shell编程-4

不冤不乐2024-01-19 11:44

正则表达式

正则表达式

一个重要的命令: grep---->过滤文本

1.什么是正则表达式

正则表达式: regular expression 本质上是:一种思想，方法。

理解为一套方法或者工艺

别的命令采用这套方法，去查找内容

按照某种正确的规则，将字母，数字，特殊符号组合成一个公式，用来表达某个意思

作用: 一些查找类的命令，喜欢使用正则表达式去搜索符合条件的内容

写正则表达式 就是根据某个特点，使用规则表示出来，然后grep可以根据这个规律去查找

2.明确一个知识点: shell的解析流程

  1. **在输入一条命令的时候 会将命令分割成 tokens 比方说 mkdir -p gao{1...20} **

  2. 先查看mkdir检查是不是关键字

  3. 检查第一个token是不是别名

  4. 然后看看有没有波浪符号

  5. 再看有没有变量替换

  6. 再看有没有命令替换(优先级高)

  7. 看有没有算数表达式

  8. 再看展开的文本进行单词的分割

  9. 展开通配符

  10. 命令查找

  11. 执行命令

  12. eval会再执行一下

    **eval命令将会首先扫描命令行进行所有的替换，然后再执行命令。该命令使用于那些一次扫描无法实现其功能的变量。该命令对变量进行两次扫描。这些需要进行两次扫描的变量有时候被称为复杂变量 **

    shell 复制代码 
    两次扫描
    test.txt内容：hello shell world!
    myfile="cat test.txt"
    (1)echo $myfile　　#result:cat test.txt
    (2)eval $myfile　　#result:hello shell world!
    从（2）可以知道第一次扫描进行了变量替换，第二次扫描执行了该字符串中所包含的命令

3.通配符

  • [0-9] 取0到9之间的任意一个字符
  • [^0-9] 不是0到9的字符
  • [abc] 取a或者b或者c
  • [a-z] 取字母a-z之间的字符
  • [A-Z] 取字母A-Z之间的字符

? 表示匹配1个字符或者0个

shell 复制代码 
[root@gh-shell 1-18] echo "abc abbc ac"|egrep -o "ab?c"
abc
ac
[root@gh-shell 1-18]#

加号表示，至少要有一个

shell 复制代码 
[root@gh-shell 1-18] echo "abc abbc abbbbc ac"|egrep -o "ab+c"
abc
abbc
abbbbc
[root@gh-shell 1-18]#

{4} 表示前面的字符出现4次

shell 复制代码 
[root@gh-shell 1-18] echo "abc abbc abbbbc ac"|egrep -o "ab{4}c"
abbbbc
[root@gh-shell 1-18]#

{4,}代表 4次及以上

shell 复制代码 
[root@gh-shell 1-18] echo "abc abbc abbbbbbbbc abbbbc ac"|egrep -o "ab{4,}c"
abbbbbbbbc
abbbbc
[root@gh-shell 1-18]#

{4,8}表示4-8之内都可以

{,8}表示0-8都可以 很像切片
(ab){,8} 表示 ab 出现0到8次 ，ab是整体

shell 复制代码 
[root@gh-shell 1-18] echo "abc abbc abbbbbbbbc abbbbc ac"|egrep -o "(ab){,8}c"
abc
c
c
c
c
[root@gh-shell 1-18]#

4.grep

grep和egrep的区别:

grep是基本正则：^ $ . *

egrep是扩展正则: | + ? {} --->支持更多的元字符

-i: 不区分大小写

shell 复制代码 
[root@gh-shell 1-18] cat mobile_phone.txt 
xiaomi HUAWEI
oppo VIVO vivo
huawei apple
sanxin > 123
XIAOMI DAMI
LG lenovo nokia NOKIA
12345 sanchaung
oneplus 2345 #$


[root@gh-shell 1-18] cat mobile_phone.txt |egrep "xiaomi"
xiaomi HUAWEI

[root@gh-shell 1-18] cat mobile_phone.txt |egrep  -i "xiaomi"
xiaomi HUAWEI
XIAOMI DAMI

[root@gh-shell 1-18] cat mobile_phone.txt |egrep  -i "xiaomi|huawei"
xiaomi HUAWEI
huawei apple
XIAOMI DAMI

  • ^ 表示以什么开头

  • $表示以什么结尾

-E 就是扩展正则，相当于egrep

-n 是编号，出现在文本的第几行

shell 复制代码 
[root@gh-shell 1-18] cat mobile_phone.txt |egrep -n -i "xiaomi|huawei"
1:xiaomi HUAWEI
3:huawei apple
5:XIAOMI DAMI
[root@gh-shell 1-18]#

-o only-match 仅仅匹配符合要求的行

shell 复制代码 
[root@gh-shell 1-18] cat mobile_phone.txt |egrep -n -o -i "xiaomi|huawei"
1:xiaomi
1:HUAWEI
3:huawei
5:XIAOMI
[root@gh-shell 1-18]#
shell 复制代码 
[root@gh-shell 1-18] cat /etc/passwd|grep -o root #查找所有包含root的行
root
root
root
root
root
root
root
root
root
[root@gh-shell 1-18] cat /etc/passwd|grep -o root|wc -l
9
[root@gh-shell 1-18]#

-v取反的意思(整行取反)

区别[^] 这个是单字符取反

shell 复制代码 
[root@gh-shell 1-18] cat /etc/passwd|grep -v root

-c 满足要求的行的次数

shell 复制代码 
[root@gh-shell 1-18] cat mobile_phone.txt |grep -c -i "xiaomi"
2
[root@gh-shell 1-18]#

-A 找出符合要求的后面的行数

shell 复制代码 
[root@gh-shell 1-18] cat mobile_phone.txt |egrep -A 3 vivo
oppo VIVO vivo
huawei apple
sanxin > 123
XIAOMI DAMI

-C 找出符合要求的上下n行

shell 复制代码 
[root@gh-shell 1-18] cat mobile_phone.txt |egrep -C 2 apple
xiaomi HUAWEI
oppo VIVO vivo
huawei apple
sanxin > 123
XIAOMI DAMI
[root@gh-shell 1-18]#

-r递归查找 后边接的是文件夹

shell 复制代码 
[root@gh-shell 1-18] egrep "xiaomi" -r /shell
/shell/1-18/mobile_phone.txt:xiaomi HUAWEI
/shell/1-18/gao.txt:xiaomi dami
[root@gh-shell 1-18]#

\<:表示词首部 表示以这个单词开头

\<abc\>: 表示abc这个单词

\< 或者 \>符合 可以用 \b来表示 单词的边界

shell 复制代码 
[root@gh-shell 1-18] echo "chenjinhuai chenjinjin chenjingui"|egrep "jin\b"
chenjinhuai chenjinjin chenjingui
[root@gh-shell 1-18]#
shell 复制代码 
'表示单词以chen开头'
[root@gh-shell 1-18] echo "chenjinhuai chenjinjin chenjingui"|egrep "\<chen"
chenjinhuai chenjinjin chenjingui
[root@gh-shell 1-18]# 

'只找chenjinhuai这个单词'
[root@gh-shell 1-18] echo "chenjinhuai chenjinjin chenjingui"|egrep "\<chenjinhuai\>"
chenjinhuai chenjinjin chenjingui
[root@gh-shell 1-18]# 

'找单词以gui结尾的'
[root@gh-shell 1-18] echo "chenjinhuai chenjinjin chenjingui"|egrep "gui\>"
chenjinhuai chenjinjin chenjingui
[root@gh-shell 1-18]#

5.正则表达式的普通内容

shell 复制代码 
[root@gh-shell 1-18] echo aaabbbcc|egrep "b*"
aaabbbcc
[root@gh-shell 1-18]# 

[root@gh-shell 1-18] cat mobile_phone.txt |egrep  -n "^huawei$"
9:huawei
[root@gh-shell 1-18] cat mobile_phone.txt |egrep  -n "^$"
11:
12:
13:
[root@gh-shell 1-18]#

取反，显示行号，匹配空行，以#开头

shell 复制代码 
[root@gh-shell 1-18] cat /etc/ssh/sshd_config|egrep  -n -v "^$|^#"

.代表单个任意字符

shell 复制代码 
[root@gh-shell 1-18] cat /etc/passwd|egrep "^sc....:"
sc10:x:1009:1009::/home/sc10:/bin/bash
sc11:x:1010:1010::/home/sc11:/bin/bash
sc12:x:1011:1011::/home/sc12:/bin/bash
sc13:x:1012:1012::/home/sc13:/bin/bash
sc14:x:1013:1013::/home/sc14:/bin/bash
sc15:x:1014:1014::/home/sc15:/bin/bash
sc16:x:1015:1015::/home/sc16:/bin/bash
sc17:x:1016:1016::/home/sc17:/bin/bash
sc18:x:1017:1017::/home/sc18:/bin/bash
sc19:x:1018:1018::/home/sc19:/bin/bash
sc20:x:1019:1019::/home/sc20:/bin/bash
[root@gh-shell 1-18]#

任意内容:

shell 复制代码 
[root@gh-shell 1-18] cat /etc/passwd|egrep "^sc.*:"
sc1:x:1000:1000::/home/sc1:/bin/bash
sc2:x:1001:1001::/home/sc2:/bin/bash
sc3:x:1002:1002::/home/sc3:/bin/bash
sc4:x:1003:1003::/home/sc4:/bin/bash
sc5:x:1004:1004::/home/sc5:/bin/bash
sc6:x:1005:1005::/home/sc6:/bin/bash
sc7:x:1006:1006::/home/sc7:/bin/bash
sc8:x:1007:1007::/home/sc8:/bin/bash
sc9:x:1008:1008::/home/sc9:/bin/bash
sc10:x:1009:1009::/home/sc10:/bin/bash
sc11:x:1010:1010::/home/sc11:/bin/bash
sc12:x:1011:1011::/home/sc12:/bin/bash
sc13:x:1012:1012::/home/sc13:/bin/bash
sc14:x:1013:1013::/home/sc14:/bin/bash
sc15:x:1014:1014::/home/sc15:/bin/bash
sc16:x:1015:1015::/home/sc16:/bin/bash
sc17:x:1016:1016::/home/sc17:/bin/bash
sc18:x:1017:1017::/home/sc18:/bin/bash
sc19:x:1018:1018::/home/sc19:/bin/bash
sc20:x:1019:1019::/home/sc20:/bin/bash
[root@gh-shell 1-18]#

6.一些问题

怎么找出特殊字符

shell 复制代码 
[root@gh-shell 1-18] cat mobile_phone.txt |egrep "[^0-Z]"
xiaomi HUAWEI
oppo VIVO vivo
huawei apple
sanxin > 123
XIAOMI DAMI
LG lenovo nokia NOKIA
12345 sanchaung
oneplus 2345 #$
[root@gh-shell 1-18] cat mobile_phone.txt |egrep "[^0-9a-zA-Z]"
xiaomi HUAWEI
oppo VIVO vivo
huawei apple
sanxin > 123
XIAOMI DAMI
LG lenovo nokia NOKIA
12345 sanchaung
oneplus 2345 #$
[root@gh-shell 1-18]#

怎么知道字符串的长度

shell 复制代码 
[root@gh-shell 1-18] u_pwd="asfasfafasdfgefdgae"
[root@gh-shell 1-18] echo ${#u_pwd}
19

[root@gh-shell 1-18] echo $u_pwd|wc -L
19
[root@gh-shell 1-18]#

判断用户的密码里是否有特殊字符

shell 复制代码 
[root@gh-shell 1-18] echo ${u_pwd}|egrep "[0-9]"|egrep "[A-Z]"|egrep "[^0-Z]"
asfasfafasdfgefdgae1$&FGTT
[root@gh-shell 1-18]#

判断用户密码是否符合复杂性要求

shell 复制代码 
[root@gh-shell 1-18] cat user_passwd.sh 
#!/bin/bash

#将第一个位置变量的内容复制给 u_pwd
u_pwd=$1

#判断密码的长度
pwd_l=${#u_pwd}

#判断长度是否大于8
if (( $pwd_l >=8 ));then
	#判断是否包含数字，大写，特殊符合
	if echo $u_pwd|egrep "[0-9]"|egrep "[A-Z]"|egrep "[^0-Z]" &>/dev/null;then
		echo "密码满足复杂性要求"
	else
		echo "密码不满足复杂性要求"
	fi
else
	echo "密码长度小于8，请重新输入"
fi
[root@gh-shell 1-18]#

7.作业

1.查找 var/log/messages 这个文件里单词的长度在16-18之间的单词显示出来

shell 复制代码 
[root@gh-shell 1-18] cat /var/log/messages|egrep "\<[a-Z]{16,18}\>"

2.进入/lianxi目录，复制/etc/passwd到当前目录下，然后对passwd进行操作

shell 复制代码 
[root@gh-shell 1-18] cd /lianxi/
[root@gh-shell lianxi] cp /etc/passwd .
[root@gh-shell lianxi]#

3、查找出当前passwd文件中以ftp或者mail开头的行，在屏幕上输出。

shell 复制代码 
[root@gh-shell lianxi] cat passwd |egrep "^ftp|^mail"
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
[root@gh-shell lianxi]#

4、查找出当前passwd文件中首行不是以r、m、f开头的行，在屏幕上输出。

shell 复制代码 
[root@gh-shell lianxi] cat passwd |egrep -v "^r|^m|^f"
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
polkitd:x:999:998:User for polkitd:/:/sbin/nologin
tss:x:59:59:Account used by the trousers package to sandbox the tcsd daemon:/dev/null:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
chrony:x:998:996::/var/lib/chrony:/sbin/nologin
sc1:x:1000:1000::/home/sc1:/bin/bash
sc2:x:1001:1001::/home/sc2:/bin/bash
sc3:x:1002:1002::/home/sc3:/bin/bash
sc4:x:1003:1003::/home/sc4:/bin/bash
sc5:x:1004:1004::/home/sc5:/bin/bash
sc6:x:1005:1005::/home/sc6:/bin/bash
sc7:x:1006:1006::/home/sc7:/bin/bash
sc8:x:1007:1007::/home/sc8:/bin/bash
sc9:x:1008:1008::/home/sc9:/bin/bash
sc10:x:1009:1009::/home/sc10:/bin/bash
sc11:x:1010:1010::/home/sc11:/bin/bash
sc12:x:1011:1011::/home/sc12:/bin/bash
sc13:x:1012:1012::/home/sc13:/bin/bash
sc14:x:1013:1013::/home/sc14:/bin/bash
sc15:x:1014:1014::/home/sc15:/bin/bash
sc16:x:1015:1015::/home/sc16:/bin/bash
sc17:x:1016:1016::/home/sc17:/bin/bash
sc18:x:1017:1017::/home/sc18:/bin/bash
sc19:x:1018:1018::/home/sc19:/bin/bash
sc20:x:1019:1019::/home/sc20:/bin/bash
[root@gh-shell lianxi]#

5、查找出当前passwd文件中以bash结尾的行。

shell 复制代码 
[root@gh-shell lianxi] cat passwd |egrep  "bash$"
root:x:0:0:root:/root:/bin/bash
sc1:x:1000:1000::/home/sc1:/bin/bash
sc2:x:1001:1001::/home/sc2:/bin/bash
sc3:x:1002:1002::/home/sc3:/bin/bash
sc4:x:1003:1003::/home/sc4:/bin/bash
sc5:x:1004:1004::/home/sc5:/bin/bash
sc6:x:1005:1005::/home/sc6:/bin/bash
sc7:x:1006:1006::/home/sc7:/bin/bash
sc8:x:1007:1007::/home/sc8:/bin/bash
sc9:x:1008:1008::/home/sc9:/bin/bash
sc10:x:1009:1009::/home/sc10:/bin/bash
sc11:x:1010:1010::/home/sc11:/bin/bash
sc12:x:1011:1011::/home/sc12:/bin/bash
sc13:x:1012:1012::/home/sc13:/bin/bash
sc14:x:1013:1013::/home/sc14:/bin/bash
sc15:x:1014:1014::/home/sc15:/bin/bash
sc16:x:1015:1015::/home/sc16:/bin/bash
sc17:x:1016:1016::/home/sc17:/bin/bash
sc18:x:1017:1017::/home/sc18:/bin/bash
sc19:x:1018:1018::/home/sc19:/bin/bash
sc20:x:1019:1019::/home/sc20:/bin/bash
root1:x:1020:1020::/home/root1:/bin/bash
[root@gh-shell lianxi]#

6、查找出/etc/login.defs文件中的有效行（不显示空行和注释行）。

shell 复制代码 
[root@gh-shell lianxi] cat /etc/login.defs |egrep -v "^$|^#"
MAIL_DIR	/var/spool/mail
PASS_MAX_DAYS	99999
PASS_MIN_DAYS	0
PASS_MIN_LEN	5
PASS_WARN_AGE	7
UID_MIN                  1000
UID_MAX                 60000
SYS_UID_MIN               201
SYS_UID_MAX               999
GID_MIN                  1000
GID_MAX                 60000
SYS_GID_MIN               201
SYS_GID_MAX               999
CREATE_HOME	yes
UMASK           077
USERGROUPS_ENAB yes
ENCRYPT_METHOD SHA512
[root@gh-shell lianxi]#

7、查找出/var/log/messages文档中有16个字母的单词？

shell 复制代码 
[root@gh-shell lianxi] cat /var/log/messages|egrep "\b[a-Z]{16}\b"

8、查找出来/etc/passwd文件里用户名包含liu同时使用bash的用户

shell 复制代码 
[root@gh-shell lianxi]  cat /etc/passwd|egrep ".*liu.*:x.*/bin/bash"
liu:x:1022:1022::/home/liu:/bin/bash
liu1:x:1023:1023::/home/liu1:/bin/bash
liu2:x:1024:1024::/home/liu2:/bin/bash
liu3:x:1025:1025::/home/liu3:/bin/bash
[root@gh-shell lianxi]#

9、查找/etc/ssh/sshd_config 里的有效行

shell 复制代码 
[root@gh-shell lianxi] cat /etc/ssh/sshd_config |egrep  -v "^$|^#"
HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_ecdsa_key
HostKey /etc/ssh/ssh_host_ed25519_key
SyslogFacility AUTHPRIV
AuthorizedKeysFile	.ssh/authorized_keys
PasswordAuthentication yes
ChallengeResponseAuthentication no
GSSAPIAuthentication yes
GSSAPICleanupCredentials no
UsePAM yes
X11Forwarding yes
AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES
AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT
AcceptEnv LC_IDENTIFICATION LC_ALL LANGUAGE
AcceptEnv XMODIFIERS
Subsystem	sftp	/usr/libexec/openssh/sftp-server
[root@gh-shell lianxi]#

10、查找出/etc/ssh/sshd_config 文件里的包含连续2个数字的行

shell 复制代码 
[root@gh-shell lianxi] cat /etc/ssh/sshd_config |egrep "\b[0-9]{2}\b"
#	$OpenBSD: sshd_config,v 1.100 2016/08/15 12:32:04 naddy Exp $
#Port 22
#MaxSessions 10
#X11DisplayOffset 10
#MaxStartups 10:30:100
[root@gh-shell lianxi]#

11、查找出包含特殊字符的行

shell 复制代码 
[root@gh-shell lianxi] cat /etc/ssh/sshd_config |egrep "[^0-Z]"
#	$OpenBSD: sshd_config,v 1.100 2016/08/15 12:32:04 naddy Exp $
# This is the sshd server system-wide configuration file.  See
# sshd_config(5) for more information.
# This sshd was compiled with PATH=/usr/local/bin:/usr/bin
# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented.  Uncommented options override the
# default value.
# If you want to change the port on a SELinux system, you have to tell
# SELinux about this change.
# semanage port -a -t ssh_port_t -p tcp #PORTNUMBER
#
#Port 22
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::
HostKey /etc/ssh/ssh_host_rsa_key
#HostKey /etc/ssh/ssh_host_dsa_key
HostKey /etc/ssh/ssh_host_ecdsa_key
HostKey /etc/ssh/ssh_host_ed25519_key
# Ciphers and keying
#RekeyLimit default none
# Logging
#SyslogFacility AUTH
SyslogFacility AUTHPRIV
#LogLevel INFO
# Authentication:
#LoginGraceTime 2m
#PermitRootLogin yes
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10
#PubkeyAuthentication yes
# The default is to check both .ssh/authorized_keys and .ssh/authorized_keys2
# but this is overridden so installations will only check .ssh/authorized_keys
AuthorizedKeysFile	.ssh/authorized_keys
#AuthorizedPrincipalsFile none
#AuthorizedKeysCommand none
#AuthorizedKeysCommandUser nobody
# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
#HostbasedAuthentication no
# Change to yes if you don't trust ~/.ssh/known_hosts for
# HostbasedAuthentication
#IgnoreUserKnownHosts no
# Don't read the user's ~/.rhosts and ~/.shosts files
#IgnoreRhosts yes
# To disable tunneled clear text passwords, change to no here!
#PasswordAuthentication yes
#PermitEmptyPasswords no
PasswordAuthentication yes
# Change to no to disable s/key passwords
#ChallengeResponseAuthentication yes
ChallengeResponseAuthentication no
# Kerberos options
#KerberosAuthentication no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes
#KerberosGetAFSToken no
#KerberosUseKuserok yes
# GSSAPI options
GSSAPIAuthentication yes
GSSAPICleanupCredentials no
#GSSAPIStrictAcceptorCheck yes
#GSSAPIKeyExchange no
#GSSAPIEnablek5users no
# Set this to 'yes' to enable PAM authentication, account processing,
# and session processing. If this is enabled, PAM authentication will
# be allowed through the ChallengeResponseAuthentication and
# PasswordAuthentication.  Depending on your PAM configuration,
# PAM authentication via ChallengeResponseAuthentication may bypass
# the setting of "PermitRootLogin without-password".
# If you just want the PAM account and session checks to run without
# PAM authentication, then enable this but set PasswordAuthentication
# and ChallengeResponseAuthentication to 'no'.
# WARNING: 'UsePAM no' is not supported in Red Hat Enterprise Linux and may cause several
# problems.
UsePAM yes
#AllowAgentForwarding yes
#AllowTcpForwarding yes
#GatewayPorts no
X11Forwarding yes
#X11DisplayOffset 10
#X11UseLocalhost yes
#PermitTTY yes
#PrintMotd yes
#PrintLastLog yes
#TCPKeepAlive yes
#UseLogin no
#UsePrivilegeSeparation sandbox
#PermitUserEnvironment no
#Compression delayed
#ClientAliveInterval 0
#ClientAliveCountMax 3
#ShowPatchLevel no
#UseDNS yes
#PidFile /var/run/sshd.pid
#MaxStartups 10:30:100
#PermitTunnel no
#ChrootDirectory none
#VersionAddendum none
# no default banner path
#Banner none
# Accept locale-related environment variables
AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES
AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT
AcceptEnv LC_IDENTIFICATION LC_ALL LANGUAGE
AcceptEnv XMODIFIERS
# override default of no subsystems
Subsystem	sftp	/usr/libexec/openssh/sftp-server
# Example of overriding settings on a per-user basis
#Match User anoncvs
#	X11Forwarding no
#	AllowTcpForwarding no
#	PermitTTY no
#	ForceCommand cvs server
[root@gh-shell lianxi]#

12、查找出不包含数字的行

shell 复制代码 
[root@gh-shell lianxi] cat /etc/ssh/sshd_config |egrep -v "[0-9]"

# This is the sshd server system-wide configuration file.  See

# This sshd was compiled with PATH=/usr/local/bin:/usr/bin

# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented.  Uncommented options override the
# default value.

# If you want to change the port on a SELinux system, you have to tell
# SELinux about this change.
# semanage port -a -t ssh_port_t -p tcp #PORTNUMBER
#
#AddressFamily any
#ListenAddress ::

HostKey /etc/ssh/ssh_host_rsa_key
#HostKey /etc/ssh/ssh_host_dsa_key
HostKey /etc/ssh/ssh_host_ecdsa_key

# Ciphers and keying
#RekeyLimit default none

# Logging
#SyslogFacility AUTH
SyslogFacility AUTHPRIV
#LogLevel INFO

# Authentication:

#PermitRootLogin yes
#StrictModes yes

#PubkeyAuthentication yes

# but this is overridden so installations will only check .ssh/authorized_keys
AuthorizedKeysFile	.ssh/authorized_keys

#AuthorizedPrincipalsFile none

#AuthorizedKeysCommand none
#AuthorizedKeysCommandUser nobody

# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
#HostbasedAuthentication no
# Change to yes if you don't trust ~/.ssh/known_hosts for
# HostbasedAuthentication
#IgnoreUserKnownHosts no
# Don't read the user's ~/.rhosts and ~/.shosts files
#IgnoreRhosts yes

# To disable tunneled clear text passwords, change to no here!
#PasswordAuthentication yes
#PermitEmptyPasswords no
PasswordAuthentication yes

# Change to no to disable s/key passwords
#ChallengeResponseAuthentication yes
ChallengeResponseAuthentication no

# Kerberos options
#KerberosAuthentication no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes
#KerberosGetAFSToken no
#KerberosUseKuserok yes

# GSSAPI options
GSSAPIAuthentication yes
GSSAPICleanupCredentials no
#GSSAPIStrictAcceptorCheck yes
#GSSAPIKeyExchange no

# Set this to 'yes' to enable PAM authentication, account processing,
# and session processing. If this is enabled, PAM authentication will
# be allowed through the ChallengeResponseAuthentication and
# PasswordAuthentication.  Depending on your PAM configuration,
# PAM authentication via ChallengeResponseAuthentication may bypass
# the setting of "PermitRootLogin without-password".
# If you just want the PAM account and session checks to run without
# PAM authentication, then enable this but set PasswordAuthentication
# and ChallengeResponseAuthentication to 'no'.
# WARNING: 'UsePAM no' is not supported in Red Hat Enterprise Linux and may cause several
# problems.
UsePAM yes

#AllowAgentForwarding yes
#AllowTcpForwarding yes
#GatewayPorts no
#PermitTTY yes
#PrintMotd yes
#PrintLastLog yes
#TCPKeepAlive yes
#UseLogin no
#UsePrivilegeSeparation sandbox
#PermitUserEnvironment no
#Compression delayed
#ShowPatchLevel no
#UseDNS yes
#PidFile /var/run/sshd.pid
#PermitTunnel no
#ChrootDirectory none
#VersionAddendum none

# no default banner path
#Banner none

# Accept locale-related environment variables
AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES
AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT
AcceptEnv LC_IDENTIFICATION LC_ALL LANGUAGE
AcceptEnv XMODIFIERS

# override default of no subsystems
Subsystem	sftp	/usr/libexec/openssh/sftp-server

# Example of overriding settings on a per-user basis
#Match User anoncvs
#	AllowTcpForwarding no
#	PermitTTY no
#	ForceCommand cvs server
[root@gh-shell lianxi]#

13、查找出/var/log/secure里的ip地址出来

shell 复制代码 
[root@gh-shell lianxi] cat /var/log/secure|egrep "[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}"
Jan 17 15:46:23 gh-shell sshd[5760]: Address 192.168.153.1 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Jan 17 15:46:23 gh-shell sshd[5760]: Accepted password for root from 192.168.153.1 port 59386 ssh2
Jan 17 15:46:25 gh-shell sshd[5781]: Address 192.168.153.1 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Jan 17 15:46:25 gh-shell sshd[5781]: Accepted password for root from 192.168.153.1 port 59387 ssh2
Jan 18 08:28:36 gh-shell sshd[6481]: Address 192.168.153.1 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Jan 18 08:28:36 gh-shell sshd[6481]: Accepted password for root from 192.168.153.1 port 64503 ssh2
Jan 18 08:28:39 gh-shell sshd[6502]: Address 192.168.153.1 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Jan 18 08:28:39 gh-shell sshd[6502]: Accepted password for root from 192.168.153.1 port 64504 ssh2
[root@gh-shell lianxi]# cat /var/log/secure|egrep "([0-9]{1,3}\.){3}[0-9]{1,3}"
Jan 17 15:46:23 gh-shell sshd[5760]: Address 192.168.153.1 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Jan 17 15:46:23 gh-shell sshd[5760]: Accepted password for root from 192.168.153.1 port 59386 ssh2
Jan 17 15:46:25 gh-shell sshd[5781]: Address 192.168.153.1 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Jan 17 15:46:25 gh-shell sshd[5781]: Accepted password for root from 192.168.153.1 port 59387 ssh2
Jan 18 08:28:36 gh-shell sshd[6481]: Address 192.168.153.1 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Jan 18 08:28:36 gh-shell sshd[6481]: Accepted password for root from 192.168.153.1 port 64503 ssh2
Jan 18 08:28:39 gh-shell sshd[6502]: Address 192.168.153.1 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Jan 18 08:28:39 gh-shell sshd[6502]: Accepted password for root from 192.168.153.1 port 64504 ssh2
[root@gh-shell lianxi]# cat /var/log/secure|egrep "([0-9]{1,3}\.){3}[0-9]{1,3}"
Jan 17 15:46:23 gh-shell sshd[5760]: Address 192.168.153.1 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Jan 17 15:46:23 gh-shell sshd[5760]: Accepted password for root from 192.168.153.1 port 59386 ssh2
Jan 17 15:46:25 gh-shell sshd[5781]: Address 192.168.153.1 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Jan 17 15:46:25 gh-shell sshd[5781]: Accepted password for root from 192.168.153.1 port 59387 ssh2
Jan 18 08:28:36 gh-shell sshd[6481]: Address 192.168.153.1 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Jan 18 08:28:36 gh-shell sshd[6481]: Accepted password for root from 192.168.153.1 port 64503 ssh2
Jan 18 08:28:39 gh-shell sshd[6502]: Address 192.168.153.1 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Jan 18 08:28:39 gh-shell sshd[6502]: Accepted password for root from 192.168.153.1 port 64504 ssh2
[root@gh-shell lianxi]#

14、写一个表示下面网址的正则表达式出来。

例如： http://www.baidu.com

http://www.sina.com

http://www.163.com

http://www.12306.cn

http://www.qillu.edu

shell 复制代码 
[root@gh-shell lianxi] cat web.txt|egrep "[a-Z]+://([0-Z]+\.){2}[0-Z]+" 
http://www.baidu.com
http://www.sina.com
http://www.163.com
http://www.12306.cn 
http://www.qillu.edu

15、写一个表示下面网址的正则表达式出来。

例如： http://www.baidu.com

http://www.sina.com

http://www.163.com

http://www.12306.cn

http://www.qillu.edu

rsync://www.github.com/abc

ftp://192.168.0.1

ftp://www.baidu.com

shell 复制代码 
[root@gh-shell lianxi] cat web2.txt|egrep "[a-Z]+://([0-Z]+\.){2}[0-Z]+" 
http://www.baidu.com
http://www.sina.com
http://www.163.com 
http://www.12306.cn 
http://www.qillu.edu 
rsync://www.github.com/abc 
ftp://192.168.0.1 
ftp://www.baidu.com 
[root@gh-shell lianxi]#

16、写一个表示邮箱的正则

feng@qq.com

1234feng@163.com

meng.xianhui@yahoo.cn

liudehua@sina.com

10001@qq.com

123_ui@12306.cn

qilu@qilu.edu

qilu@qilu.edu/fjdkfjk/fjdk

shell 复制代码 
[root@gh-shell lianxi] cat mail.txt|egrep "[0-Z_]+@[0-Z]+\.[a-z]+"
feng@qq.com 
1234feng@163.com
meng.xianhui@yahoo.cn
liudehua@sina.com 
10001@qq.com 
123_ui@12306.cn 
qilu@qilu.edu 
qilu@qilu.edu/fjdkfjk/fjdk
[root@gh-shell lianxi]#

17、C类ip地址的正则表达式 section1:范围在192-223之间 section2和section3和section4范围：0-255之间

例如：193.168.23.1

shell 复制代码 
[root@gh-shell lianxi] cat /var/log/secure|egrep "\b(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9])\b"
Jan 17 15:46:23 gh-shell sshd[5760]: Address 192.168.153.1 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Jan 17 15:46:23 gh-shell sshd[5760]: Accepted password for root from 192.168.153.1 port 59386 ssh2
Jan 17 15:46:25 gh-shell sshd[5781]: Address 192.168.153.1 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Jan 17 15:46:25 gh-shell sshd[5781]: Accepted password for root from 192.168.153.1 port 59387 ssh2
Jan 18 08:28:36 gh-shell sshd[6481]: Address 192.168.153.1 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Jan 18 08:28:36 gh-shell sshd[6481]: Accepted password for root from 192.168.153.1 port 64503 ssh2
Jan 18 08:28:39 gh-shell sshd[6502]: Address 192.168.153.1 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Jan 18 08:28:39 gh-shell sshd[6502]: Accepted password for root from 192.168.153.1 port 64504 ssh2
[root@gh-shell lianxi]#

A: 1~127

B:128~191

C:192~223

1位数字

0-9
2位数

10~99
3位数

100~199

200~249

250~255

shell 复制代码 
'4个255的正则'
\b(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9])\b
shell 复制代码 
'B类:128~191'
(12[89]|1[3-8][0-9]|19[01])(\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])){3}
shell 复制代码 
'A类:1~127'
([1-9]|[1-9][0-9]|11[0-9]|12[0-7])(\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])){3}
[root@gh-shell lianxi] cat /var/log/secure|egrep "\b([1-9]|[1-9][0-9]|11[0-9]|12[0-7])(\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])){3}\b"
1.12.34.5
2.12.34.5
88.12.34.5
[root@gh-shell lianxi]#

18.用简单的正则匹配 netstat -antplu 的ip地址，去重

shell 复制代码 
[root@gh-shell lianxi] netstat -antplu|egrep -o "\b(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9])\b"|sort|uniq
0.0.0.0
127.0.0.1
192.168.153.1
192.168.153.161
[root@gh-shell lianxi]#

19.用shell生成 16位的密码

shell 复制代码 
[root@gh-shell lianxi] echo "$RANDOM"|md5sum|cut -c 1-16
97e41756d502e1e6
[root@gh-shell lianxi]#

20.使用ps命令查看进程(pid=2345)的启动时间

shell 复制代码 
[root@gh-shell lianxi] ps aux|awk '$2 == 23 {print $0}'
root         23  0.0  0.0      0     0 ?        S    1月17   0:00 [migration/3]
[root@gh-shell lianxi] ps aux|awk '$2 == 23 {print $9}'
1月17
[root@gh-shell lianxi]#
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