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This article mainly explains the "summary of basic file and directory management commands under Linux". The content of the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "the summary of basic file and directory management commands under Linux".

. Represents this layer directory

. . Represents the previous level of directory

-represents the previous working directory

~ represents the Chinese folder where "current user identity" is located

~ account represents the home folder of the user account (account is an account name)

Cd: switching directories

Cd ~ vurtne switch to the home folder of the user vurtne, namely / home/vurtne

Cd ~ means to return to your home folder, that is, / root. Equivalent to cd

Cd. . Switch to the upper directory

Cd-represents to go back to the directory just now

Pwd: displays the current directory

Pwd-P shows the actual working directory instead of the directory name of the linked file itself

(e.g. / var/mail)

Mkdir: create a new directory

The code is as follows:

Mkdir-m 770 test

Configure directory permissions directly

The code is as follows:

Mkdir-p test/test1/test2/test3/test4

Create a recursive directory

Rmdir: delete an empty directory

The code is as follows:

Rmdir-p test/test1/test2/test3/test4

Delete a recursive directory (empty directory)

Variable to execute file path: $PATH

PATH= "$PATH": / root adds / root to PATH

① users with different identities have different default PATH and different commands that can be executed at will (such as root and general users)

The ② PAHT can be modified, so the average user can still modify the PATH to execute something located in / sbin or

/ usr/sbin command to query

③ uses absolute or relative paths to directly specify the file name of a command to execute, which is more correct than querying PATH

The ④ command should be placed in the correct directory to make it easier to execute.

⑤ this directory (.) is best not to be put in PATH.

Cat: displays the contents of the file from the first line

Tac: display from the last line

Nl: output line number when displayed

More: display the contents of the file page by page

Less: similar to more, you can turn the page forward

Head: just look at the first few lines head-n 3 / etc/passwd

Tail: just look at the last few lines

Od: reading the contents of a file in binary mode

Ls-al-- full-time: check the full time format

Cp,rm,mv: copy, delete, move

Because cp has a variety of file attributes and permissions, you should pay attention to:

Does ① need to retain the information of the source file completely?

Whether the ② source file is a soft connection file

Whether the ③ source file is a special file

Whether the ④ source file is a directory

The code is as follows:

Basename / etc/sysconfig/network

Get the last file name

The code is as follows:

Dirname / etc/sysconfig/network

Get the directory name

Modify the file time or create a new file: touch

-a: only modify the access time

-c: only the time when the file was modified, if the file does not exist, no new file is created

-d: you can follow the date you want to modify instead of the current date, or you can use-- date= "date or time"

-m: modify only mtime

-t: you can follow the time you want to modify instead of the current time, in the format of [YYMMDDhhmm].

Mtime (medify time): the last time a file or directory was modified

Ctime (change time): the time when the file or directory was last changed (the original data is changed, that is, attributes)

Atime (access time): the last time a file or directory was accessed.

File default permissions: umask

Umask: specifies the "default value of permissions for the current user when creating a new file or directory".

By default:

If a user creates a "file", there is no executable (x) permission by default, that is, only r and w permissions, that is, a maximum of 666. The default permissions are as follows:

The code is as follows:

-rw-rw-rw-

If the user creates a new "directory", since x is related to whether you can enter this directory, all permissions are enabled by default, that is: drwxrwxrwx

Umask has a lot to do with the default permissions for new files and directories.

For example: suppose your umask is 003, what are the permissions of the newly created files and directories in the case of umask?

A: umask is 003, so the permission removed is-wx, so:

File: (- rw-rw-rw-)-(- wx) =-rw-rw-r--

Directory: (drwxrwxrwx)-(- wx) = drwxrwxr--

File hiding attributes: chattr, lsattr

Chattr (set the hidden properties of the file)

The code is as follows:

[vurtne@localhost ~] $chattr [+-=] [ASacdistu] file or directory name

Parameter: ()

+: add a special parameter, while other existing parameters remain unchanged

-: delete a special parameter, while other existing parameters remain unchanged

=: there are only parameters that follow.

Note: because the setting values of an and I are common in property settings, and many setting values must be set as root.

Therefore, only two items an and I are listed.

A: when an is set, this file can only add data, but cannot delete or modify data, only root

You can set this property.

I: it can make a file "cannot be deleted, renamed, and set links cannot write or add data." For system security

Holism is of considerable help. Only root can set this property.

Lsattr: show file hidden attributes

The code is as follows:

[vurtne@localhost ~] $lsattr [- adR] file or directory

Parameters:

-a: show the properties of the hidden file

-d: if you are following a directory, only the attributes of the directory itself are listed, not the file names in the directory

-R: even the data of the subdirectory is listed side by side.

File special permissions: SUID,SGID,SBIT

The meaning of the two permissions of s and t is related to the account number and program of the system.

SetUID

① SUID permissions are valid only for binary programs (binary program)

The ② operator needs to have runnable permissions for the program.

③ this permission is valid only while running the program (run-time)

The ④ operator will have the permissions of the program owner (owner).

SetGID

SGID has the following functions:

① SGID is useful for binary programs

The operator of the ② program needs to have the permission of x for the program

The ③ operator will get the support of the program group during the run!

When a directory is configured with SGID permissions, it will have the following functions:

If a ① user has r and x permissions to this directory, the user can enter this directory

The valid group (effective group) of ② users in this directory will become the group in this directory.

③ purpose: if the user has the permission of w in this directory (you can create a new file), the new file created by the user

The group of the new file is the same as the group of this directory.

Sticky Bit

Sticky Bit, SBIT is currently only valid for directories, but has no effect on files. Its effect on the directory is: ① when the user has w, x permissions to the directory, that is, write permission

② when a user creates a file or directory under this directory, only himself and root have the right to delete the file

View file type: file

You can use file to query the basic data of a file, such as whether it belongs to ASCII or data file, or binary, and whether it uses a dynamic function library (share library), and so on.

Query for commands and files:

Which (looking for "execution file")

-a: lists all commands that can be found in the PATH directory, and not just the name of the first command found.

Whereis (looking for specific files)

-b: only look for files in binary format

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

-s: only look for source source files

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

Locate

-I: ignore case differences

-r: can be followed by the display of regular expressions.

Find

The relationship between permissions and commands

1. What are the basic permissions to enable users to enter a directory to become a "working directory"?

Commands that can be used by ①: commands such as cd to change working directories

Permissions required for the ② directory: the user needs to have at least x permissions on this directory

③ if the user wants to use ls to look up the file name in this directory, the user also needs r permission to this directory.

2. What is the basic permission for a user to read a file in a directory?

Commands available to ①: cat, more, less, etc.

Permissions required for the ② directory: the user needs to have at least x permissions on this directory

Permissions required for ③ files: users need to have at least r permissions on the file!

3. What are the basic permissions to allow users to modify a file?

Commands available to ①: nano or vi/vim editor to be introduced in the future, etc.

Permissions required for the ② directory: the user must have at least x permissions in the directory where the file is located

Permissions required for ③ files: users must have at least r, w permissions to the file

4. What are the basic permissions to allow a user to create a file?

The permissions required by the directory: the user should have the permission of wMagnex in this directory, with emphasis on w permissions.

5. What are the basic permissions for users to enter a directory and run a command under that directory?

Permissions required for the ① directory: the user must have at least x permissions in this directory

Permissions required for ② files: users need to have at least x permissions in this file.

PS: modify the Chinese directory under home to English directory

Habit problem, like to use the "desktop", "document", "picture, public", "download" created by fedora for you in the home directory.

"Music", "Video" and other directories. After a long time, I always feel a little happy. When I operate the files in these directories under the command line, I always switch to input.

When you enter the law, it is not so sound and dripping. I wish I could change these Chinese catalogs into English ones. Some people will say that renaming is not enough.

I tried to rename it, but there seems to be something wrong with it. For example, rename "download" to "Downloads" and the browser's default download directory has changed.

When I look it up on the Internet, I know that some skilled people despise the IQ of desktop users and think that people who use desktops can't even manage their own files and directories.

Must help you take the initiative to do a good job. So freedesktop.org, who manages the Linux desktop, came up with a xdg-user-dirs to actively create a bunch of subdirectories for users.

It is convenient for us to use, so we have those directories under the home directory.

All right, let's get to the point, how to modify it, open the terminal, and enter the command under the terminal:

The code is as follows:

[vurtne@localhost~] $export LANG=en_US

[vurtne@localhost~] $xdg- user- dirs- gtk- update

At this time, a configuration interface will pop up to indicate whether to change the Chinese directory to the English directory. Check and no longer prompt, OK.

Chinese directories with no content will be deleted, while directories with content will be maintained. And create 8 corresponding English catalogs as follows:

"Desktop", "Download", "Templates", "Public", "Documents", "Music", "Pictures", "Videos".

At this point, the commonly used Chinese catalogue you see in "location" has become an English directory. You only need to copy the contents of the original Chinese directory to the corresponding English directory

And delete the Chinese directory.

Then execute it.

The code is as follows:

Export LANG=zh_CN.UTF-8

To display Chinese. OK, all right, three commands will do.

But it is also troublesome to remember three commands for one change. Can you forget it.

Then log out, and then select "English (united states)" in the login interface.

When you enter the system, you find that the whole system has become English.

At the same time, a dialog box will pop up to indicate whether to change the user directory and select "Update names".

Confirm and log out again, select "Chinese" in the login interface, and after entering the system, the system becomes Chinese again

The same dialog box will also pop up and select "Keep old names".

OK, it's done, and you don't need to remember a single command to get the results you want.

Thank you for your reading, the above is the "summary of basic file and directory management commands under Linux". After the study of this article, I believe you have a deeper understanding of the summary of basic file and directory management commands under Linux, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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