Shell

Functional Requirements:A shell script, in order to use a multi-process, to start more than 10 background running programs, in order to prevent the script than the background process prematurely end caused unpredictable impact, now to determine

In the shell, you can run the script in 3 ways:1. ./script_name or source./script_name2 Direct./script_name3./script_name &Join script Script_name There are two command command1,command2, then, when run in the first way, Command1 and Command2 both

Type [-AFTPP] name [name,...]-A prints all possible cases of name, such as Type-a ls, which will print LS is aliased to ' ls--color=auto ' and LS is/bin/ls-F does not go to find function-T Print alias,keyword,function,built-in,file these 5 types-P

I took over two projects, suddenly the eldest brother asked me what configuration of the server, then I was ignorant, has not been too concerned about this thing, just to ensure that the server normal operation, the site can access normal, the other

In the shell, a command is written in 3:1 can write directly (Normal Command)2 can be placed in double quotation marks ("Command")3 can be placed in single quotes (' Comand ')In this 3, the execution flow of the command is not the same, as shown

Sort commandSort is output in ascending order of ASCII code, and is compared sequentially from the first characterCommon options-C test file is already sorted-R Reverse Sort-N Sort by numeric numeric size-t Specifies the separator-K Specify Domain-U

In the load-spark-env.sh script below the spark bin , there are the following statements: If [-F "${user_conf_dir}/spark-env.sh"]; Then # Promote all variable declarations to environment (exported) variables set-a . "${user_conf_dir}/spark-

The shell condition test can be done in two ways:Test parameters Testing Content[Parameter test content]First, test file type:TEST-E file name (test file exists)[-e FileName] Test file exists, note the space on both sides of the bracketTest-f file

The call file system (FS) shell command should use the form $HADOOP _home/bin/hadoop FS.All FS shell commands use the URI path as the parameter.The URI format is Scheme://authority/path.The scheme for Hdfs,hdfs is HDFs, such as Hdfs://localhost:9000/

Learning basic Linux Commands Command Description $ ls This command was used to check the contents ofThe directory. $ pwd This command was used to check the presentWorking directory.

One, the main use of the Bash Shell in Linux; View the supported shell types available on Linux systems :Vim/etc/shellThe way to perform shel footsteps:1. Give footsteps the ability to execute permissions and invoke the script using a relative or

Business requirements: the need to migrate 1000多万个 files from one directory to a remote machineIdea: Use wget to move the file one after another, because the number of files is relatively large, if a bit in the loop operation, it will be very slow.

#!/bin/sh ()  {        if [ -f $1 ];then                 case $1 in                    *.TAR.BZ2)       tar xjf $1       ;;                          *.tar.gz)        tar xzf $1       ;;                    *.BZ2)           bunzip2  $1      ;;         

First, grep ----"Line filter Tool" grep (Global search Regular expression (RE) and print out of the line, fully search regular expressions and Printing a line is a powerful text-search tool that can use regular expressions to search for text,

Ask for 1-100 and A. Non-recursive1 #!/bin/bash 2 sum=0 3 str= "" 4 for I in {1..100} 5 does 6 let sum+=i 7 str+= "$i +" 8 done 9 echo ${str%+}= $sumOutput Result:650) this.width=650; "src="

One. grepgrep (Globally search a Regular Expression and Print) is a powerful text search tool , it can use regular expressions to search for text, print matching rows, but does not affect the contents of the original file , and by the return value

Assigning values to variables#定义变量, note that there is no space on either side of the equal sign variable=#定义环境变量Export variable=#双引号: Can contain spaces, can escape special characters variable="" #$ () or anti-quote: assigns a command

1. Remove the left character and leave the right character1). Use # InterceptExample: str= "http://www.baidu.com"650) this.width=650; "Src=" Http://s1.51cto.com/wyfs02/M01/82/DC/wKioL1djQu_CLXeEAAAzIuXnc10469.png-wh_500x0-wm_3

650) this.width=650; "src=" Http://s2.51cto.com/wyfs02/M01/82/E0/wKioL1djmxjx5LUrAACG8N3z-pA754.png "style=" float: none; "title=" 0.png "alt=" Wkiol1djmxjx5luraacg8n3z-pa754.png "/>The maximum, minimum, and average values of a set of numbers are

4-7 shellsort.c1#include 2#include"4-1 createdata.c" //function to generate random numbers3 #defineArraylen 10//number of data elements that need to be sorted4 voidShellsort (intA[],intN//Hill Sort5 {6 intd,i,j,x;7d=n/2;8