IFS:

对IFS的用处直接进行说明，详细IFS是干什么的...自行谷歌

首先创建一个 "a a"，和"a"的文件:

然后我们 ls查看一下：

--> ls

a  a a

是这种。

然后假如我们须要写脚本操作每个文件：

--> for i in $(ls); do echo "$i" ;done

a

a

a

可是结果确实这种，显然与我们的要求不符

由于IFS的值是空格，制表符。回车。所以这里把a a变成了2个a

可是我们改动了IFS以后例如以下：

--> OldIfs=$IFS;IFS=$'\n';for i in $(ls); do echo "$i" ;done ;IFS=$OldIfs

a

a a

嗯，这样就达到了我们的目的，这个时候是以'\n'为切割符

数组：

一个脚本进行说明：

#!/bin/bash

# *-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*

#  > Author: xiaojunyu/LunaW

#  > Mail  : xiaojunyu5201314@163.com

#  > Gmail : lunaw.org@gmail.com

#  > Blog  : http://blog.csdn.net/lunaw

#  > Web   : http://lunaw.org http://lunaw.net

# *-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*

# DEPENDS:=+libsqlite3 +libcurl +libpthread +libc

# 默认选择的包

SelectPackages=(

"sed"

"gawk"

"grep"

"bc"

"luci-lib-json"

"iperf"

"tc"

"restorefactory"

"xinetd"

"n2n"

)

# 默认不选择的包 优先级强于选择的包

UnSelectPackages=(

"horst"

"vim-full"

"vim-runtime"

"qos-scripts"

"wifidog"

"libcurl"

"curl"

"tc"

"sqlite3-cli"

"libsqlite3"

)

if [[ -f .config ]]; then

    for Name in `seq 1 ${#SelectPackages[*]}`

    do

        PackageName="CONFIG_PACKAGE_${SelectPackages[$(expr $Name - 1)]}"

        if [[ `cat .config| grep "${PackageName}=y"| wc -l` == 0 ]]; then

            echo -e "\e[01;31mNot Found (${PackageName}=y) "

            if [[ `cat .config| grep "# ${PackageName} is not set"| wc -l` == 1 ]]; then

                echo -e "\e[01;33mFound (# ${PackageName} is not set) "

                sed -i "s/# ${PackageName} is not set/${PackageName}=y/g" .config

                echo -e "\e[01;36mReplace (${PackageName}=y) done!"

            else

                echo -e "\e[01;31mNot Found (# ${PackageName} is not set) "

                echo "${PackageName}=y" >> .config

                echo -e "\e[01;36mAdd (${PackageName}=y) done!"

            fi

        else

            echo -e "\e[01;33mFound (${PackageName}=y) "

        fi

    done

    echo "--------------------------------------"

    for Name in `seq 1 ${#UnSelectPackages[*]}`

    do

        PackageName="CONFIG_PACKAGE_${UnSelectPackages[$(expr $Name - 1)]}"

        if [[ `cat .config| grep "# ${PackageName} is not set"| wc -l` == 0 ]]; then

            echo -e "\e[01;31mNot Found (# ${PackageName} is not set) "

            if [[ `cat .config| grep "${PackageName}=y"| wc -l` == 1 ]]; then

                echo -e "\e[01;33mFound (${PackageName}=y) "

                sed -i "s/${PackageName}=y/# ${PackageName} is not set/g" .config

                echo -e "\e[01;36mReplace (# ${PackageName} is not set) done!"

            else

                echo -e "\e[01;31mNot Found (${PackageName}=y) "

                echo "# ${PackageName} is not set" >> .config

                echo -e "\e[01;36mAdd (# ${PackageName} is not set) done!"

            fi

        else

            echo -e "\e[01;33mFound (# ${PackageName} is not set) "

        fi

    done

else

    echo -e "\e[01;31mNot Found .config"

fi

echo -e "\e[01;00m+---------------------------------+"

echo -e "\e[01;00m|  不用操心，这仅仅是选择了几个包!  |"

echo -e "\e[01;00m+---------------------------------+"

sleep 1

替换：

单一替换

--> XiaoName="xiaojunyu"; echo "${XiaoName/x/j}"

jiaojunyu

所有替换

--> XiaoName="xiaojunyu"; echo "${XiaoName//u/a}"

xiaojanya

删除

--> XiaoName="xiaojunyu"; echo "${XiaoName//u/}"

xiaojny

分割：

有几种方法。第一种：

XiaoCh="xiao;jun;yu"

for i in ${XiaoCh//;/ }

do

    echo "$i"

done 

输出：

xiao

jun

yu

可是假如是这种话：

XiaoCh="xiao;j un;yu"

for i in ${XiaoCh//;/ }

do

    echo "$i"

done 

输出：

xiao

j

un

yu

并非我们预料的那样。然后另外一种切割方法

IFS法：

XiaoCh="xiao;j un;yu"

OldIFS=$IFS

IFS=$';'

XiaoArr=($XiaoCh)                                                                                                                        

for i in ${XiaoArr[@]}

do

    echo "$i"

done                                                                                                                                     

IFS=$OldIFS

输出：

xiao

j un

yu

查找：

查找一个字符串是否包括还有一个字符串

--> XiaoA="abc"; XiaoB="a"; [[ "${XiaoA/${XiaoB}/}" == "$XiaoA" ]] && echo "No" || echo "Yes"

Yes

--> XiaoA="abc"; XiaoB="w"; [[ "${XiaoA/${XiaoB}/}" == "$XiaoA" ]] && echo "No" || echo "Yes"

No