Http://note.youdao.com/share/?id=a9d02257b639c94323c818bc38423919&type=notealias Command Alias:http://note.youdao.com/share/?id=cbcbd1156ab1f0835c4f76131dbf98e2&type=noteView Current User history commands History:http://note.youdao.com/share/?id=e878f9ed7bb7e8849fa57b67dc1eb7f3&type=noteadd a new hard disk and partition: Http://note.youdao.com/share/?id=8cf27602cdce36e1d4160f00e9004b00&type=noteDD if= input file of= output file bs= number of bytes count= options: if= input file Specify source file or source device of= output file specify destination file or target device ba= bytes Specify the number of bytes of input/output at one time. Make a data block count= number specify the number of input/output data block example: [[email protected]]# date; DD If=/dev/zero of=/root/testfile bs=1k count=100000; Date can be viewed by command execution before and after the date time Difference Example 2: We can use this command for data pair test or burn disk [[email protected]]# date; DD If=/dev/cdrom Of=/data/centos6.4-one.iso; Date, so I can do it. CD-ROM burn to/data/for later use and build local Yum source Pipe break: The correct output of command 1 as the operand of command 2 [[Email protected]]# ls | grep Fengtaotao requires that the command in front of the pipe character must have output [[Email protected]]# ll-a | Morp display the output of the ll-a if the command 1 must have the correct output Netstat-an View the function of the netstat command is to display network connections, routing tables, and network interface information to let users know which network connections are in operation. [1] When used without parameters, Netstat displays the active TCP connection. Example: View a few remote connections on the current server [[Email protected]]# Netstat-an | grep "Established" Of course we can just count lines [Email protected]]# netstat-an | grep "established" | Wc-l
grep command:
[[email protected]] #grep [options] ' search content ' file name option:-I: Case-insensitive-N: Show line number-V: Reverse lookup--color=auto: Receive keyword display color Wildcard characters:
| Wildcard characters |
Role |
| ? |
Match an arbitrary character |
| * |
Match 0 or any number of characters, that is, any content can be matched |
| [] |
Matches any one of the characters in the brackets. For example [ABCD] represents any one of the matching ABCD |
| [-] |
Match any one of the characters in the brackets-representing ranges such as [a-z][a-z][0-9] and so on |
| [^] |
Logical non, which means that the match is not a character in brackets, for example [^0-9] represents a character that is not a number |
| ‘‘ |
Single quotes, in single quotes all special characters will be used as text for example: $ @ * etc |
| "" |
Special symbols in double quotes have no meaning, but for $ \ ' Exception call variable values, apply commands, go to symbols, etc. |
| Anti-Quote |
Same as the following $ () For example: Echo ' ls ' or echo $ (LS) output is the LS command result |
| $() |
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| # |
In Linux, # is commented as long as the # begins with an invalid comment |
| $ |
The value used to invoke the variable, if the value of the variable name is to be called, needs to use the definition of the $name variable Name=user1 |
| \ |
A transfer character precedes a special meaning symbol and loses its special meaning \ $name is not a variable |
Variables: Linux has 1, user-defined variables, 2, environment variables, 3, positional parameter variables, 4, predefined variables user-defined variables: variable definition: [[email protected]] #name =user1 [[email protected]] #ha ha=$ (DATE) variable overlay: [[email protected]] #name = "$name" 222 [[email protected]] #echo $name user1222 or using name=$ {name}222 View variables as above: We can use set to view variables (all variables in Set view system include custom variables) [[Email protected]]# set | grep namename=user1222 unload Variable unset name Environment variables: Setting environment variables: Export variable name = variable value you can use the Pstree command to view the process structure PS1 to modify the delimiter [[Email protected]]# settings Pre-defined variables:
| Pre-defined variables |
Role |
| $? |
The return status of the last command executed, if the value of this variable is 0, indicates that the previous command was executed correctly; If the returned value is not 0 proof that no successful execution, the specific return value can be Baidu query return error code |
| $$ |
Process number (PID) of the current process |
| $! |
Process number (PID) of the last process running in the background |
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Receive keyboard input: read [options] [variable name] option:-P "prompt message": Output prompt when waiting for read input-t number of seconds: the Read command waits for user input and executes the default-n character number after the number of seconds after the-t option is used: REA The D command accepts only the specified number of characters and executes-S: The data entered by Silver City, suitable for confidential information such as passwords BASH operator: Declare declaring variable type [[email protected]] #declare [+/-][options] Variable name option:-: Set type attribute to variable +: Type attribute of the Cancel variable-i: Declare the variable as an integer Type-x: Declare a variable as an environment variable (or export variable)-P: shows an example of a declared type that makes a variable: [[email protected]] #aa = 11; bb=22; Declare-i cc= $aa + $bb && Echo $cc 33 The most common way is cc=$ (($aa + $bb)) in the operation we just use the external $ (()) Double parenthesis Inside the algorithm is the same as the mathematical formula algorithm for example: [email Protected]] #aa =$ (((11+3) *3/2) && Echo $aa 21 until the result is 21 and logic with && logic or | | Variable substitution method This table is similar to the ternary operator in PHP: for example: [Email protected]]# Environment variables: (environment variable allowed) environment variables are generally uppercase environment variable profile: 1.source command: [[email protected]] #source configuration file or. The configuration file allows him to take effect immediately invalid restart/ETC/PROFILE/ETC/PROFILE.D/*.SH/ETC/BASHRC the environment variable profile for the above three paths is valid for all users ~/.bash_profile ~/.BASHRC profile environment variables for the current user when the environment profile for the above two paths is in effect Flowchart: Logoff Environment Profile: ~/.bash_logout default is empty history command profile: ~/.bash_history Shell Login Information: Post-logon information: Valid for both local and remote:/ETC/MOTD default is empty can add [[email protected]] #echo "AAA" >>/etc/motd[[email protected] "#exit [email Protected]] #从新登录后就有了本地终端登录信息:/etc/issue Remote terminal logon information:
Shell Learning Path: Shell Basics Daquan 1
