Shell

1. If you judge some special usageIf [-Z $a] This indicates what happens when the value of variable A is emptyif [!-e file]; Then what happens when the file doesn't exist?if (($a ,==,!=,>=,$ $ does not exist, so n is empty;[Email protected] ~]# n= '

If you manage a large number of sites and servers, it is quite painful to modify the configuration file every time. So I thought of using shell scripts to generate bulk configuration files and configuration data. The following script is a shell

1, the variable with = assigned value when the left cannot have spaces. For example , UserName =nihao returns userName: Command not found . Because this place username as a command to deal with. The right approach is to Username=nihao.Careful is the

A related knowledge 1) By default, the standard input is the keyboard, but it can also come from a file or pipe (pipe |). 2) By default, the standard output is terminal (terminal), but can also be redirected to a file, pipe, or post quotation mark

Single-branch If condition statementIf [conditional judgment]; ThenProgramFiExample: Judging partition usage#!/bin/bash# Author:huangrui (email:[email protected]) rate=$(DF-H |grep "sda1"|awk '{print $}'|Cut-F1-D"%") if[$rate-GT the]; Then Echo

1. When defining variables, You cannot leave spaces on either side of the = sign.egGender=femal------------RightGender =femal-----------Wronggender= femal-----------Wrong2. Conditional test statement [the symbol is left blank on both sides .]egif

Shell Script (ii)#find查找文件 to find based on time, name, UID, GID, permissions, size, etc.A file or directory accessed within #-amin-10:10 minutes; a file or directory accessed +10:10 minutes ago. The time unit is minutes.#查找10分钟之前30分钟之内访问过的文件或目录Find/

Test file cat >testjasonjasonjasonfffffPress CTR + D to save1, Sort-usort -u testfffffjason2, UniqUniq TestjasonfffffjasonThis shows that Uniq needs to be sorted before it can be re-3, sort, pipe and uniq combined use Remove duplicates

$# 是传给脚本的参数个数$0是脚本本身的名字$1 是传递给该shell脚本的第一个参数$2是传递给该shell脚本的第二个参数[email protected] 是传给脚本的所有参数的列表$* 是以一个单字符串显示所有向脚本传递的参数，与位置变量不同，参数可超过9个$$ 是脚本运行的当前进程ID号$? 是显示最后命令的退出状态，0表示没有错误，其他表示有错误 Difference:@* Same point: All parameters are

The basic job of the shell is to execute commands.The shell executes each command you type.$CD work;ls-l whizprog.cFirst: The format is simple, separating the various components of the command line with a blank Space key or TAB key.Second, the

the Nginx service program written by Shell can be added to the/etc/init.d/directory first. chkconfig--add nginxd chkconfig nginxd on Service Nginxd Start Service Nginxd Stop service Nginxd "Restart | Reload | Test | Status " #!/bin/bash#chkconfig:-

Today learn bird's private dishes, according to the book hit a few shell script, but the total errorThe first is to use [] to determine the condition, = = does not work properlyThe second is to declare variables in the script to use declare, always

ls command file, directory Operation commandLS Displays the current directory by defaultLs-a Show All Files hidden filesLs-l Display file propertiesLS-LH Display File sizeLs-lt display files sorted by modified time cd Command Change

Setting environment variables#Set java_home=/root/deploy_ws/jre1.8.0#PATH = "$PATH:/home/user/bin"Calculate the length of a string#var = "12345"#echo ${#var}Shell currently in use#echo $SHELLQuerying the role of the current user#echo $UID//If root

A Brief History of Unix UNIX was originally developed by the Computer Science Research Center of Bell Telephone Laborataries, the first version of which was born in 1970 – shortly after Bell Labs withdrew from the Multics project. Among the

Http://c.biancheng.net/cpp/view/6998.htmlOpen a text editor, create a new file, the extension sh (sh for Shell), the extension does not affect the execution of the script, see the name is good, if you write a shell script in PHP, the extension is

grepIf you want to use a regular expression, add the parameter Grep-e "[a-z]+" #使用正则表达式or egrep "[a-z]+"-a-b output matches a few lines before or after the line-C to display a few lines at the same time-e matches multiple styles, such as GREP-E "cat"

Chapter II Shell ProgrammingThe following sections are described in this chapter:What is a shell?Basic ideasSubtle syntax: variables, conditional judgments, and program controlCommand ListFunctionExecution of commands and commandsHere

How shell scripts run$sh script.sh$sh/home/path/script.sh$chmod a+x script.sh; $./script.shEcho's three ways to use echo Hello World Cannot contain some special keywords, such as semicolons;echo "Hello word" Cannot contain some special characters,

Shell basics 3: shell Basics Cut is a selection command: It is to analyze a piece of data and retrieve what we want. In general, the selection information is usually analyzed for "rows", not the entire information analysis. (1) The syntax format is: