Shell

Shell Execution Script 650) this.width=650; "Width=" 799 "height=" 321 "title=" QQ picture 20160809205710.png "Style=" width:607px;height:229px;float : none; "alt=" Wkiom1ep0pkiz2v4aac1d9tdasu417.png "src=" http://s4.51cto.com/wyfs02/M02

Command substitutionIn bash, $( ) and ` ` (anti-quote) are used for command substitution.command substitution is similar to variable substitution, which is used to reorganize the command line, complete the command line in quotation marks, and then

There are a number of ways to intercept strings in the shell, ${expression} There are 9 ways to use them. ${parameter:-word}${parameter:=word}${parameter:?word}${parameter:+word} The above 4 alternatives can be used for default values. ${#parameter}

There are usually 3 ways to perform mathematical operations in the shell:Expr commandFor example, expr 1 + 6 will return 7, the disadvantage of using expr is to encounter multiplication, or parentheses (because they have other meanings in the shell),

1. #号截取, remove the left character and leave the right character.     Code: Echo ${var#*//}where Var is the variable name, #是运算符, *//indicates that the first//and all characters on the left are deleted from the left.    Example:650) this.width=650; "

Resolve Bash Shell pin this newspaper error ': not a valid identifierWhen you edit the script in the shell, the runtime appears "': not a valid identifier", or it will appear (: Command not found, many inexplicable symbols) is likely you to edit

In shell scripts, all of our variables are stored as strings. So it becomes very important for the interception of strings.In a shell script, if you want to specify a string for interception, there are several ways to do it:The following examples

The difference between the anti-quote and $ ():Let's first look at an example:Create a file named Test.sh, enter the following two instructions in the file650) this.width=650; "Src=" Http://s4.51cto.com/wyfs02/M00/82/DB/wKioL1ditWDAq5FZAAAJ9atF8Qc539

Regular expressions Symbol p> meaning . Matches any single character in any ASCII, or letter, or number ^ Match beginning $ Match line end

Thank you for the 36,000 sectionCommon Shell Categories: BASH: is the GNU Bourne Again Shell, which is the default shell on the GNU operating system C Shell: The BSD version of Sun's shell Look at where the shell is on the

#break和continue命令: During a loop, sometimes you need to force the loop to break out when the loop end condition is not reached#break: Allow all loops to jump out (end all loops after execution)1 while: #死循环写法 #2 Do3 Echo-N"Input A number

#printf命令, format the output statement#用于格式化输出, is the echo-enhanced version, a limited variant of the C-Language printf library function, with slightly different syntax#是由POSIX标准所定义, the transplant is better than echo.#printf不会像echo自动换行, so add \ n

Http://man.linuxde.net/testHttp://blog.chinaunix.net/uid-24780853-id-2578709.html[email protected] ~]# man testtest (1) User Commands Test (1) NAME test - Check file types and compare Valuessynopsis Test EXPRESSION t EST [EXPRESSION] []

Original link: http://desheng666.blog.163.com/blog/static/4908408220121643953425/The expr command is generally used for integer values, but can also be used for strings. The General format is:Expr argument operator argumentExpr is also a manual

Usage of the Linux Cut commandFont: [Increase decrease] Type: Reprint time: 2013-10-03 I want to commentCut is a selection command that analyzes a piece of data and takes out what we want. In general, the selection of information is usually for

When a user logs on to a Linux system, the login shell executes the required script in the following order.First, execute/etc/profile this startup script, in/etc/profile This startup scripts will call all the startup scripts in the/ETC/PROFILE.D

In the Linux shell programming, the process control structure and the statement, also is the shell script the emphasis, does not understand the friend, follows the script small compilation together to study.Linux control flow structure learning.One,

The main purpose of the HDFs design is to store massive amounts of data, meaning that it can store a large number of files (terabytes of files can be stored). HDFs divides these files and stores them on different Datanode, and HDFs provides two

Print variables[Email protected] shell]# echo $PATH/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/binCustom variables[[email protected] shell]# a=1 custom variable [[email protected] shell]# echo $a print variable 1Write a script

Configuration Management Remote ScriptingVim/srv/salt/shelltest.slsShell_test:Cmd.script: #模块和函数-Source:salt://test/1.sh #脚本源路径-User:root #客户端执行者身份, can be other usersvim/srv/salt/test/1.sh#!/bin/bashTouch/tmp/111.txtif [-d/tmp/1233]Thenrm-rf/tmp/123