Linux

6-7-8 chapter about spin lock synchronization in the proposed The use of spin locks in operations in the lower half of the interrupt processing is especially necessary: the lower half process and the process context share data, because the

File permissions are divided into: read, write, executable Each file is divided into three kinds of users: the main user, the same group of users, other system users expressed in 10 digits: drwxr-xr-x First represents file type-represents normal

Maximum Effective permissions Mask Mask refers to specifying the maximum valid permissions, and if root gives the user ACL permission, is required and mask permission "phase" To get the user's real rights. Setfacl-m m:rx filename Permissions to

Memory and Swap Graphics According to the picture collation trend contrast number Mem Change Trends change trend of swap 1 Flat Rise 2 Rise Drop 3 Rise Flat

This two days played the next Development Board, installed an Android system, 2.3.3 System. But the installation of software can only be installed into the file system, the so-called internal space, but the board of the file systems only 120M,

File Testgrep content: 1. Show all rows that contain sans 2. Show all names starting with J in the line 3. Show all rows ending with 700 4. Show all rows that do not include 834 5. Show all birthdays in December line 6. Show all such

Due to a power outage or power failure, you need to see Linux boot time/restart time, common commands: 1, who command to viewWho-b View the last time the system started.Who-r View the current system run time. 2. Last reboot view Linux system

If you want to find "hello,world!" in the current directory String, you can do this: Grep-rn "hello,world!" *: Indicates all files in the current directory, or it can be a filename -R is recursive lookup -N is the line number displayed -R Find

about the Idle process Which is the pid=0 process. It is the first process created after the kernel completes initialization, and executes when the system is idle. Its code is simple: for (;;) pause (); Emphasize that the idle process is a

1. Commonly used /: Root directory./: Current directory.. /: Up-level catalogsCDS: Toggle Current DirectoryLS: displaying current directory contentsPWD: Display the entire directory namemkdir: Creating foldersTouch: Create a fileIfconfig: View

After Linux is installed in the virtual machine under XP system, the Linux interface in virtual machine VMware is too small, becauseThe Linux resolution is too low (usually 800x600) and can be changed by installing VMware ToolsResolution to 1024x768

Tools for viewing target and binary files 1.readelf– target file with "Gcc-a a.c"-> a.o 2.objdump– View target file && binaries "objdump-h a.0" process address space 1.task_struck structure that stores information about the process 2. Runtime

What is a thread Linux thread is a special kind of process, with its own task_struct, the kernel does not have special scheduling algorithm and data structure to characterize the thread, but only as a common process, but only with other processes

The first embedded Linux development environment construction 1.1.2 Embedded Development SCM (Single Chip microcomputer) microcontroller, MCU (Micro Controller unit) microcontroller, SoC (System on a Chip): Systems-level chip, on one chip due to

Identify ports------------- Gpio uses an integer ID between 0~max_int and cannot use negative numbers. Use the following function to check the legality of a port number: int gpio_is_valid (int number); using GpioThe first step-------------using IO

My blog Address What happens when there is not enough memory, the result is very simple, Linux memory used up, unable to request a buffer, the kernel will pick the process to kill it, in general, killing the application of memory program. Frequent

Configuration is simple, Java deployment Getting started configuration, As follows: 1, Decompression installation package [Root@localhost software] Tar zxvf jdk-8u152-linux-x64.tar.gz 2. Edit System Environment variables [Root@localhost

Top Display Linux processes top-07:57:26 up min, 4 users, load average:0.06, 0.05, 0.06 tasks:234 Total, 1 running, 233 sleeping, 0 stopped, 0 zombie %cpu0:1.0 us, 0.3 sy, 0.0 ni, 98.7 ID, 0.0 wa, 0.0 hi, 0.0 si, 0.0th %cpu1:0.7 us, 1.3 sy, 0.0 ni, 9

Vi/etc/rc.d/rc.localAdd:/usr/local/httpd/bin/apachectl Start2:[registered as service]Cp/usr/local/httpd/bin/apachectl/etc/rc.d/init.d/httpdVI httpdFind: #!/bin/shAnother line, increase:# chkconfig:35 70 30The first of the three numbers added in the

Backup Log Xiaoming is a server administrator, he needs to back up the forum data every day (here we use log substitution), back up the day's log and delete the previous log. And the file name is the year-month-day format after the backup.