14, Practical cases of enterprises
(1) Use the for loop to batch create 10 html files in the / oldboy directory, where the file name contains 10 random lowercase letters plus a fixed string 0ldoby.
Train of thought analysis and random number generation method:
① The core is to create 10 random lowercase letters.
echo $RANDOM range is 0-32767
openssl rand -base64 100
date +%s%N
head /dev/urandom/cksum
uuidgen
cat /proc/sys/kernel/random/uuid
mkpasswd (yum install expect -y)
-l: Length
-d: Figures
-c: Lowercase letters
-C: Capital letter
-s: Special characters
[root@centos6-kvm3 shili]# cat 14-01.sh
#!/bin/bash
path="oldboy"
[ -d /path ] || mkdir -p oldboy/
for n in {1..10}
do
random=`echo "OLDBOY$RANDOM" | md5sum | tr '0-9' 'm-z' | cut -c 2-11`
touch $path/${random}_oldboy.html
done
[root@centos6-kvm3 shili]#
(2) . special cases of batch renaming. Change the oldboy string in the result file name in the above interview question 1 to oldgirl (preferably implemented with a for loop), and change the extension html to uppercase.
[root@centos6-kvm3 shili]# cat 14-02.sh
#!/bin/bash
for file in `ls oldboy/*.html`
do
mv $file ${file/oldboy.html/oldgirl.HTML}
done
[root@centos6-kvm3 shili]#
Method 2
[root@centos6-kvm3 oldboy]# ls | awk -F "oldgirl.HTML" '{print "mv",$0, $1 "oldboy.html"}' | bash
Method 3
[root@centos6-kvm3 oldboy]# rename "oldboy.html" "oldgirl.HTML" *.html
(3) Enterprise shell interview question 3: create user cases with special requirements in batch.
Create 10 system accounts oldboy01-oldboy10 in batch and set the password (the password is a random number and requires a mixture of numbers and letters).
Method 1
[root@centos6-kvm3 shili]# cat 14-03.sh
#!/bin/bash
. /etc/init.d/functions
if [ $UID -ne 0 ]
then
echo "please use root."
exit 1
fi
for n in {41..50}
do
pass=`openssl rand -base64 10`
if [ `grep -w "oldboy$n" /etc/passwd|wc -l` -eq 0 ]
then
useradd oldboy$n &>/dev/null &&\
echo $pass | passwd --stdin oldboy$n &&\
echo -e "oldboy$n\t$pass" >>/tmp/user.txt &&\
action "oldboy$n is successful." /bin/true
else
action "oldboy$n is exist." /bin/false
fi
done
[root@centos6-kvm3 shili]#
Method 2
[root@centos6-kvm3 shili]# cat 14-03-01.sh #!/bin/bash for n in `seq -w 11 20` do pass=`openssl rand -base64 10` useradd oldboy$n echo "oldboy$n:$pass" >>/tmp/chpasswd.log done chpasswd </tmp/chpasswd.log [root@centos6-kvm3 shili]#
(4) Scan network memory for live host cases. Write a shell script to judge the number of hosts in the current network at 10.0.0.0/24. What are currently online.
How to judge whether the host is alive.
①ping
-c times
-i interval
②nmap (yum)
nmap -sP 10.0.0.0/24
Method 1
[root@centos6-kvm3 shili]# cat 14-04.sh
#!/bin/bash
for n in {1..254}
do
{
if `ping -c 1 -w 3 10.0.0.$n &>/dev/null`
then
echo "10.0.0.$n is up."
else
echo "10.0.0.$n is down."
fi
} &
done
Method 2
[root@centos6-kvm3 shili]# nmap -sP 10.0.0.0/24 | awk '/Nmap scan report for/{print $NF}'
(5) . mysql database sub database backup
mysql -uroot -poldboy123 -e "show databases" | grep -v _scheme|sed -1d
Sub database backup:
mysqldump -B oldboy | gzip > bak.sql.gz
[root@centos6-kvm3 scripts]# vim mysql.sh
#!/bin/bash
path=/back
[ -d $path ] || mkdir $path -p
for dbname in `mysql -uroot -poldboy123 -e "show databases;" 2>/dev/null | grep -v _schema | sed -1d`
do
mysqldump -uroot -poldboy123 -B $dbname | gzip >$path/${dbname}.sql.gz
done
(6) Case analysis and development of mysql database and table backup
How to realize the backup of sub database and sub table in mysql database, please use script.
answer:
mysqldump oldboy test test1| gzip >bak.sql.gz
1. Oldboy library name
2. test\test1 are all table names
method:
mysqldump -B oldboy |gzip >bak.sql.gz
mysqldump oldboy test1
mysqldump -B oldgril | gzip >bak.sql.gz
mysqldump oldgril test1
mysql -uroot -poldboy123 -e "show tables from wordpress;" 2>/dev/null | sed -1d
[root@centos6-kvm3 scripts]# cat mysql.sh
#!/bin/bash
path=/back
[ -d $path ] || mkdir $path -p
for dbname in `mysql -uroot -poldboy123 -e "show databases;" 2>/dev/null | grep -v _schema | sed 1d`
do
for tname in `mysql -uroot -poldboy123 -e "show tables from $dbname;" 2>/dev/null | grep 1d `
do
if [ "$dbname" = "mysql" ]
then
mysqldump -uroot -poldboy123 $dbname $tname | gzip >$path/${dbname}_${tname}.sql.gz
else
mysqldump $dbname $tname | gzip >$path/${dbname}_${tname}.sql.gz
fi
done
done
[root@centos6-kvm3 scripts]#
7, SSH secret key free batch distribution file professional script
There are three machines, m01, backup and nfs01. ssh free secret key is used to log in from m01 to the other two machines without password. After logging in, please write a script to batch distribute any files from m01 to any directory of the other two machines.
Secret free environment generation:
[root@centos6-kvm3 scripts]# ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Created directory '/root/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
12:af:26:77:1e:2d:2b:ce:94:aa:f9:be:c5:a3:c8:90 root@centos6-kvm3
The key's randomart image is:
+--[ RSA 2048]----+
| |
| |
| . |
| o |
| . S |
| . . + . |
|E . X + . |
| o o X.+ + |
| =+*oo.o |
+-----------------+
[root@centos6-kvm3 scripts]# ll ~/.ssh/
total 8
-rw------- 1 root root 1675 Jan 27 21:48 id_rsa
-rw-r--r-- 1 root root 399 Jan 27 21:48 id_rsa.pub
[root@centos6-kvm3 scripts]# cd ~/.ssh/
[root@centos6-kvm3 .ssh]# ssh-copy-id id_rsa.pub 10.0.0.8
[root@centos6-kvm3 scripts]# cat fenfa.sh
#!/bin/bash
. /etc/init.d/functions
if [ $# -ne 2 ]
then
echo "usage:$0 localdir remotedir"
exit 1
fi
for n in 8 41 43
do
scp -rp $1 10.0.0.$n:$2 &>/dev/null
if [ $? -eq 0 ]
then
action "10.0.0.$n is successful" /bin/true
else
action "10.0.0.$n is failure" /bin/false
fi
done
[root@centos6-kvm3 scripts]#
8, Cracking RANDOM number cases
It is known that the following string is the result of intercepting part of the string after passing through the RANDOM number variable md5sum. Please crack the number corresponding to the RANDOM number before md5sum processing.
21029299
00205d1c
a3da1677
1f6d12dd
890684b
answer:
[root@centos6-kvm3 .ssh]# cat random.sh
#!/bin/bash
array=(
21029299
00205d1c
a3da1677
1f6d12dd
890684b
)
funmd5(){
for n in {1..32767}
do
echo "$n\t `$n|md5sum`" >>/tmp/md5sum.log
done
}
funjudge(){
for n in ${array[*]}
do
if [ `echo grep $n /tmp/md5sum.log|wc -l` -eq 1 ]
then
echo `grep $n /tmp/md5sum.log`
fi
done
}
main(){
funmd5
funjudge
}
main
[root@centos6-kvm3 .ssh]#
Optimization method 1:
[root@centos6-kvm3 .ssh]# cat random1.sh
#!/bin/bash
array=(
21029299
00205d1c
a3da1677
1f6d12dd
890684b
)
funmd5(){
for n in {1..32767}
do
echo "$n\t `$n|md5sum`" >>/tmp/md5sum1.log
done
}
funjudge(){
char="`echo ${array[*]} | tr " " "|"`"
egrep $char /tmp/md5sum1.log
}
main(){
funmd5
funjudge
}
main
[root@centos6-kvm3 .ssh]#
9, Batch check whether multiple website addresses are normal
Enterprise interview question: batch check whether multiple website addresses are normal.
requirement:
1. The shell array method is used to implement the inspection strategy, and the user access is simulated as much as possible.
2. All tests shall be carried out every 10s, and the inaccessible output alarm.
3. The addresses to be tested are as follows:
answer:
wget --spider # simulates a crawler without downloading html files.
Method 1
[root@centos6-kvm3 .ssh]# cat url.sh
#!/bin/bash
. /etc/init.d/functions
array=(
http://blog.oldboyedu.com
http://www.baidu.com
http://blog.ettiantian.org
http://www.luffycity.com
http://10.0.0.7
)
checkurl(){
wget -t 2 -T 5 -o /dev/null -q $1
if [ $? -eq 0 ]
then
action "$1 is successfull." /bin/true
else
action "$1 is failure." /bin/false
fi
}
dealurl(){
for n in ${array[*]}
do
checkurl $n
done
}
main(){
while true
do
dealurl
sleep 2
echo "--------"
done
}
main
[root@centos6-kvm3 .ssh]#
Method 2
[root@centos6-kvm3 .ssh]# cat url1.sh
#!/bin/bash
. /etc/init.d/functions
array=(
http://blog.oldboyedu.com
http://www.baidu.com
http://blog.ettiantian.org
http://www.luffycity.com
http://10.0.0.7
)
checkurl(){
wget -t 2 -T 5 -o /dev/null -q $1
if [ $? -eq 0 ]
then
action "$1 is successfull." /bin/true
else
action "$1 is failure." /bin/false
fi
}
dealurl(){
for ((i=0;i<${#array[*]};i++))
do
checkurl ${array[$i]}
done
}
main(){
while true
do
dealurl
sleep 2
echo "--------"
done
}
main
[root@centos6-kvm3 .ssh]#
Method 3
[root@centos6-kvm3 .ssh]# cat url2.sh
#!/bin/bash
. /etc/init.d/functions
checkurl(){
wget -t 2 -T 5 -o /dev/null -q $1
if [ $? -eq 0 ]
then
action "$1 is successfull." /bin/true
else
action "$1 is failure." /bin/false
fi
}
dealurl(){
while read line
do
checkurl $line
done < ./url.log
}
main(){
while true
do
dealurl
sleep 2
echo "--------"
done
}
main
[root@centos6-kvm3 .ssh]#
10, Solve dos attack generation cases
Write a shell script to solve the dos attack and generate cases.
Please monitor the number of concurrent connections of an ip according to the web log or the number of network connections, or pv reaches 100 in a short time (please set it according to the actual situation), that is, call the firewall command to block the corresponding ip. Firewall command: iptables -I INPUT -s IP address - j DROP
answer:
DOS deny of service
DDOS
analysis:
1. ip sealing command
iptables -I INPUT -s IP address - j DROP
2. Number of web logs or network connections
Log files, netstat -an| grep -i est sort and de duplicate.
3. Judge whether pv or the number of connections is greater than 100, take out the ip and seal it.
Method of taking attack ip:
Method 1
[root@centos6-kvm3 scripts]# awk '{s[$1]++}END{for(key in s) print s[key],key}' access_2010-12-8.log | uniq |sort -nr
35 59.33.26.105
23 123.122.65.226
8 124.115.4.18
Method 2
[root@centos6-kvm3 scripts]# awk '{print $1}' access_2010-12-8.log | uniq -c | sort -nr
35 59.33.26.105
23 123.122.65.226
8 124.115.4.18
[root@centos6-kvm3 scripts]#
[root@centos6-kvm3 scripts]# cat dos.sh
#!/bin/bash
awk '{s[$1]++}END{for(key in s) print s[key],key}' access_2010-12-8.log |sort -nr | head >/tmp/ip.log
while read line
do
ip=`echo $line|awk '{print $2}'`
count=`echo $line|awk '{print $1}'`
if [ $count -gt 30 -a `grep "$ip" /tmp/drop.log|wc -l` -lt 1 ]
then
iptables -I INPUT -s `echo $line|awk '{print $2}'` -j DROP &&\
echo "echo $line|awk '{print $2}'" >>/tmp/drop.log
else
echo "echo $line|awk '{print $2}'" >>/tmp/accept.log
fi
done </tmp/ip.log
[root@centos6-kvm3 scripts]#
[root@centos6-kvm3 scripts]# iptables -nL
How to get the number of network connections:
[root@centos6-kvm3 scripts]# awk -F "[ :]+" '/ESTAB/{S[$(NF-3)]++}END{for(k in S) print S[k],k}' netstat.log| sort -rn | head
[root@centos6-kvm3 scripts]# awk '/ESTAB/{print $(NF-1)}' netstat.log | awk -F ":" '{print $1}'| uniq -c | sort -rn |head
[root@centos6-kvm3 scripts]# vim dos1.sh
#!/bin/bash
awk -F "[ :]+" '/ESTAB/{S[$(NF-3)]++}END{for(k in S) print S[k],k}' netstat.log| sort -rn | head >/tmp/ip.log
while read line
do
ip=`echo $line|awk '{print $2}'`
count=`echo $line|awk '{print $1}'`
if [ $count -gt 30 -a `grep "$ip" /tmp/drop.log|wc -l` -lt 1 ]
then
iptables -I INPUT -s `echo $line|awk '{print $2}'` -j DROP &&\
echo "echo $line|awk '{print $2}'" >>/tmp/drop.log
else
echo "echo $line|awk '{print $2}'" >>/tmp/accept.log
fi
done </tmp/ip.log
~ [root@centos6-kvm3 scripts]# iptables -nL
11, Develop mysql service start stop script
Requirements: implemented with functions, case statements, if statements, etc.
answer:
/etc/init.d/mysqld {start | stop | restart}
analysis:
1. Start
mysql_ Safe -- user = MySQL & be sure to test successfully on the command line.
2. Stop
mysqladmin -uroot -ppasswd shutdown
killall,pkill
kill pid recommendation
[root@centos6-kvm3 scripts]# cat mysqld.sh
# chkconfig: 2345 20 80
# description: mysql start stop
#!/bin/bash
lockfile=/var/lock/subsys/mysqld
. /etc/init.d/functions
mysqld_pid_file_path="/application/mysql/data/web01.pid"
mysqld_safe=/application/mysql/bin/mysqld_safe
start(){
/bin/sh $mysqld_safe --datadir=/application/mysql/data --pid-file=$mysqld_pid_file_path &>/dev/null &
retval=$?
if [ $retval -eq 0 ]
then
action "mysql start ok" /bin/true
touch $lockfile
return $retval
else
action "mysql start fail" /bin/false
return $retval
fi
}
stop(){
if test -s "$mysqld_pid_file_path"
then
mysqld_pid=`cat $mysqld_pid_file_path`
if (kill -0 $mysql_pid &>/dev/null)
then
kill $mysqld_pid
retval=$?
if [ $retval -eq 0 ]
then
action "mysql stop ok" /bin/true
rm $lockfile
return $retval
else
action "mysql stop fail" /bin/false
return $retval
fi
else
echo "mysqld process is not exits."
return 2
fi
else
echo "$mysqld_pid_file_path is not exist,or mysqld does not startup."
fi
}
case $1 in
start)
start
retval=$?
;;
stop)
stop
retval=$?
;;
restart)
stop
sleep 2
start
retval=$?
;;
*)
echo "usage:$0 {start|stop|restart}"
exit 1
esac
exit $retval
[root@centos6-kvm3 scripts]#
12, Word and letter de reordering case
Process the following with a shell script
1. Sort words in descending order of frequency.
2. Sort alphabetically in descending order.
the squid project provides a number of resources to assist users design,implement and support squid installations. Please browse the documentation and support sections for more infomation,by oldboy training.
1. Sort words in descending order of frequency.
Method 1:
[root@centos6-kvm3 scripts]# tr " ," "\n" <12.log | sort|uniq -c| sort -rn
Method 2:
[root@centos6-kvm3 scripts]# tr " ," "\n" <12.log | awk '{S[$1]++}END{for(k in S) print S[k],k}'| sort -nr
Method 3
[root@centos6-kvm3 scripts]# xargs -n1 <12.log | sort|uniq -c|sort -nr
2. Sort Letters in descending order of frequency.
Method 1
[root@centos6-kvm3 scripts]# grep -o "[^ ]" 12.log | sort|uniq -c|sort -nr
Method 2
[root@centos6-kvm3 scripts]# grep -o "[^ ]" 12.log | awk '{S[$1]++}END{for(k in S) print S[k],k}'|sort -rn
Method 3
[root@centos6-kvm3 scripts]# sed 's#[ ,\.]##g' 12.log | awk -F "" '{for(i=1;i<NF;i++)s[$i]++}END{for(k in s) print s[k],k}'| sort -nr
13, Advanced method of sorting cases by word
Vertical treatment:
[root@centos6-kvm3 scripts]# awk -F '[ ,.]+' '{for(i=1;i<NF;i++)s[$i]++}END{for(k in s) print s[k],k}' 12.log | sort -nr