Until loop statements

Script Programming Control Structure

Order

Select

If

Case

Loops

For

While

Until

While format:

While Condition;do

Statment

Done

Enter loop: Condition satisfies

Exit Loop: Condition not satisfied

Until format:

Until Condition;do

Statment

Done

Enter loop: Condition not satisfied

Exit Loop: Condition satisfies

#!/bin/bash#read-p "Input Something:" stringuntil [$STRING = = ' quit ']; Do echo $STRING | Tr ' A-Z ' A-Z ' read-p "Input Something:" Stringdone

#!/bin/bash#until who |   grep "root" &>/dev/null;d o echo "root not login." Sleep 5done echo "root is login."

For structure:

1.

For variable in;d o

Loop body

Done

2.

For ((EXPR1;EXPR2;EXPR3));d o

Loop body

Done

#!/bin/bash#declare sum=0for I in {1..100};d o let sum+= $Idoneecho $SUMdeclare sum2=0for ((j=1; j<=100; J + +));d o let sum2+= $Jdoneecho $SUM 2

Calculates the arithmetic between 1 and 100 using the two formats for the for statement

#!/bin/bash#for2.shdeclare sum=0for ((i=2;i<=100;i+=2));d o let sum+= $Idoneecho $SUM

Calculates an even number within 100 and

awk ' pattern{action} ' file

Print $

$NF: Last Field

-F: Specifies that the delimiter is:

Fdisk-l 2>/dev/null | grep "^disk/dev/[sh]d[a-z" | Awk-f: ' {print '} '

Find all the hard drives on the server

Write a script (provided that you add a hard disk to the virtual machine, assuming it is/dev/sdb) and create a partition for the specified hard disk:

1, list all the disks on the current system, let the user choose, if you choose Quit to quit the script, if the user chooses the error, let the user choose again;

2, when the user selects, remind the user to confirm that the next operation may damage the data, and ask the user to confirm; if the user chooses Y to continue, n exits; otherwise, let the user re-select;

3. Erase all partitions on the hard drive (prompt, erase all partitions after the Sync command, and let the script sleep for 3 seconds before partitioning), and create three primary partitions for it, the first one is 20M, the second is 512M, the third is 128M, and the third is the swap partition type; Hint: The partition command is delivered to Fdisk via Echo)

#!/bin/bash#echo -e  "\033[31minitial a disk ...\033[0m" echo -e  "\033[ 31mwarning....\033[0m "echo " You have the following disk "fdisk -l |  grep  "^disk /dev/[sh]d[a-z"  | awk -F:  ' {print $1} '  | awk     ' {print $2} ' read -p  "Enter your choice:"  choiceif [ $ choice ==  ' quit '  ];then   echo  ' quting ... '    exit  0fiuntil fdisk -l | grep  "^disk /dev/[sh]d[a-z"  | grep  "^Disk   $CHOICE "  &> /dev/null;do    read -p " wrong  Option,enter your choice aging: " CHOICEdoneread -p " Will destory all  format data,continue? y/n: " CHOICE2until [  $CHOICE 2 ==  ' Y '  -o   $CHOICE 2 ==  ' N '  ];d o    read -p  "will destory all format data,continue? y/n : " CHOICE2doneif [  $CHOICE 2 ==  ' N '  ];then   echo " quiting .... "   exit 7elsedd if=/dev/zero of= $CHOICE  bs=512 count=1 & > /dev/nullsyncsleep 3echo  ' np1+20mnp2+150mnp3+128mt382w '  | fdisk  $CHOICE  &> /dev/nullsleep 1syncmke2fs -j ${choice}1 &> /dev/ Nullsleep 2mke2fs -j ${choice}2 &> /dev/nullsleep 2mkswap ${choice}3  &> /dev/nullfi

Until loop statements