Shell Script Basics

# # # #shell脚本基础 #####

1. Basic Concepts

Purpose: Many instructions are assembled together, circulated, judged

format: Name . SH (with color)

operating Environment : #! /bin/bash

Run File: 1>chmod +x file Direct plus absolute address to make file executable

2> sh file

Reference:

1> Weak reference: "" preserves literal values of all characters in a string, except for $ ' \

2> Strong reference: ' preserves literal values of all characters in a string, and disables all extensions

3> escape: \ Preserves the literal value of the next character,

Bash-x file.sh #查看过程 \

# + + indicates the command executed first

# + indicates the command executed after

# The final result

2. Specific content

###{} reference variable eg

Dd=q

Pp=k

echo ${dd}_$pp Results: Q_k

# # #备份/All things in the mail group

~~~~~~

#!/bin/bash

time=$ (Date +%h:%m:%s)

Mkdir/mnt/mail. $TIME

Find/mnt-group mail-exec CP-RP {}/mnt/mail. $TIME/\;

~~~~~

# # # #新建用户 # #

#!/bin/bash

xuhao= ' wc-l/mnt/username |cut-d ""-F 1 '

For NUM in $ (SEQ 1 1 $XUHAO)

Do

Username= ' Sed-n ${num}p/mnt/username '

passwd= ' Sed-n ${num}p/mnt/passwd '

Useradd $USERNAME

echo $PASSWD | passwd--stdin $USERNAME

Done

~

~

# # #ping数台机器看能否通 # #

~~~~~

For IP in {1..35}

Do

Ping-c1-w1 172.25.254. $IP &>/dev/null && echo 172.25.254. $IP OK | | echo 172.25.254. $IP Error

Done

~~~~

# # #ping任意一台ip # #

~ ~ ~

#!/bin/bash

PING-C1-W1 172.25.254.$1 &>/dev/null && echo 172.25.254.$1 is OK | | Echo 172.25.254.$1 is error

~ ~ ~

# # #ping是否有ip

# # #其他 # # #

Read ""-s (not displayed directly to the CPU) interactive variable

echo $? 0 for normal exit value # Indicates whether the previous command was output correctly

Exit 1 Set the exit value to 1

Test= ""

# # #建立用户 # # #

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# # #if命令 (comparison && can judge Eslf indefinitely) # # #

if + condition

Then + command

else does not meet other commands

Fi (end)

determine if the value of a variable is null "-Z"

determine If the ping is available and determine if there is an IP

~ ~

#!/bin/bash

If

[-Z $*]

Then

echo "Error:you not give me IPAddress"

Else

PING-C1 (one row only)-w1 (which executes 1s) $* () executes the first parameter followed by &>/dev/nul && (correct) echo $* is up | | Echo $* is down

Fi (end)

~ ~

# # # #case # #

and if function basically the same, but the judgment process at the same time judgment, high efficiency

Eg: when the input is Westos output Linux input Linux, the output westos

~~~~~~

Case $ in

Westos)

Echo Linux

;;

Linux

Echo Westos

;;

*)

echo Error

Esac

~ ~ ~

# # # #expect ######

extension:send: Sends a string to the process;

Expect: Accepts a string from a process;

Spawn: Start a new process;

Interact: Allow user interaction;

Yum Install expect

Expect EOF (end)

# # # # #环境变量 # #

User environment variable settings:vim/root/bash_profile--->export PATH export a=1---> Detection: Echo A

system environment variable settings:vim/etc/profile---export path= $PATH:/MNT export a=2

#alias

Eg:alias Xie=vim can open vim temporary method ile Xie method

Long-term setup: vim/etc/bashrc-->alias xi= ' vim '-->SOURCE/ETC/BASHRC

# # # #脚本简写 (function) # # #

#！ /bin/bash

Ifcmd () {

If

[$] #表示函数IFCMD the first and second digits behind

Then

Echo $ is $

Fi

}

Ifcmd-f $ file

Ifcmd-d $ direcotry

Ifcmd-b Block

# # # #end #####

Shell Script Basics