Linux Basic optimization

LinuxCommand Optimization1th Chapter 13Supplementary Questions

in the/oldboy directory and its subdirectories, all files that end with the extension. SH are replaced with a string that contains Oldboy. Oldgirl

1.1Method1

[Email protected] ~]# find/oldboy/-type f-name "*.sh"

/oldboy/test/del.sh

/oldboy/test.sh

/oldboy/t.sh

[Email protected] ~]# find/oldboy/-type f-name "*.sh" |xargs ls-l

-rw-r--r--. 1 root root 8 Jul 17:48/oldboy/test/del.sh

-rw-r--r--. 1 root root 8 Jul 17:48/oldboy/test.sh

-rw-r--r--. 1 root root 8 Jul 17:48/oldboy/t.sh

1.2Method2

Ready Posture

[Email protected] ~]# which mkdir

/bin/mkdir

[Email protected] ~]# ll/bin/mkdir

-rwxr-xr-x. 1 root root 50056 Mar 2017/bin/mkdir

[Email protected] ~]# ll which mkdir

Ls:cannot access which:no such file or directory

Ls:cannot access mkdir:no such file or directory

[[email protected] ~]# ll $ (which mkdir)

-rwxr-xr-x. 1 root root 50056 Mar 2017/bin/mkdir

#$()  run the command inside the parentheses first and then execute the other commands.

#$()   `` Anti-Quote

find/oldboy/-type f-name "*.sh" and Ls-l

ll $ (find/oldboy/-type f-name "*.sh")

1.3Method3

[Email protected] ~]# find/oldboy/-type f-name "*.sh"-exec ls-l {} \;

-rw-r--r--. 1 root root 8 Jul 17:48/oldboy/test/del.sh

-rw-r--r--. 1 root root 8 Jul 17:48/oldboy/test.sh

-rw-r--r--. 1 root root 8 Jul 17:48/oldboy/t.sh

Summary:

Find command to find the file to give to other commands (LS sed rm)

1 , find/oldboy/-type f-name "*.sh" |xargs ls-l

2 , LL $ (find/oldboy/-type f-name "*.sh")

3 , find/oldboy/-type f-name "*.sh"-exec ls-l {} \;

2nd Chapter |with the|xargsdifference

| Piping Pass the previous command result through a pipeline to a later command passing text text

|xargs turn the previous command result passing through a pipeline to a later command The file name is passed

[Email protected] ~]# sed-i ' s#old#young#g '

Sed:no input Files

[Email protected] ~]# find/oldboy/-type f-name "*.sh"

/oldboy/test/del.sh

/oldboy/test.sh

/oldboy/t.sh

[Email protected] ~]# find/oldboy/-type f-name "*.sh" |sed-i ' s#old#you#g '

Sed:no input Files

[Email protected] ~]# find/oldboy/-type f-name "*.sh" |xargs sed-i ' s#old#you#g '

#find +|xargs

3rd Chapter PS13.1Environment Variables

variables

x + y = ten, known x=11 y=?

Environment variables

1. Uppercase

2. Can be used in most parts of the system meaning basically unchanged

3. System creation

PS1 ===== Martial Arts cheats (sunflower Treasure)

echo $PS 1 ===== reading

Ps1= ' [\[email protected]\h \w]\$ ' ===== write content " if you want to practice this work, you will be able to succeed from the palace."

3.2 PS1control command line appearance3.2.1 #Temporary

Export ps1= ' [\[email protected]\h \w]\$ '

3.2.2 #Permanent

Vim/etc/profile #编辑文件

[Email protected]/data]# tail-2/etc/profile

Alias net= ' Cat/etc/sysconfig/network-scripts/ifcfg-eth0 '

Export ps1= ' [\[email protected]\h \w]\$ '

#生效

Source/etc/profile

Summary:

1. characteristics of environmental variables

2. View environment variable contents

4th Chapter # #SElinux

NSA

4.1CloseSElinux

4.1.1permanently closedSElinux-takes effect after server restart

/etc/selinux/config

# selinux= can take one of these three values:

# Enforcing default SELinux open in Run

# permissive SELinux shutdown warning message

# disabled SELinux completely shut down

Selinux=enforcing

Don't give yourself any reason to restart the server

Vim

U

C Delete the cursor to the end of the line and enter edit mode

4.1.2temporarily closedselinux–

[Email protected] ~]# getenforce

Enforcing

[Email protected] ~]# setenforce

Usage:setenforce [Enforcing | Permissive | 1 | 0]

[Email protected] ~]# setenforce 0

[Email protected] ~]# getenforce

Permissive

4.1.3CloseSElinux:

Pre-operation backup, post-operation check

0. Backup

1. Temporary

2. Permanent

3. Check

esc+. ( dot ) Use the last thing on the previous command

5th Chapter SEDmodify files and back up

[Email protected]/oldboy]# cat t.sh

Yougirl

[[email protected]/oldboy]# sed ' s#girl#boy#g ' t.sh

Youboy

[Email protected]/oldboy]# sed-i.bak ' s#girl#boy#g ' t.sh

[[email protected]/oldboy]# #-i.bak first back up the file T.sh.bak

[[Email protected]/oldboy]# # then modify the contents of the file

[Email protected]/oldboy]# cat t.sh

Youboy

[Email protected]/oldboy]# cat T.sh.bak

Yougirl

CentOS 5.x 6.x Firewall iptables

CentOS 7.x FIREWALLD

Work application:

Firewall Server has public IP address Open

Firewall Server only intranet IP address off

when it's high concurrency,

5.1CloseIptables 5.1.1 #1.Temporary

[[email protected]/oldboy]# /etc/init.d/iptables Stop

Iptables:setting chains to Policy Accept:filter [OK]

iptables:flushing firewall rules: [OK]

iptables:unloading modules: [OK]

[[email protected]/oldboy]# /etc/init.d/iptables Stop

[Email protected]/oldboy]# /etc/init.d/iptables status

Iptables:firewall is not running.

5.1.2 #2.permanently closed-

Turn off boot from The software runs automatically at boot time

post-boot software management commands

[Email protected]/oldboy]# chkconfig iptables off

[Email protected]/oldboy]# chkconfig |grep IPT

Iptables 0:off 1:off 2:off 3:off 4:off 5:off 6:off

6th ChapterCloseIptablesSummary:6.1Temporary-failed after restarting server

/etc/init.d/iptables stop

6.2.Permanent-takes effect after restarting the server

# turn off boot from start

chkconfig iptables off

6.3Check

/etc/init.d/iptables status

Chkconfig |grep IPT

GBK National Standard

UTF-8 Universal Code

6.3.1View Character Sets

[Email protected]/oldboy]# echo $LANG

en_US. UTF-8

[[email protected]/oldboy]# #en_US language

[[email protected]/oldboy]# #UTF-8 Character Set

[Email protected]/oldboy]# #语言. Character Set

6.3.2.Modifying character sets-Temporary

[[email protected]/oldboy]# export. UTF-8

[Email protected]/oldboy]# echo $LANG

Zh_cn. UTF-8

6.3.3permanently modify character sets

[Email protected]/oldboy]# cat/etc/sysconfig/i18n

Lang= "en_US. UTF-8 "

Sysfont= "Latarcyrheb-sun16"

[Email protected]/oldboy]# source/etc/sysconfig/i18n

[Email protected]/oldboy]# echo $LANG

en_US. UTF-8

Linux display in Chinese garbled:

the character set of the 1.linux system is different from the Remote connection tool

Summary:

1.find command to find the file to give to other commands (LS rm sed) three kinds

2. environment variable: PS1 LANG (must be modified)

3. Turn off SELinux and Iptables

4. How to modify the character set

Linux Basic optimization