linux shell

From the programmer's point of view, the shell itself is a program written in C language, from the user's point of view, the shell is the user and the Linux operating system communication Bridge. The user can either enter command execution or use shell scripting to do more complicated operations. In the increasingly pe

First, topsy variables and environment variables Variables are an essential part of any programming language and are used to hold variables of various types. Scripting languages are mostly weakly typed languages (dynamic languages), which means that when you use a variable, you don't have to declare the type of the variable in advance, just assign the value directly. In bash, the value of each variable is a string. The value is stored as a string, regardless of whether you use quotation marks w

A simple ShellProgram Let's look at a shell program. ----------------- #! /Bin/sh # this is to show what a example looks like. echo "our first example" Echo # This inserts an empty line in outputecho "we are currently in the following directory. "/bin/pwdechoecho" this directory contains the following files "/bin/ls Shell Structure: #! /Bin/shThe following script is interpreted and executed using

With Crontab you can execute a shell script or a series of Linux commands at a specified time. For example, the system administrator schedules a backup task to run every dayHow do I add a job to cron?# crontab–e0 5 * * */root/bin/backup.shThis will run at 5 o '/root/bin/backup.sh every morning.Description of Cron ItemsThe following is the format of the crontab file:{minute} {Hour} {Day-of-month} {Month} {Da

The bash shell supports only one-dimensional arrays, but there are no restrictions on the number of arguments.Declare an array:Declare-a Array(In fact, you don't have to declare that you can assign a value directly to a variable in an array, and bash knows that it's an array)Array Assignment:(1) array= (var1 var2 var3 ... varn)(2) array= ([0]=VAR1 [1]=var2] [2]=var3 ... [N]=varn)(3) Array[0]=var1Arrya[1]=var2...Array[n]=varnTo calculate the number of

proprietary unices. Like bash and dash, It is backward-compatibleWith the Bourne shell but adds new features and syntax. ksh introduced cursor-key navigation ofShell history, as well as providing arrays and floating-point math. For a long time, KSh was proprietaryUNIX Software of att, so pdksh (now mksh, http://mirbsd.de/mksh) is a free software equivalentTo ksh93. after ksh93 was released under IBM's common public license in 2005, most GNU/

Http://www.cnblogs.com/suyang/archive/2008/05/18/1201990.htmlFrom the programmer's point of view, the shell itself is a program written in C language, from the user's point of view, the shell is the user and the Linux operating system communication Bridge. The user can either enter command execution or use shell script

From the programmer's perspective, shell itself is a program written in C language. From the user's perspective, shell is a bridge between the user and the Linux operating system. You can enter commands for execution and use shell script programming to perform more complex operations. With the increasingly sophisticate

The shell of a Linux system is not just a command, but an interpreter of other commands. You can debug other commands to complete the compilation. So how should shell commands be used in Linux systems? In fact, as a command language, the interactive interpretation and execution of user input commands is on

ShellYesuser andLinuxThe interface between operating systems. There are multiple shells in Linux, where Bash is used by default. This chapter describes how shell works, shell types, General shell operations, and Bash features. What is shell? As the operating system

=$ (date"+%y:%m:%d%h:%m:%s") AIpavacount=0; -Ipunreachcount=0; - the #Init Log File -Echo$CurT>>IpCheckerDetailLog.txt -Echo$CurT>>PCheckerResLog.txt - + echo Starting ping ... - #Read Ip + whileRead IP A Do at ifPing-c 1-w 1$ip>/dev/null; Then -Echo$ipis avaliable -Echo$ipis avaliable >>IpCheckerResLog.txt -ipavacount=$ (($IpAvaCount+1)) - ElseEcho$ipis unreachable -Echo$ipIs unreachable >>IpCheckerResLog.txt inipunreachcount=$ ((1 +$IpUnReachCount)) - fi to Done + - #Statistics t

I. Description of the Catalogue1.1 Bin General user, executable system built-in commands1.2 Sbin system administrator, executable system built-in commands1.3 Boot boot file directory, start the relevant files are saved in this1.4 Dev Device Management files, such as mobile hard drives, USB drives, optical drives, etc.1.5 Home User home directory, in general: A user will have a corresponding folder, named after the user name1.6 lib dynamic link library shared library, type. dll file library for W

This article introduces the shell commands in linux from five aspects, including Shell variables, basic structure of Shell, return value of Shell functions, detailed description of Shell functions, and special variables in

Read the CU forum Shell 13 After a few small experiments, prepare to forget!Shell 13 Q Address: http://bbs.chinaunix.net/thread-218853-1-1.html#!/bin/bashfunction func_com () {Local a=1 local b= "2c3" Echo ${a}b echo $ab}function Func_arra Y () {echo "##### func_array #####" local path= "/home/stone" source $PATH/include/tt.ini #echo $name Local srand= (1 3 5 2) Local srand_num=${#srand [*]} for ((i=0;iLinu

What is a shell?Shell is the command interpreter, is the UNIX operating system user interface, the program from the user interface to get input information, the shell of the user program and its input translated into the operating system kernel (kernel) can recognize the instructions, and the operating system kernel finishes executing the output returned by the

Tags: cut exit Express Concise tutorial Call Shell variable experience syntax table Series article starter platform for Jelly want personal blog. Jelly think, is an original technical article sharing site. Here jelly will share his technical experience, technical gains and losses, technical life. I want to wait for you in jelly, and I hope you can share with me your technical loss and expectations. The Magic of LinuxI'm not going to tell

specific environment variables to define the system environment.These variables are already set up on the Linux system.6.5 Setting the PATH environment variablePATH: Defines the directory used for command and program lookups.The Echo $PATH directory is separated by colons.You can add a new search directory to an existing PATH environment variable. Like what:GCC Hello.c-o xcyGenerally only./xcy RunBut after adding the environment variable, you can run

Shell The shell also has a way of executing commands called batching (Batch), in which the user writes a shell script, which has many commands that allow the shell to execute the commands one at a time without having to hit the command one by one. Shell scripts and programm

Examples of common Linux commands and Bash Shell scripts, bashshellSummary The Linux Command isText-based input/outputAccording to the simple functions, loose input, and rigorous output of the program mentioned in the Unix philosophy, various program combinations can have more powerful functions, the main reason for this flexibility is that

Related Links: linux (1) Events (2) http://www.bkjia.com/ OS /201205/131408.html?linuxlinux( 3) Events (4) ---- user management details (5) ---- common user management commands (6) ---- process management details http://www.bkjia.com/ OS /201205/132474.html?linuxthat thing (7) ---- File System Management http://www. B Kjia.com/ OS /201205/133789.html a simple shell program. Let's look at a