shell简单使用(－)判断

记几个判断相关的简单例子

１. 文件相关判断比较

#!/bin/bash
if [ $# -lt 1 ]
    then
    echo "No file name"
    exit 1
elif [ -d $1 ]
    then
    echo $1 is directory
elif [ -b $1 ]
    then 
        echo $1 is block device
elif [ -h $1 ]
    then
        echo $1 is link file
elif [ -c $1 ]
    then
        echo $1 is character device
elif [ -f $1 ]
    then
        echo $1 is normal file
else 
    echo "Don't recognize $1"
fi

if [ -r $1 ]
    then
        echo $1 is can be read
fi

if [ -w $1 ]
    then 
        echo $1 is can be write
fi

if [ -x $1 ]
    then
        echo $1 is can be excute
fi

if [ -u $1 ]
    then
        echo $1 has SUID attribution
fi

if [ -g $1 ]
    then
        echo $1 has SGID attribution
fi

if [ -k $1 ]
    then
        echo $1 has Sticky bit attribution
fi

if [ -s $1 ]
    then
        echo $1 is a xxx
fi


exit 0

执行结果如下：

2. 数字相关判断

a.

#!/bin/bash

if [ "$1" -eq "$2" ]; then
# if [ "$1" -ne "$2" ]; then
    echo $1 equal $2

fi

if [ "$1" -lt "$2" ]; then
# if [ "$1" -le "$2" ]; then
    echo $1 less than $2
fi

if [ "$1" -gt "$2" ]; then
# if [ "$1" -ge "$2" ]; then
    echo $1 grate then $2
fi

b.

#!/bin/bash

read -p "Input the age: " age

case $age in

    [0-9]|[1][0-2])
        echo "child"
        ;;
    [1][0-9])
        echo "young"
        ;;
    [2-5][0-9] )
        echo "adult"
        ;;
    [6-9][0-9])    
        echo "old"
        ;;
    *    )
        echo "Not people"
        ;;
esac
exit 0

执行结果如下：

b. 

#!/bin/bash

read -p "Iuput your birthday (MMDD.ex> 0709): " bir
now=`date +%m%d`

if [ "$bir" == "$now" ];then
　　echo "Happy birthday !!!"
elif [ "$bir" -gt "$now" ];then
　　year=`date +%Y`
　　total_d=$(($((`date --date="$year$bir" +%s`-`date +%s`))/60/60/24))
　　echo "Your birthday will be $total_d later"
else
　　year=$((`date +%Y`+1))
　　total_d=$(($((`date --date="$year$bir" +%s`-`date +%s`))/60/60/24))
　　echo "Your birthday will be $total_d later"
fi

执行结果如下：

３. 字符串比较

#!/bin/bash

if [ "$1" == "$2" ]; then
# if [[ "$1" == "$2" ]]; then
    echo $1 equal $2
fi

if [ "$1" != "$2" ]; then
    echo $1 no equal $2
fi

if [[ "$1" > "$2" ]]; then
# if [ "$1" \> "$2" ]; then
    echo $1 grate then $2
fi

if [[ "$1" < "$2" ]]; then
# if [ "$1" \< "$2" ]; then
    echo $1 less then $2
fi

if [ -z "$1" ]; then
    echo $1 is empty
fi

if [ -n "$1" ]; then
    echo $1 is no empty
fi

if [[ "$1" == 1* ]]; then
    echo $1 ==  "1*" 1111111111
fi

if [[ "$1" == "1*" ]]; then
    echo $1 == \"1*\" 2222222222
fi

执行结果如下：

两次对1*的比较，分别是模式匹配和全字符串匹配