Linux learning -03-permissions for files and directories-2

Linux file extension: A Linux file can be executed, and his first column of the 10 attributes, and the file name is not at all related.

Common extensions:

*.sh: script or batch file (scripts), because the batch file is written using the shell, so the extension is compiled. Sh

*z, *.tar, *.tar.gz, *.zip, *.tgz: Packaged compressed files. This is because the compression software is gunzip, tar and so on, due to different compression software, and take its associated extension

*.html, *.php: Web-related files, respectively, representing HTML syntax and PHP syntax of the Web file!. html files can be opened directly using the Web browser, as for. php files, you can use the client side of the browser to find the server side, to get the operation The results of the Web page!

Linux directory configuration 650) this.width=650; "Src=" http://s3.51cto.com/wyfs02/M00/5D/B5/wKioL1UjmOnDauF_AAqX7hNyKK0481.jpg " title= "illustration. png" alt= "wkiol1ujmondauf_aaqx7hnykk0481.jpg"/>

650) this.width=650; "src=" http://s3.51cto.com/wyfs02/M01/5D/B9/wKiom1Ujl73gYZuMAAqX7hNyKK0746.jpg "title=" plot. png "alt=" Wkiom1ujl73gyzumaaqx7hnykk0746.jpg "/>

/(Root, root): Related to the boot system; The following cannot be separated from the root directory.

#/etc: Configuration file

#/bin: Important Execution file

#/dev: Required Device profile

#/lib: function library required to execute the file does not require the core module

#/sbin: Important System Execution files

/usr (Unix software Resource): Related to Software installation/execution;

/var (variable): related to the system operation process.

Absolute path vs. relative path

Absolute path: The name of a file or directory, such as/HOME/DMTSAI/.BASHRC, that is started by the root directory (/).

Relative path: The file name of the relative two current path is spelled. For example./home/dmtsai or. /.. /home/dmtsai/and so on. Anyway, the beginning is not/is the relative path of the wording, the relative path is "Your current path relative position" to represent the

The observation of CentOS

Uname-r

2.6.18-128.el5 <== can see the actual core version

Lsb_release-a

LSB version, distribution version

Linux learning -03-permissions for files and directories-2