First, the system start
1、
Power (BIOS chip --- 1, power on self test to check the hardware is normal)
desktop
Starting System
Reading order problem where the position of the system (BIOS): HDD Network (pxEu disc CD / DVD)
The system will need to file hard disk, loaded into memory, allowing the CPU to read and run the MBR partition (BootLoader): boot the system is used to find and load: Lilo, grub (the first stage, 1.5 stage, the second stage) .
2, the operating system is divided into 0-67 levels, each level runs to a corresponding application; (specify the default start level). This, I have to complete the kernel is loaded, however, and can not run common applications; this time, we have to run the first application -init:
The default start level
1 0 off single-user mode (secure mode) 3 5-line command to restart the graphical interface 6
Two, Linux basic format of the command:
<1> command [options] Parameters
<2> chkconfig [] (optional) brackets denote the dispensable; develop specific functions to achieve the commanded
<3> <>: command execution object represents an object, if not added <> can not be omitted representatives
<4> sub-command has command [options] Parameters
Third, the commonly used Linux using command of
1, the command can be run by an absolute path;
Absolute path is executing the command itself, while others command is the default alias (add your own) -alias; which command // Find command absolute path
2, adds this path to the path to the PATH
PATH=$PATH:/XXX/XXX
| pwd displays the current path |
| $ Pwd there is a default environment variable; to understand; |
| - the current user's home directory (/ root / home) |
| The current directory (with files beginning for hidden files) |
| . . The parent directory of the current directory |
| - $ OLDPED stored on a directory through |
| cd to the target directory |
| touch modification timestamp |
| -a modify the access time |
| -m Modifications Modifications time t |
| -t modified to specify what time |
| stat atime access time |
| mkdir create a folder |
| -p create multilevel subdirectories recursively |
| -v detailed display creation process |
| tree to tree form, display the directory and file structure |
| -L NUM see how many level subdirectories |
| -d display only the catalog file |
| rm // delete files |
| -f force forced to delete |
| -i asked to delete the file, the default command (alias rm = 'rm-i') |
| -r delete a directory file |
| rm delete |
| clear 清屏 Ctrl+I |
| -F behind the display file mark |
Fourth, expand :
1, does not apply default rm delete the directory --rmdir only delete empty directories
2, we will need to delete the file or directory under / tmp directory can; tmp as a temporary directory, files not accessed for 30 days will be automatically deleted
3. If you have to delete some files, we matched up by find, and then delete the row;
4, computer performance: scale longitudinal extension
5, the cluster: big data clusters include:
High availability cluster load balancing cluster High Performance Cluster (application layer)
Hadoop cluster = mapredues + HDFS (storage)
