shell编程举例（简单的）

[root@localhost Linuxos]# grep -rsn "codfei" /home/
/home/codfei/c/Unix_c/2:1:codfei::::::::::::::::::::::
/home/codfei/c/Unix_c/1:1:codfei::::::::::::::::::::::
Binary file /home/codfei/c/.charset.c.swp matches

[root@localhost Unix_c]# find /home/codfei/ -type f | while read i;do grep -n codfei $i && echo $i && echo -----;done
1:codfei::::::::::::::::::::::
/home/codfei/c/Unix_c/2
-----
1:codfei::::::::::::::::::::::
/home/codfei/c/Unix_c/1
-----
Binary file /home/codfei/c/.charset.c.swp matches
/home/codfei/c/.charset.c.swp
-----

#!/bin/bash

#最简单，效率最高的办法

mkdir -p /userdata/{1..50} && chmod 754 /userdata/{1..50}

#!/bin/bash

#利用seq命令加while read结构

seq 1 50 | while read i;do
   mkdir -p /userdata/$i
   chmod 754 /userdata/$i
done

#!/bin/bash

i=0
while [ $i -lt 50 ];do
   let i=i+1
   mkdir -p /userdata/$i
   chmod 754 /userdata/$i
done

#!/bin/bash

for ((i=1;i<=50;i++));do
   mkdir -p /userdata/$i
   chmod 754 /userdata/$i
done

#!/bin/sh


for D in user{1..50}
do
mkdir -m 754 -p $D
done

echo -e "`date`\n`cat ABC.txt`" > ABC.txt
echo "`date | cat - ABC.txt`" > ABC.txt
sed -i "1i`date`" ABC.txt