Shell

The reason to write this article, is because the Internet a lot of articles about the reprint, crontab command of the grammar is wrong, are directly turned, although very simple, but also will waste time Ah, especially for the first time to write

Article Source: http://www.dataguru.cn/thread-331456-1-1.html Today you want to make an error in the Yarn-client state of Spark-shell:[Python] View plaincopy [Hadoop@localhost spark-1.0.1-bin-hadoop2]$ Bin/spark-shell--master yarn-client   Spark

Logical judgment in the shell Format 1:if condition; Then statement; FI//If the condition is met, then execute the statement[[email protected] shell]# cat if1.sh #!/bin/basha=5if [ $a -gt 3 ]then echo okfi[[email protected] shell]# sh -x if1.sh +

Sometimes installed Yum package, found that some have been installed, but if the installation, Yum needs to check the source, output a bunch of information, look very annoying, and then think of the first check after installation, if the Local has

echo Display in shell script with color display, echo display with color, need to use parameter-EThe format is as follows:Echo-e "\033[word background color; text color m string \033[0m"Example: Echo-e "\033[41;36m something here \033[0m"Where 41 of

Original linkTerminal (terminal, or physical terminal):is a device, not a program, typically a device that provides a command-line user interface, typically a screen and keyboard, or some other physical terminal.Virtual Terminal:Screen and keyboard

Summarize:(1) printf uses reference text or space-delimited parameters, which can be used to format strings in printf, as well as the width of strings, left and right alignment, and so on. Default printf does not automatically add line breaks like

Linux shell String Operations (length, find, replace) detailedString-related operations are often involved in the shell batch process. There are a lot of command statements, such as: awk,sed can do string various operations. In fact, the shell built

1. expr computes the integer variable valueS= ' Expr 2 + 3 'The arithmetic symbol and the parameter must have the space separate;2. Let command let s= (2+3) echo $s 3, for statement For variable in list

1.login & Non-login ShellLinux system bootstrap, the kernel will create the INIT process for a series of system initialization operations. When each user logs in to the shell, the relevant login profile is read regardless of whether it is logged on

IntroducedUnderstand The boot sequence of Linux also helps to understand this content, loading the user environment is the last step of Linux boot. Different shells use different configuration files :　Bash (. Profile), Ksh (. Profiles), CSH (. Login)

Linux Run LevelLinux starts running at one level, and these run levels are listed below:0 System Stop1 Single user system, no login required2 Multi-user system but NFS not supported, command-line mode login3 full multi-user mode, command-line mode

Joined the caravan for some time, see the group inside the big head to check the blog, only to realize that I have not written homework. As the saying goes, the time is to kill the Pig knife!!! Cough, actually want to say, horse brother Video is

[[Email protected]:/etc]# tree/etc/ansible//etc/ansible/├──ansible.cfg├──hosts├──python.yml└──roles└──python_install├──files│└──python-3.6.6. tgz├──tasks│├──copy.yml│├──Install. Yml│└──main.yml└──templates└──python_install.SHDescription: Files:

2,WC [-LWM] Options and parameters: -L: only list rows; -W: How many words are listed(English word); -M: The number of characters; 3,Md5sum Md5sum [Option]... [file]... Print or check MD5. (128-bit) checksums. With no file, or whenFile

Problem: Switching a user through the su command does not enter the user's shell environment. Why? To solve this problem, we must be clear about the difference between using Login Shell and non-login shell. Login Shell:Complete logon process is

People who work with shell are familiar with shell programming in Unix/Linux. # is mentioned in all shell programming books #! /Bin/bash. What exactly does it contain? What does this string mean for the operating system? You may say, isn't it true

IntroductionYou can do many things without knowing how they actually work. For example, you don't have to understand the physical principle of engine combustion before you can start a car. Lack of electronic knowledge will not stopYou use a CD

Today, I wrote a shell script, which runs normally on my machine. To my colleagues, run the syntax error near unexpected token error. I can check the shell script on the left and right, but there is no way to search by Google, I found that a senior

Summary: three methods of executing shell scripts, fork, source and exec, are summarized.  Prerequisites 1. any program we run is a child process generated by the parent process. After the child process is completed, it is returned to the parent