Shell Basics Exercise Notes

1. Turn off unnecessary services
NTSYSV Chkconfig
Services that must be turned on are: CROND/MESSAGEBUS/NETWORK/IPTABLES/SSHD/SYSLOG/SYSSTAT/SNMPD
To close unnecessary service scripts:
For i in ' chkconfig--list |awk '/3:on/{print '} ' |grep-v ' crond\|messagebus\|sshd\|iptables\|network\|syslog\|snmpd\| Sysstat "';
Do chkconfig--level 345 ${i} off;
Done
To open the required service script:
For i in "Crond" "Messagebus" "Iptables" "Network" "SNMPD" "sshd" "Syslog" "Sysstat";
Do chkconfig--level 345 ${i} on;
Done
3. Check the basic configuration of the service
Dmidecode | grep "Product" | Head-n 1 Check Server model
Cat/proc/cpuinfo | grep name | cut-f2-d: |uniq-c Check cup signal
free-m | grep Mem | awk ' {print $} '
Ifconfig | grep "inet addr" | Awk-f: ' {print $} ' | awk ' {print '} '
4. System optimization to modify the/etc/sysctl.conf file, Sysctl-p is modified to take effect;
Turn off unnecessary services using NTSYSV; View self-starting service chkconfig;
5. Modify the system's file handle book/etc/security/limits.conf confirm handle allows data ulimit-n
6. Modify the sshd listener port and disable password Authentication login profile/etc/ssh/sshd_config

7. Account security, clear the login rights of users other than the root user

#!/bin/bash

For k in ' cat/etc/passwd | Grep-i "\/bin\/bash" | Grep-v "Root" | cut-d:-f1 ';

Do

Usermod-s/sbin/nologin ${k};

Done

To change the root user password:

echo "xxxxxxxx" >/root/tmp.txt "xxxxxxxx" for the Set password

passwd root--stdin </root/tmp.txt;rm–f/root/tmp.txt

8. View the system's basic information script

#!/bin/bash

Dmidecode | grep "Product" | Head-n 1

Cat/proc/cpuinfo | grep name | Cut-f2-d: | Uniq-c

free-m | grep Mem | awk ' {print $} '

Ifconfig | grep "inet addr" | Awk-f: ' {print $} ' | awk ' {print '} '

Route-n

Cat/etc/issue | Head-n 1

Uname-a

df-h | awk ' {print $1,$2} '

9. Load the EXT4 module

Modprobe EXT4

Lsmod | grep EXT4

Yum-y Install E4fsprogs

10. Statistics of logged-in users

Uptime | Cut-d ', '-F 2 | Sed ' s/^[[:space:]]*//g '

W.H.O. | Wc-l

11. Add User Scripts

#!/bin/bash

ID $ >/dev/null 2>&1

If [$?-eq 0];then

echo "is exsit!"

Else

Useradd $

echo "123456" | passwd--stdin "$" >/dev/null 2>&1

If [$?-eq 0];then

echo "Create seccuss!"

Fi

Fi

12.sed Delete empty lines

Sed '/^$/d ' file

13.sed Delete Spaces at the beginning of a line

Sed-i ' s/^[[:space:]]*//' filename
Sed-i ' s/[[:space:]]*//g ' filename # #删除所有空格
sed s/[[:space:]]//g filename
#sed ' s/^[]*//g ' file
#sed ' s/^ *//g ' file
#sed ' s/^[[:space:]]*//g ' file

#删除所有行尾空字符

Sed-i ' s/[[:blank:]]+$//' filename

15. Delete the first number of rows

Sed-i ' s/^[0-9]*//g ' filename
Sed ' s#^[0-9]{1,} # #g ' filename
Sed ' s#^[0-9]* # #g ' filename

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Shell Basics Exercise Notes