쉘스크립트 기본 while문 until문

while문 - 주어진 조건이 참일경우 반복

형식

while [조건문]

do 

실행명령

done

---------------------

#!/bin/bash

cnt=1

while [ $cnt -lt 10 ]

do

echo "count"

cnt=`expr $cnt + 1`

done

---------------------

# ./while1.sh 

count

count

count

count

count

count

count

count

count

cnt 변수에 1을 대입하고 10보다 작을때까지 반복한다 숫자계산할때 expr명령어을 쓴다

----------------------------

#!/bin/bash

echo "your name is: "

read name

while [ "$name" != "tom" ];

do

echo "not name! your name is: "

read name

done

----------------------------

# ./while.sh 

your name is: 

tam

not name! your name is: 

jerry

not name! your name is: 

ton

not name! your name is: 

tom

-------------------

#!/bin/bash

while [ 1 ]

do

echo "do you like me?"

read ans

if [ "$ans" = "y" ]

then

break

else

continue

fi

done

echo "ok"

--------------------

# ./while2.sh 

do you like me?

y

ok

until문 - 조건이 참이될때 까지만 반복

형식

until [조건문]

do 

실행명령

done

-------------------------

#!/bin/bash

count=10

until [ "$count" -eq 0 ];

do

echo "count $count"

count=$(($count-1))

done

-------------------------

# ./until.sh 

count 10

count 9

count 8

count 7

count 6

count 5

count 4

count 3

count 2

count 1