---------Linux Script Programming---for and while applications

Program programming

Select Execute

Sequential execution: If, case

Loop execution: For, while, until

For loop list

For i in LIST; Do loop body donefor i in Listdo loop body done

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While loop

While CONDITION; Do loop body Donewhile Conditiondo loop body donecondition cycle control condition, each time the loop body is executed, it needs to be judged true again, the loop is exited when the loop is false.

Exercise: Sum of all positive integers within 100

Exercise: within 100 all even and

Exercise: Add 10 users

Exercise: Use the ping command to detect the online status of all hosts within the 172.16.250.1-254 range. Using while loop

Exercise: printing 9x9 multiplication tables

Exercise: Use random to generate 10 random numbers, output these 10 numbers, and show the largest and smallest of the two

Exercise: Sum of all positive integers within 100

#!/bin/bash#declare-i sum=0for i in {1..100}; Dolet sum= $sum +1doneecho $iecho "Summary: $sum"

#!/bin/bash#declare-i sum=0declare-i i=1while [$i-le 100]; dosum=$[$sum + $i]let i++doneecho $iecho "Summary: $sum"

Exercise: within 100 all even and

#!/bin/bash#declare-i sum=0declare-i i=2while [$i-le 100]; dosum=$[$sum + $i]let i+=2doneecho $iecho "Summary: $sum"

Exercise: Add 10 users User1-user10

#!/bin/bash#declare-i i=1declare-i users=0while [$i-le 10]; Doid user$i &>/dev/nullretval=$? [$retval-ne 0] && useradd user$i &>/dev/null[$?-eq 0] && echo "ADD user user$i finished" &am p;& let users= $users +1doneecho "Add $users users"

Exercise: Use the ping command to detect the online status of all hosts within the 172.16.250.1-254 range. Using while loop

#!/bin/bash#declare-i ip= ' 172.16.250. ' Declare-i i=1declare-i uphosts=0declare-i downhosts=0while [$i-le 254]; Doif ping-c 1-w 1 $IP $i &>/dev/null; Thenecho "$IP $i is up" let Uphosts++elseecho "$IP $i are down" let Downhosts++fidoneecho "uphosts: $uphosts" echo "Downhosts: $ Downhosts "

Exercise: printing 9x9 multiplication tables

#!/bin/bash#for i in {1..9}; Dofor j in $ (SEQ 1 1 $i); Doecho-ne "${j}x${i}=$[$i * $j]\t" j=$ (($j + 1)) Doneechodone

#!/bin/bash#declare-i I=1while [$i-le 9]; Dodeclare-i j=1while [$j-le $i]; Doecho-ne "${j}x${i}=$[$i * $j]\t" j=$ (($j + 1)) doneechoi=$ (expr $i + 1) Done

Exercise: Use random to generate 10 random numbers, output these 10 numbers, and show the largest and smallest of the two

#!/bin/bash#declare -i max=declare -i min=declare -i i=1declare -i  randomwhile [  $i  -le 10 ]; dorandom= $RANDOMecho   $RANDOMIF  [  $i  -eq 1 ]; thenmax= $randommin = $maxfiif  [  $i  -gt 1 ]; thenif  [  $random  -gt  $max  ]; thenmax= $randomfiif  [  $random  -lt $ min ]; thenmin= $randomfifilet  i++doneecho  "max:  $max" echo  "min:  $min" ====== ====================================#!/bin/bash#declare -i max=declare -i min=declare  -i i=1declare -i randomwhile [  $i  -le 10 ]; dorandom=$ randomecho  $randomif  [  $i  -eq 1 ]; thenmax= $randommin = $maxfiif  [  $random  -gt  $max  ]; thenmax= $randomfiif  [  $random  -lt  $min  ];  thenmin= $randomfilet  i++doneecho  "max:  $max" echo  "min:  $min" 

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---------Linux Script Programming---for and while applications