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This article shares with you the content of a sample analysis of file and directory management in linux. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

= basic command =

# pwd [- P]: displays the current working directory

-P: the option indicates that the actual working directory is displayed instead of the directory name of the connection file itself

# mkdir [- mp] directory name: create a new directory

-m: set the permissions of the file directly. You don't need to see the default permissions (umask)

-p: recursively create a directory

# rmdir [- p] directory name: delete empty directories

-p: delete along with the upper empty directory

# echo $PATH can display the executable file path. If you are in the current directory, you must enter. / xx to execute. The default is the current path. Not in PATH.

# ls [- adhlSt] directory: lists the files in the directory

-a: all files, including hidden files

-d: list only the information of the directory, not the files in it

-h: the uppercase of the file is displayed in KMagazine G

-l: display details one line at a time

-S: sort by file size, not by default file name

-t: sort by file modification time

-full-time: the full time when the file was modified

Copy of the file =

# cp [- apdriu] source1 source2... Directory

-a: equivalent to-pdr

-p: copied with the file properties instead of using the default attributes (commonly used for backup)

-d: if the source file is link file, copy the link file instead of the file itself

-r: recursive replication for directory replication behavior (commonly used)

-I: if the target file exists, ask about the operation when overwriting (commonly used)

-u: update the target file if the target file is older than the source file

Note: the difference between cp dir1/* dir2/ and cp-r dir1/ dir2/ is that the former copies all files under dir1 to dir2, and the latter copies dir1 directory to dir2 (files under-r associated directories are also recursively copied)

= deletion of files =

# rm [- fir] file or directory

-f:force, ignoring files that do not exist, without warning messages, and without asking the user whether to delete them

-I: interactive mode, which asks the user whether to delete

-r: recursive deletion, be careful!

= the movement of the file =

# mv [- fiu] source1 source2... Directory

-f:force, don't ask, just overwrite

-I: the target file already exists. Ask whether to overwrite it

-u: overwrite only if the target file already exists and the source is relatively new

= get path and filename====

# dirname / etc/sysconfig/network get / etc/sysconfig

# basename / etc/sysconfig/network to get network

= = query of file contents =

Cat: display from the first line

Tac: the last line begins to display

Nl: when displayed, output the line number

More: page by page, can only be turned backwards

Less: page by page. You can turn the page forward and backward. The man page is the less that is called.

Head-n 100: show only the first 100 lines, head-n-100: all the previous lines, excluding the last 100 lines

Tail-n 100-f / var/log: show only the last 100 lines (- f is useful for continuous display), tail-n + 100: show all subsequent lines, but not the first 100 lines

Od: reading the contents of a file in binary mode

= three more important time attributes of the file

Mtime:modification time, the time when the file was created or modified

Ctime: when the status of a file changes status, such as permissions or properties

Atime:access time, the time when the file was accessed and read

You can use the command: ls-l-time=atime/ctime/mtime display. Default is mtime

The above three times can be modified with the touch command, which can be used to create an empty file.

= default permissions and hidden permissions =

Chattr sets hidden properties, and lsattr views hidden properties

# umask-S: view default permissions

The default permissions for files and directories are not used:

For files:-rw-rw-rw

For directories: drwxrwxrwx

The value of umask refers to the part of permissions that are cut on this basis.

# umask 002 can be set

# chattr [+-=] [ai] file or directory

+: increase, if it originally exists, don't move,-it's the same, = assign a value directly

A: this file can only add data, cannot delete or modify data, only root can set this thing.

I: this is awesome, so that a file can not be deleted, renamed, set the connection can not be written or added data, only root can be set.

# lsattr [- adR] file or directory to view hidden attributes

= file special permissions: SUID,SGID,SBIT====

When s appears on the x of owner, it stands for SUID, which means:

* SUID permission is valid only for binary programs (binary program)

* the executor needs to have the executable permission of x for the program

* this permission is valid only during program execution (run-time)

* the executor will have the permission of the program owner.

When s appears on the x of group, it stands for SGID, which means:

In terms of files->

* SGID is useful for binary programs

* the executor of the program must have the permission of x for the program

* the executor will be supported by the user group of the program during execution.

For catalogs->

* if a user has r and x permissions on this directory, the user can enter the directory

* the valid user group (effective group) of the user under this directory becomes the group of the directory

* if the user has w permission in this directory, the group of the new file created by the user is the same as the group of this directory.

SBIT (Sticky Bit) is only valid for directories, and the purpose is:

* when the user has wmai x permission for this directory

* users create files or directories under this directory, which can only be deleted by themselves and root

4: SUID,2, SGID,1, SBIT

Chmod 4755 filename, you know. If S and T mean that they don't even have the permission for x, then the settings of s and t are useless, they are just equipment, empty.

Queries for commands and files

# which command: find the location of the command, according to $PATH.

Lookup of file name:

First use whereis and locate to find, fast, because directly query the database, but can not find it and then use find, directly search the hard disk

# whereis [- bmsu] file or directory name

-b: only look for binaries

-m: only find the files under the manual path of the description file

-s: only look for source source files

-u: find other special files that are not in the above three options

# locate [- ir] keyword

-I: ignore case

-r: regular search

The last find command, too powerful to write, check it yourself.

Find / var-mtime + 4: file name greater than or equal to 5 days ago

Find / var-mtime-4: filename within 4 days or less

Find / var-mtime 415 days that day

Find / home-user yidao

Find /-nouser

Find /-name password: a file named password

Find / var-type s:socket file

Find /-perm + 7000

Find /-perm + 7000-exec ls-l {}\

Find / etc-name'* httpd*': wildcard form is also fine

Thank you for reading! This is the end of this article on "sample analysis of file and directory management in linux". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, you can share it out for more people to see!

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