printf usage

The Shell implements a simple calculator function with the following script:[[email protected] scripts]# Cat Jisuan.sh#!/bin/bashprint_usage () {printf $ "usage:$0 NUM1 {+|-|*|/} num2\n" Exit 1} #判断传入的参数是不是3个if [$#-ne 3] then print_usagefifirstnum=$1

Implementation code#include #include#include#include#include//perror ()#include //exit ()#defineBuffer_size 1024intMainintargcChar*argv[]) { intfrom_fd; intto_fd; unsignedintFile_len; intRET =1; CharBuf[buffer_size]; Char*ptr; if(ARGC! =3)

simply write a small program to understand the mechanism of some signalsAlthough the combination of blocking and non-blocking operations and the Select method is sufficient for querying the device for most of the timeEnough, some situations cannot

Network communication programming is to write through the computer and other programs to communicate between the program, the program of mutual communication can be called the client program, the other party is called the Service program, the

One, what is the Linux driver exactly what is a thing:1, actually the Linux drive and the common Linux API does not have the essential difference, only uses the Linux drive Way and uses the Linux API the way is different;2. The Linux system maps

Ignore the SIGCHLD signal and give it to the kernel to process the subprocess, avoiding the zombie process.Server-side:1#include 2#include inch.h>3#include 4#include 5#include 6 7 #defineMAXLINE 40968 9 intMainintargcChar**argv) {Ten One signal

Linux Opendir and Readdir won't update along with directory changingtable of Contents 1. Result 2. Temporary Fix method 3. Test 1ResultAccording to my experiment, opendir () would just record a static state of opened directory.

1 Download OpenCV source codeOpenCV Source: http://opencv.org/2 Installing the required packagesCMake build-essential Libgtk2.0-dev3 Decompression Source 4 configuration OpenCVEnter the root of the source code execution:cmake.You can also use

getopts CommandUseProcesses command-line arguments and verifies valid options.Grammargetopts option string name [parameters ...]DescribeGetopts is designed to run in a loop, and each time a loop is executed, getopts checks the next command-line

Domain name and IP information parsing/etc/hosts file has some IP address and domain name hostname information/ETC/RESOLV.CONF has the IP address of the DNS serverstruct hostent{ char *h_name; // official name of the host Char **h_aliases; /

The next section continues,1. Reading input from the keyboard#!/bin/bashread-p ' Please input something: ' Inputecho ' your input: ' $inputOperating effect:./read1.shplease Input Something:123your input:1232. While Loop and Case

/******************************************************************* * Linux Read input device demo * Description: * This article is mainly to understand the previous colleague wrote input device a demo program. * 2016-3-24 Shenzhen Nanshan Ping

#include #include #include #include #include #include int main (int argc, char *argv[]){struct sockaddr_in sin = {0};struct Arpreq myarp = {{0}};int sockfd;unsigned char *ptr;if (argc!=2) {printf ("Usage:%s \n", argv[0]);Exit (0);}sin.sin_family =

1 //server-side server.c2#include 3#include 4#include string.h>5#include 6#include 7#include 8#include inch.h>9 #defineMAXLINE 4096Ten One //socket (int domain, int type, int protocol) A //protocol Domain socket type Specify protocol -

#include #include #include Function: Keep only Chinese, English, numerals and spaces, will.!?; Replace with line breakChar *repunlawchar (char *instr, char *outstr) {#define Split_char ' \ n 'if (instr = = NULL) {Instr[0] = ' + ';outstr =

#include #include#defineProcessbasicinformation 0typedefstruct{USHORT Length; USHORT MaximumLength; Pwstr Buffer;} Unicode_string,*Punicode_string;typedefstruct{ULONG allocationsize; ULONG ActualSize; ULONG Flags; ULONG Unknown1;

In the Bowen (1) and (2), respectively, in 4 ways to write a prime filter algorithm, respectively, is JavaScript in Browser, node. js, Ruby and C; The end result is C fastest, node. js Second, JS in B Although not slow, but extremely unstable, So

Just look at the jar and make a short note here because you need to run a jar program that collects data on the server at a timed time:1.eclipse-export to generate a runnable jar to the specified directory. The third-party jar package that you rely

Process CommunicationProcess is the smallest unit of system allocation resources, the different processes are isolated from each other, Linux is often used for process communication in several ways Anonymous pipelines and well-known

1 for complex Linux drivers and libraries such as HAL, it is necessary to debug them using a variety of methods. Examples include setting breakpoints, stepping through code, outputting debugging information, and so on. 2 Print kernel debug