Linux

This article was reproduced from: http://blog.csdn.net/dosculler/article/details/7932315First, jiffies timer, hz=100, precision can only reach 10ms.Note: Use Jiffies+msecs_to_jiffies (xx ms), can achieve MS level, but not enough precision#include

with the rapid development of today's information Age, With its many advantages, Linux stands out from the operating system and is favored by more and more computer users. Linux is a set of security, stability, freedom and many other advantages in

Linux system is a multi-user multi-tasking time-sharing system, any user who wants to use system resources must first request an account from the system administrator and then enter the system as this account.On the one hand, the user's account can

1, the Linux command can be divided into internal commands and external commands:The built-in commands are memory-resident when the system is started, so the execution efficiency is high.The external command is the software function of the system,

A file Operation command　　1) Create an empty file or modify the file timeTouch file nameCommand name: TouchCommand path:/bin/touchExecute Permissions: All Users2) DeleteRM-RF file name-R Delete Directory-F MandatoryCommand name: RMCommand English

1. PrefaceYesterday summed up the Linux under the network programming "surprise group" phenomenon, give the method of Nginx processing surprise group, using mutual exclusion lock. As an example of the advantages of multi-core, the current network

1. Introduction:A. Role:is to prevent the lack of access to the situation, the general permissions have the owner, the group, the other people of the three, when these three can not meet our needs to use ACL permissions 　　 B. Background of the story:

# total number of cores = number of physical CPUs x number of cores per physical CPU # Total Logical CPUs = number of physical CPUs x number of cores per physical CPU X number of hyper-threads # View the number of physical CPUs cat/proc/cpuinfo|

1. Framebuffer application Programming(1) Open the device file(2) Obtaining device informationMacro-defined commands in/linux/fb.hImmutable information Fscreeninfo, using the IOCTL parameter has a Fbioget_fscreeninfo macro name, indicating the use

Switch (args[0][0])//parse instruction to see what each instruction corresponds to {case ' d '://display switch (args[1][0] {case ' Q '://display queue show_mq (FD); Break Case ' d '://display

typedef struct MSG_HDR_S { uint32 msg_type; UInt32 Msg_len; UInt32 msg_src; UInt32 msg_dst; } msg_hdr_t; typedef struct MSG_S { msg_hdr_t Hdr; Uint8 data[100]; } msg_t;Here is an explanation of the message

Usage Description Service commands are used to manage system services such as Start, Stop (stop), restart (restart), view status, and so on.The related commands also include chkconfig, NTSYSV, etc., chkconfig to view, set the runlevel of the service,

Lock important files as follows:Chattr +i/etc/passwd/etc/shadow/etc/groupp/etc/gshadowUnlocking filesChattr-i/etc/passwd/etc/shadow/etc/groupp/etc/gshadow Note: The I representative here may not change this file arbitrarilyTo see if a file is

Cd:change DirectoryCD [/path/to/somedir]CD: Switch home directory ~: Switch back to your home directory ~USERNAME: Switch to the home directory of the specified user -: Toggles the related environment variable back and forth between the

User-managed 2 Important files:/etc/passwd and /etc/shadow. The/etc/passwd file contains the user's information, which does not contain a password:each line in the passwd file represents a user, and each line is divided into 7 fields using ":" as

introduction of Shared memoryShared memory is one of three IPC (inter-process communication) mechanisms. It allows two unrelated processes to access the same logical memory. Shared memory is a very efficient way to pass data between two processes

Today when reading the "large-scale Web services Development Technology" book, the book mentions the SAR command, it feels very useful, it is necessary to sort out the study. (For a Linux beginner, do not miss a learning opportunity: P)Opening your

1. Cat:concatnateOptions:-n:number Display Line numbers-e:end displays the identifier at the end of each line (the identifier at the end of each line in Linux is $, and $+ returns in Windows)-v:visible visible display of nonprinting characters2.

Network Team, Network Team Network Group team: Aggregates multiple network cards for fault tolerance and throughput improvement. 1. Create a network group Interface Nmcli connection add type team con-name TEAMname ifname INTname [config

Tcpdump and tcpdump Directory: 1.1 tcpdump options 1.2 tcpdump expression 1.3 tcpdump example Tcpdump uses the command line method to filter and capture interface data packets. Its rich features are manifested in flexible expressions. Tcpdump