Shell

The variables in the shell are stored as strings, even if you assign values to the value of the shape unless you declare the variable by declare-i. In the case of numerical/arithmetic operations, you may find the following $ x=121$ echo $x

When you install new software in a terminal environment, you can often see the Information dialog box pop up and need your input. The type of dialog box has a password box, checklist, menu, and so on. They can guide you in an intuitive way to enter

The variable is a string, and we assign a value. The assigned value can be a number, text, file name, device, or any other type of data. A variable is a pointer that does not exceed the actual data. Shell, you can create, assign, and delete

In Linux shell programming, in most cases, test commands can be used to test conditions, and here's a simple introduction,For example, comparing strings, judging whether the file exists and whether it is readable, etc., usually uses "[]" to

Shell Features--Linux has a variety of shells to use, the default for Bash,bash has the following key features.1. Command Memory AbilityPress the up and down keys on the command line to find a pre/Post input command. These commands are recorded in ～/

Special symbols and their escapeAs you know, a shell command is made up of a command name and its arguments, for example cat testfile , where cat is the command name and Testfile is a parameter. The shell passes the parameter testfile to the cat

Environment is Centos7/bin/bashNote When you copy a test, be sure to change the IP segment in the example to its own IP network segment.CTRL + Z You can enter the script into the background and see the process kill.1.#!/bin/bashFor i in {1..254} #定义1

ITerm2 is an OS X next open source free terminal tool, as a substitute for terminal, compared to it has its own features, such as screen cutting, System hotkey, check copy and so on (below is a brief introduction). The use of zsh, paired with ITerm2,

Shell script Programmingcompiler-------Interpreter static language: compiled language, strongly typed (variable), converted into executable format beforehand. c/c++/java/c# Dynamic Language: Interpreted language, weak type. The side explanation

the shell can often be seen: >/dev/null 2>&1 Eg:sudo kill-9 ' ps-elf |grep-v grep|grep $1|awk ' {print $4} ' 1>/dev/null 2>/dev/nullThe result of the command can be defined in the form of a%> output/dev/null represents an empty device fileWhere

For example, comparing strings, judging whether the file exists and whether it is readable, etc., usually uses "[]" to represent the condition test.Note: The space here is important. The space to ensure the square brackets. I have wasted a lot of

SSH is a toolkit to replace Telnet, FTP, and R commands, mainly to solve the problem of password transmission on the Internet. For system security and user's own rights, it is necessary to promote SSH. SSH is the abbreviated form of the English

has always been to execve what exactly do, always make confused, originally look at the design of the Linux kernel art, this part of the explanation is very not meticulous, this combination of Dr. Zhao's book, re-understand this part of the

ObjectiveThe topic said a bit long, in fact, is the following several things, the first is that the shell command can be executed within the program, and then pass the execution results to the variable, so that the subsequent transaction processing,

0.echo Command entry: (Default bash support, CSH not supported)-N does not output line breaks-E Open backslash ESC escape-e Suppress backslash ESC escape (default)Both 1.echo and printf can print output information, except that Echo adds a newline

Originally always use the Tp-link router itself with the peanut shell Dynamic DNS plus Router port mapping function, can be directly accessed from the external network to the intranet computer port.Later found that the peanut shells provided by the

  Note: When performing some performance tests, we sometimes want to calculateProgramSometimes, you may write a shell script to control the performance test (for example, you want to run n times to obtain the average value). In short, one of these

The shell is a special program used as an interface between the user and the heart of the operating system, a program called the kernel, the kernel is loaded into memory at boot time, and manages the system until shutdown. it creates and controls

I. Preface Shell programming is widely used in the Unix/Linux World. Mastering shell programming is also the only way to become an excellent Unix/Linux developer and system administrator. The main task of script debugging is to find the cause of the

1. Redirection 1. Standard input (stdin): code 0, use 2. standard output (stdout): the code is 1, use> or>;3. Standard Error output (stderr): Code 2, Use 2> or 2>; Eg: Yee @ LOONG :~ $ Ifconfig> 1.txtYee @ LOONG :~ $ Vim 1.txtYee @ LOONG :~ $ LS-Al 2