A computer's performance:

1. Scale
Cluster: strength in numbers
. A load balancing cluster
. B high-availability cluster
. C High Performance Cluster (application layer) --- the Hadoop Cluster Map of reduces [+ the HDFS =
2. longitudinal extension application migration

{Linux system, everything is a file}

Second, the system starts:

---- power supply.
---- 2.BIOS chip (procedures)
[First Working: POST, the hardware device to check whether it is normal.
Second Working: System startup (boot 1. Select (a the reading order problems where location system (BIOS):. drive network (PXE) U disk CD / VDC ...) - 2 file system will need a hard disk, loaded into memory, the CPU to read and run; MBR partition: is to find and boot the system load, in other words, help to find the system files (BootLoader: size of 446 bytes)
LILO: embedded load, grub: boot-start program)]
---- 3. "we will this kernel is loaded, however, and can not run common applications" loading kernel
---- 4 At this point we want to run first application (init) --- [init:. the operating system divided into 0-67 levels; each level will run a corresponding application (specify the default start level) - read the default level 3 (command line)]

is important to remember several levels:
0-- shutdown level
1 - single-user mode level
3-- command line level
5-- graphical interface level
6-- restart

---- 5.rc .local // read the file system starts last, the administrator may need to boot commands, and add in here.
---- 6 Desktop.
Learn command to minimize the interaction with the computer
* chkconfig effect: when the specified service level on which the boot, startup or shutdown

-h --help 查看帮助
>>>--list

*例：>>>--level 345 Name <on/off>

* update -rc.d certain control program in Ubuntu boot;
-f force Force
[chkconfig can On Ubuntu, the need to install]

The basic format of three .linux command

command [options] [parameters]
[]: On behalf of the brackets, optional; specify a particular function to achieve command
<>: object code command executed; if not add <> objects must be added the representative can not be omitted.
Long integer options (not consolidated)
short integer options (can be combined)
extension (to know): command subcommand [options] Parameters *

IV. Hard and Soft Links

The basic Linux system commands
Summarized: Many hard link

V. the basic use of commonly used Linux commands

First, we continue yesterday's content, be extended

Question: If the command is not in the path path, how to solve?

1. This command can be run by an absolute path; (= absolute path of execution is the command itself, and some named, is the system default alias (add your own) -alisa;)
Which of the Command Find command // absolute path
or \ ls backslash run;

2. Add this path to the path to the PATH;
PATH = $ PATH: / XXX / XXX

3.LS --- // File Information Display
details -l // ll view files (attributes)
-i // InCode (attributes)
-H // Human human readable ()
-F behind the display file mark ( used to distinguish the file type)
-R & lt reverse display file contents

4.PWD ----- // display the current directory where the (path)

CD ---- // switch to the target directory
~ represents the current user's home directory (/ root / Home)
. Represents the current directory (with files beginning for hidden files)
.. the parent directory of the current directory
- After a deposit on $ OLDPWD directory

6.CD - // switch to a directory entry

7.touch --- // modification timestamp

例：>>>[[CC]YY]MMDDhhmm[.ss]
20 19 0 8 0 16 36. 22

-a modify the access time
-m modification time
-t modified to specify what time
-c modify the file Mtime, if the file does not exist, create a file
------ SATA
..atime (access time)
Mtime (time to modify the file contents)
ctime (modify file attributes)
Mkdir // Create a folder
-p create multilevel subdirectories recursively
-v displays detailed process of creating
tree / display all the root directory
[tree: a tree form, display the directory and file structure]
-L 1 NUM see how many sub-directory (see subdirectory)
-d display only files directory
8. rm ---- // delete
-f force forcibly remove (not delete the folder)
-i asked to delete the file, the default command (Alisa RM = 'RM -i')
\ RM abc
/ bin / RM abc
-r forced to delete directory (folder)
Extended about:
1. The default does not apply in the case rm rmdir to delete directories ---
rmdir only removes empty directories;
2. We will need to delete a file or directory under / tmp directory can be; / tmp directory for temporary files directory, 30 days have not been accessed files will be automatically deleted

VI. Respective owners owning group

The basic Linux system commands

Remember:
1. File system must be installed in the storage device
2. The file format operation in the installation system
common file system format in 3.Windows: (. 1) .NTFS (2) .FAT32
4.echo the PATH $ (environment variable) variable : some are named kernel
[Note: Capitalize variable]