shell面试题汇集,shell试题汇集一般用if [ !

shell面试题汇集,shell试题汇集一般用if [ !

利用top取某个进程的CPU的脚本:

#/bin/sh

Max_CPU=0

Avg_CPU=0

Total_Time=1

Process=$1

Interval=$2

# check the parameters

if [ $# -ne 2 ]; then

echo "Usage: $0 ProcessName Interval"

exit

fi

LogFile="Per.txt"

echo "`date`" > $LogFile

while sleep $Interval

do

top -d 1 -n 1|grep $Process|grep -v grep|awk '{print $9"t"$10}' >> $LogFile

done

判断是否是设备文件

#/bin/bash

echo -e "The program will Judge a file is or not a device file.nn"

read -p "Input a filename:" filename

if [ -b $filename -o -c $filename ]; then

echo "$filename is a device file"

exit 0

else

echo "$filename is not a device file"

exit 1

firead –p：用于在读数据时输出提示信息

注意！[之间是有空格的：if ! [ -f $filename ] ; then。一般用if [ ! * ]

添加用户：

#/bin/bash

groupadd -f class1

for i in {9909..9911}

do

xx=`echo $i | sed 's/99//g'`

useradd -g class1 std${xx}

echo std${xx} | passwd std${xx} --stdin

echo -e "user std${xx} passwd is std${xx}">>/root/newuser.txt

done

exit 0

注意等号的前后不要有空格：xx=`echo $i | sed 's/99//g'`

变量如果前后有字符，要是大括号

统计IP访问：

要求分析apache访问日志，找出访问页面数量在前100位的IP数。日志大小在78M左右。以下是apache的访问日志节选

202.101.129.218 - - [26/Mar/2006:23:59:55 +0800] "GET /online/stat_inst.php?pid=d065 HTTP/1.1" 302 20-"-" "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)"

# awk '{print $1}' log|sort |uniq -c|sort -r |head -n10

5 221.224.78.15

3 221.233.19.137

1 58.63.148.135

1 222.90.66.142

1 222.218.90.239

1 222.182.95.155

1 221.7.249.206

1 221.237.232.191

1 221.235.61.109

1 219.129.183.122

这个地方有个疑问，为什么在使用uniq之前要sort。

求2个数之和

#/bin/bash

typeset first second

read -p "Input the first number:" first

read -p "Input the second number:" second

result=$[$first+$second]

echo "result is : $result"

exit 0

文本分析

取出password中shell出现的次数

第一种方法结果:

4 /bin/bash

1 /bin/sync

1 /sbin/halt

31 /sbin/nologin

1 /sbin/shutdown

第二种方法结果:

/bin/sync 1

/bin/bash 1

/sbin/nologin 30

/sbin/halt 1

/sbin/shutdown 1

答案：

cat /etc/passwd|awk -F: '{if ($7!="") print $7}'|sort|uniq –c

cat /etc/passwd|awk -F: '{if ($7!="") print $7}'|sort|uniq -c | awk '{print $2,$1}'

文件整理

employee文件中记录了工号和姓名

employee.txt:

100 Jason Smith

200 John Doe

300 Sanjay Gupta

400 Ashok Sharma

bonus文件中记录工号和工资

bonus.txt:

100 $5,000

200 $500

300 $3,000

400 $1,250

要求把两个文件合并并输出如下

处理结果:

400 ashok sharma $1,250

100 jason smith $5,000

200 john doe $500

300 sanjay gupta $3,000

答案：join employee bonus | sort -k 2

打印本机的交换分区大小

处理结果:

Swap:1024M

free -m | sed -n '/Swap/p' | awk '{ print $2}'

free -m | sed -n 's/Swap: *([0-9]*).*/1/p'

输出本机创建20000个目录所用的时间

处理结果:

real0m3.367s

user0m0.066s

sys0m1.925s

答案：

# time for i in {1..2000} ; do mkdir /root/neil$i; done

real0m6.200s

user0m1.128s

sys0m4.710s

打印当前sshd的端口和进程id

处理结果:

sshdPort&&pid: 22 5412

答案：netstat -anp | grep sshd | sed -n 's/.*:::([0-9]*) .* ([0-9]*)/sshd/1 2/p'

打印root可以使用可执行文件数

处理结果:

root's bins: 2306

echo "root's bins: $(find ./ -type f | xargs ls -l | sed '/-..x/p' | wc -l)"

root's bins: 3664

编译当前目录下的所有.c文件：

for file in *.c; do echo $file ; gcc -o $(basename $file .c) $file; sleep 2;done > compile 2>&1

将一目录下所有的文件的扩展名改为bak

for i in *.*;do mv $i ${i%%.*}.bak;done