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ShellScript(5) - if, and, or

 
  • Jul 25, 2020

if 문의 몇가지 예제를 통해 사용방법을 알아보도록 하겠습니다.


연산자 의미
x -eq y x가 y와 같은지 체크
x -ne y x가 y와 같지 않은지 체크
x -lt y x가 y 보다 작은지 체크
x -le y x가 y 보다 작거나 같은지 체크
x -gt y x가 y 보다 큰지 체크
x -ge y x가 y 보다 크거나 같은지 체크



예제.1 - simple if

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#!/bin/bash
n=10
if [ $n -lt 10 ];then
    echo "It is a one digit number"
else
    echo "It is a two digit number"
fi

$ ./simple_if.sh
It is a two digit number


예제.2 - AND연산 “&&”

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#!/bin/bash
echo "Enter username"
read username
echo "Enter password"
read password

if [[ ( $username == "admin" && $password == "secret" ) ]]; then
    echo "valid user"
else
    echo "invalid user"
fi

Enter username
admin
Enter password
secret
valid user
Enter username
admin
Enter password
12345
invalid user


예제.3 - OR연산 ||

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#!/bin/bash
echo "Enter any number"
read n

if [[ ( $n -eq 15 || $n  -eq 45 ) ]]
then
    echo "You won the game"
else
    echo "You lost the game"
fi

Enter any number
15
You won the game
Enter any number
45
You won the game
Enter any number
20
You lost the game


예제.4 - if ~ elif ~ else ~ fi

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#!/bin/bash
echo "Enter your lucky number"
read n
if [ $n -eq 101 ];then
    echo "You got 1st prize"
elif [ $n -eq 510 ];then
    echo "You got 2nd prize"
elif [ $n -eq 999 ];then
    echo "You got 3rd prize"
else
    echo "Sorry, try for the next time"
fi

Enter your lucky number
101
You got 1st prize
Enter your lucky number
510
You got 2nd prize
Enter your lucky number
999
You got 3rd prize
Enter your lucky number
9999
Sorry, try for the next time
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