

   #! /bin/bash      sum=0   res= ""     num=1   for  ((;  num<=100; num++))    do        let sum+=num         [ $ num -eq 100 ]&&{          res=${res}$ {num}          break      }         res=${res}${num} ' + '                                                           done  echo ${res}=${sum }

The results are as follows:

650) this.width=650; "src=" Http://s1.51cto.com/wyfs02/M00/83/12/wKiom1dqKrCya1xzAABmDYIlK7A842.png "title=" 1+...+ 100.png "alt=" Wkiom1dqkrcya1xzaabmdyilk7a842.png "/>

Use recursive methods:

  1 #! /bin/bash  2   3 read num  4    5 sum=0  6 function add ()   7 {  8      num1= $num   9     [  $num  -le 1 ]& &{ 10         echo  "$num"  11          return 12     } 13  14      let num-- 15     tmp=$ (add  $num)  16      let sum= $num 1+ $tmp                                                           17     echo  "$sum"  18 } 19   20 add  $num

The results are as follows:

650) this.width=650; "src=" Http://s3.51cto.com/wyfs02/M00/83/11/wKioL1dqK02xuCRZAAA3CiR00Aw232.png "title=" 1+...+ 100 recursive. png "alt=" Wkiol1dqk02xucrzaaa3cir00aw232.png "/>

Second, the fee spectrum Nahan number

(1) The array method is used: (saves each number calculated)

1 #!  /bin/bash 2 3 Read Val 4 arr[0]=1 5 arr[1]=1 6 i=0 7 while [$i-le $val] 8 does 9 let Arr[i+2]=arr[i+1]+arr[i] ten let i++ one-done and Echo ${arr[val]}

The results are as follows:

650) this.width=650; "src=" Http://s5.51cto.com/wyfs02/M02/83/11/wKioL1dqK-mA3pp0AABjZ0Jm63o249.png "title=" fib_ Array. png "alt=" Wkiol1dqk-ma3pp0aabjz0jm63o249.png "/>

(2) Using recursion method: (Low efficiency)

1 #! /bin/bash 2 3 Read num 4 5 function fib () 6 {7 [$num-le 1]&&{8 echo "$num" 9 re Turn--num val1=$ (fib $num)--num val2=$ (fib $num) let val= $val 1+$ Val2 echo "$val", fib num

The results are as follows:

650) this.width=650; "src=" Http://s4.51cto.com/wyfs02/M02/83/12/wKiom1dqLCiCAhKaAABzYuXY2QQ931.png "title=" fib_ Recursive. png "alt=" Wkiom1dqlcicahkaaabzyuxy2qq931.png "/>

Three, string splicing

Chestnut Code:

1 #!  /bin/bash 2 3 While read line 4 do 5 str1=$ (echo $line |cut-c 1-3) 6 str2=$ (echo $line |cut-c 4-6|tr ' [A-z] '                                                ' [A-z] ') 7 str3=$ (echo $line |cut-c 7-9) 8 echo ${str3}${str2}${str1} 9 Done<file

The results are as follows:

650) this.width=650; "src=" Http://s3.51cto.com/wyfs02/M01/83/11/wKioL1dqLHfBjytnAABos7Hqmt0812.png "title=" string concatenation. png "alt=" Wkiol1dqlhfbjytnaabos7hqmt0812.png "/>

Iv. simulating a simple progress bar

Chestnut Code:

1 #! /bin/bash 2 3 val=100 4 str= "" 5 arr= (' | ') '/'-' \ \ ') 6 for ((I=1; i<=val; i++)) 7 does 8 str+= "#" 9 let index=i%4 ten printf "[%-100s] [${i}%%] [$ {arr[$index]}] \ r "" ${str} "one sleep 0.5" \ n "

The results are as follows:

650) this.width=650; "src=" Http://s1.51cto.com/wyfs02/M00/83/12/wKioL1dqLMmzIYz8AABTc0iDwNo277.png "style=" float: none; "title=" Jindutiao1.png "alt=" Wkiol1dqlmmziyz8aabtc0idwno277.png "/>

650) this.width=650; "src=" Http://s4.51cto.com/wyfs02/M02/83/12/wKioL1dqLM_ifON8AABBS2lXiYI158.png "style=" float: none; "title=" Jindutiao2.png "alt=" Wkiol1dqlm_ifon8aabbs2lxiyi158.png "/>

V. Find the maximum minimum value of the number in the file

Chestnut Code:

  1 #! /bin/bash  2   3 count=0  4 while  read line  5 do  6     let count++                                                                   7     [  $count  -eq 1  ]&&{  8         min= $line   9          max= $line  10     } 11      [  $max  -lt  $line  ]&&{ 12           max= $line  13     } 14  15     [ $ min -gt  $line  ]&&{ 16         min=$ line 17     } 18 done<file 19 echo min= $min, max= $max

The results are as follows:

650) this.width=650; "src=" Http://s1.51cto.com/wyfs02/M02/83/12/wKioL1dqLSnzoGYVAABC52XgLoo621.png "title=" Min_ Max.png "alt=" Wkiol1dqlsnzogyvaabc52xgloo621.png "/>

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shell--Simple Exercises