time wait linux

basically at the same time, resulting in 5 SIGCHLD signals are delivered to the server parent process almost simultaneously. As shown below:That is, almost at the same time, 5 SIGCHLD signals are delivered to the parent process, which in turn will cause the zombie process to appear. Because UNIX generally does not queue the signal, which resulted in 5 SIGCHLD submitted, only one sig_chld function, the rema

Wait (waits for the child process to break or end)Header file #include Use of Waitpid and wait in Linux "Go"

Linux Shell sleep/wait (reprinted) 2007-04-27 18:12Bash's basic configuration is made up of configuration files./etc/profile is called a global configuration file for the shell.Another file in the personal directory under the personal directory/.bash-profileThere's a file in the personal directory./ETC/BASHRC is the second global profile, which holds (function aliases, etc.) also has a configuration file in

In Linux drivers, it is best not to use continuous loops to do the work of waiting for some kind of event, but to use another method, sleep and wake.Waiting for the queue to work is the process of sleep and wakeThe basic principle of the sleep and wake process, when the driver waits for an event to enter hibernation, wakes up the driver code of the hibernation state when the event occurs. Use:Static Declare_wait_queue_head (BUTTON_WAITQ); Defining th

Linux system monitoring, diagnostic tools Tophttp://my.oschina.net/leejun2005/blog/157910Linux system Monitoring, diagnostic tool IO waithttp://my.oschina.net/leejun2005/blog/355915Introduction to the Lsof usage of Linux system monitoring and diagnostic toolshttp://my.oschina.net/leejun2005/blog/153584Analysis and solution of high CPU load problemhttp://yikebocai.com/2014/11/cpu-load-too-high/

Zombie does not take up memory and does not occupy the CPU, on the surface we can not care about their existence, however, in fact, the UNIX system limits the maximum number of processes that can exist at one time at a time. If the program does not clean up the zombie in time, it will end up with too many processes, and there will be an error when the new process

#include Makefileobj-m+= test.orootfs =/rootfskernel_src=/lib/modules/' uname-r '/buildall:make-c $ (kernel_src) M= ' pwd ' Modulesclean: Make-c $ (kernel_src) m= ' pwd ' cleanrm-rf appinstall:make-c $ (kernel_src) m= ' pwd ' Modules_install install_mod_path=$ (ROO TFS) APP:ARM-LINUX-GCC App.c-o appIoctl.c#ifndef__IOCTL_H__ # define __ioctl_h__#include Linux device driver-

) assumes that the child process normally ends with a value other than 0.Wexitstatus (status) Gets the end code returned by the child process exit (), usually preceded by theWifexited to infer whether the ability to end gracefully uses this macro.Wifsignaled (status) assumes that this macro value is true when the child process is terminated by a signalWtermsig (status) Gets the signal code that the child process has aborted because of the signal, and usually uses wifsignaled to infer it before u

Original URL: http://www.2cto.com/os/201203/124851.htmlWait (waits for the child process to break or end)Header file #include "Go" Linux waitpid and wait usage

int status;pid_t t = fork (), if (t) {waitpid (T, status, 0);}else{System ("VI temp.txt"); Exit (0);} After both the parent and child processes have finished executing the parsing process: if and else or select branch.The main reason is that thefork () function is called once and returned two times . The difference of two returns is that the return value of the child process is 0, and the parent process returns the process ID of the new child process. When returned, the parent process executes w

)Background execution: ""Users sometimes take a long time to execute commands, which can affect other things. The best way to do this is to put it in the background. Programs running in the background can continue to execute after the user logs off. When you want to place the command in the background, add "" after the command.Linux Shell | |When the shell executes a command, it returns a return value that is saved in the shell variable $? In When $?

Recently found that most of the production server used in the work, through the Securecrt/xshell/putty terminal software to SSH connection, waiting for the prompt to enter the password for a long time, always need more than 5 seconds, after observation found that the original is Sshd_ The cause of configuration in config;Vim Open/etc/ssh/sshd_config1. Find "Gssapiauthentication yes" to modify it to "Gssapiauthentication no"2. Find "Usedns yes" to modi