Rhcsa note 2

[[email protected] ~]# man ls

 man The structure of the help information of the command is as follows ：

 man Several sections of the manual

section 1： User instructions , View help for command

section 2： system call , See help for functions that can be called by the kernel

section 3： Library calls , Check out help for functions and Libraries

section 4： equipment , See help for special files （ Mainly /dev A file in a directory ）

section 5： File format , Check out the help for the configuration file

section 6： game , Check out the help for the game

section 7： miscellaneous , Conventions and agreements, etc , for example Linux file system 、 Network protocol 、ASCII code And so on

section 8： System instructions , Check the help of the commands available to the system administrator

section 9： Instructions inside the kernel , Check the help of kernel related files

(4)info page

info And man It's almost the same use , Are used to query the command usage or file format . But with the man page Different yes ,info page It is to split the file data into paragraphs , Each paragraph is written on its own page , And in each page , There are also similar web pages 『 Hyperlinks 』 To jump to different pages , Each individual page is also called a node (node). However, the description file of the target data you want to query must be info Only when it is written in the format of info Special features of ( Like hyperlinks ). And this support info By default, the file of the command is placed in /usr/share/info/ In this directory

3.date command

Used to display or set the time and date of the system

Grammar format ： date [OPTION]... [+FORMAT]

Example ： according to “ year - month - Japan Hours : minute : second The day of the year Week , What quarter The time zone What day of the week ” View the current system time in the format of

 4.timedatectl command

Used to set the time of the system

English full name ：time date control

Grammar format ： timedatectl [OPTIONS...] COMMAND ...

timedatectl Parameters and functions in the command ：

  Check the system time and time zone ：

 5. ls (list) View the files in the directory

 6.file command

Used to detect the type of a given file

Grammar format ：file [ -bchikLnNprsvz ] [ -f namefile ] [ -F separator ] [ -m magicfiles ] [file or folder] ...
                  file -C [ -m magicfile ]

7.stat command

Used to display the status information of the file .stat The output information of the command is more than ls The output of the command should be more detailed

Grammar format ：stat [OPTION]… FILE…

stat The information that can be viewed by the command includes ：

File： Show filename
Size： Show file size
Blocks： The total number of data blocks used by the file
IO Block：IO Block size
regular file： file type （ General documents ）
Device： Equipment serial number
Inode：Inode Number
Links： Link number
Access： File permissions
Gid、Uid： Ownership of documents Gid and Uid
access time： This is our last visit （ It's just a visit , No changes ） Time of file
modify time： It means when we last modified the file
change time： Indicates the last time we changed the file properties , Including authority , size , Properties and so on
Birth time : File creation time ,crtime, However, it is found that this property linux obsolete , The current status display results are -

  Parameter description ：