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In the shell, see ">1" and ">2" always do not understand what meaning. After the search on the internet to dispel doubts. Actually, this is two kinds of output. In a shell program, the most commonly used FD (file descriptor) is about three, respectively: 0 is a file descriptor that represents the standard input (stdin)1 is a file descriptor representing the sta

Tags: description command gadget should--standard standard output dev fileThis article was reprinted from: 11595985By default, there are always three files open, standard input (keyboard input), standard output (output to screen), standard error (also output to screen), and their respective file descriptors are 0,1,2. So let's take a look at the differences between the following redirection methods:>/dev/null 2>1In fact, it should be equivalent to thi

On the shell:0 indicates standard input1 indicates standard output2 indicates standard error output> default to standard output redirect, same as 1>2>1 means redirecting the standard error output to the standard output.>file means to redirect both the standard output and the standard error output to fileTo speak with an example:

[APUE exercise 3.5]./A. out> Outfile 2> 1 and./a. out 2> 1> Differences Between outfile　　Int main (){Printf ("output to stdio \ n ");Fprintf (stderr, "output to stderr \ n ");Return 1;}The result is as follows:　　Qun @ ThinkPad ~ /Tmp $./a. out> outfile

Problem description: there are now n ordered arrays in M groups, such as {1, 2, 3, 4}, {2, 3, 6}, {1, 3, 5, 7 }, select the data smaller than K in these arrays and return this value. Idea: Compare the minimum data selected each time by referring to the process of merging two Arrays

By default, there are always three files open, standard input (keyboard input), standard output (output to screen), standard error (also output to screen), and their respective file descriptors are 0,1,2. So let's take a look at the differences between the following redirection methods:>/dev/null 2>1In fact, it should be equivalent to this: 1>/dev/null 2>/dev/nul

2-1 Linux operating system and common commands, 2-1 Linux Edit it based on the beginner videos 2-1 and 2-2 of Marco's linux

Float floating "1" clear: both clear floating; "2" set parent element overflow: hidden to clear floating, "1" and "2" Floating float Figure 1 First clear floating: add an empty element and set its css style to clear: both; Figure

QML ranges from 1 to 2, and qml ranges from 1 to 2. As the project goes deeper, it needs to be transplanted to Android. The problem is that QML Android is compatible! Fortunately, the PC-side program is similar to the cell phone screen width ratio. Although the unit pixels and sizes are different, you can use proportio

What is a file descriptor. A file descriptor is a simple positive integer that identifies each file and socket that is opened by the process. The first three file descriptors (0,1,2) correspond to standard input (stdin), standard output (stdout), and standard error (STDERR) respectively. difference between "2>1 > File" and "> File 2>

Description defines a recursive function sumint sum (int n); function declaration, return 12+22+32+......+n2 and note: Sum is the value of the recursive function input positive integer n output12+22+32+......+n2 and sample Input5sample Output55/* Copyright (c) 2014, Yantai University School of Computer * All rights reserved. * File name: Test.cpp * Chen Dani * Completion Date: June 1, 2015 * version number: v1.0 * * #include Experience: This is a s

Would you like to send a value from PHP page 1 to 2, and then to pass 2 results back to the 1 show how to implement? Title I found the web based on HTML $_get[], this method must have a submit value, and return after the display is null Then read the net with JSON value, the result is half said JSON has double quotatio

Today in Ubuntu Kylin installed VirtualBox, and then I want to delete a new point, the result of normal situation can not be deleted, I will find the VirtualBox directory all deleted,And then through the Apt-get Remove and other commands can not be deleted, the title shows the errorChild process installed Pre-removal script returned error number 1On the internet to find a lap, a great deal of effort to find the following solutions, record,Http://www.xuebuyuan.com/2153374.htmlsudo gedit/var/lib/d

/* * Design 4 Threads 2 pairs of j-1 2 pairs of j+1 * * * * */ Class J { private int j = 0; public synchronized void Plus () {//j+ j + +; System.out.println ("+ +" + thread.currentthread (). GetName () + ":" + j); } public synchronized void minus () {//j- j--; System.out.println ("--" + Thread.CurrentThread (). G

[Go to] complete ArcGIS custom tool tutorial 1/2 I. Client -- Tag on the page:ClientAction = "EsriMapRectangle"ServerAction = "com. esri. adf. web. faces. event. ZoomInToolAction"ClientPostBack = "true"/>Ii. Client-clientActionClientAction refers to a javascript class, which must inherit EsriMapToolItem and overload several functions:Appendix 11. The first is: Object. inheritsFrom (Object parent), which is

In the shell program, the most commonly used FD (file descriptor) is about three, respectively:0 is a file descriptor that represents the standard input (stdin)1 is a file descriptor that represents the standard output (stdout)2 is a file descriptor that represents a standard error (STDERR)In the standard case, these FD are associated with the following devices, respectively:stdin (0): Keyboard keyboard inp

#!/usr/bin/env python# Coding:utf-8Import Redef Dealwith (Express): Express.replace ('+-','-') Express.replace ('--','+') returnexpressdef Col_suanshu (exp):if '/' inchexp:a,b= Exp.split ('/') returnStrfloat(a)/float(b))if '*' inchexp:a,b= Exp.split ('*') returnStrfloat(a) *float(b) def get_no_barcate (Express): Express=express.strip ('()') Print ('>>>', Express) whileTrue:ret= Re.search ("-?\d+\.? \d*[*/]-?\d+\.? \d*", Express)ifRet:res=Col_suanshu (Ret.group ()) Express= Ex

Transferred from: http://www.360doc.com/content/13/0523/16/7044580_287544243.shtml on the shell:0 indicates standard input1 indicates standard output2 indicates standard error output> default to standard output redirect, same as 1>2>1 means redirecting the standard error output to the standard output.>file means to redirect both the standard output a

Int a [5] = {1, 2, 3, 4, 5}; printf ("% d \ n", * (int *) ( a + 1)-2 );, printf % d What is the result of a certain convincing pen question in a certain year? The answer is 4. Why? My understanding (do not know if it is correct ): A is an array pointer of the int type [5], so a plus

Programming for computing1 ^ 1 + 2 ^ 2 + 3 ^ 3 + ...... + N ^ nWhere N is an arbitrary integer. (Note: consider the case where the result may be out of the long range) Note: This method usesInteger array elementsStores each digit of a large number. ====================================== # Include Using namespace STD; Const int n = 10000; // defines the maximu