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File and Directory access authority

For files and directories on Linux, "access authority" is set. You can manage restrictions such as allowing an account to read, allowing members of a group to write, not showing it to other accounts.

These access privileges are called "permission". This section explains how to check permissions of files and directories.

Last Update : February 28, 2019

File and Directory access authority Contents

  1. Display file/directory detailed information
  2. Check the owner/group of the file/directory
  3. How to read permissions

1. Display file/directory detailed information

You can check the owner, owning group, permissions etc of the file/directory by attaching "-l" (lower case L) to the ls command.

$ ls -l
total 28
drwxrwxr-x 2 test_user group1 4096  6月 28 08:42 dir1
drwxrwxr-x 2 test_user group1 4096  6月 28 08:50 dir2
-rw-rw-r-- 1 test_user group1    0  6月 28 08:42 file1.txt
-rw-rw-r-- 1 test_user group1    0  6月 28 08:42 file2.txt
lrwxrwxrwx 1 test_user group1   13  6月 28 08:51 test.txt -> dir2/test.txt

2. Check the owner/group of the file/directory

The owner of the file directory is displayed in the third column of the output of "ls -l".
The group of file directories is displayed in the fourth column of the output of "ls -l".

$ ls -l
total 28
drwxrwxr-x 2 test_user group1 4096  6月 28 08:42 dir1

in this case,
owner = test_user
group = group1
It means.

Notes

If you create a file or directory, the account you created will be the owner of the file and the primary group of the created account will be the owning group.

3. How to read permissions

You can check the permissions of the file/directory from the first 10 characters (eg "drwxrwxr-x") of the display output by ls - l. Each character has a meaning.

As for the part of "drwxrwxr-x", consider it into four as shown below.

How to read permissions

The first letter represents "file type". Indicates whether this is a file, directory, symbolic link, etc. The first character represents "file type". It indicates whether this is a file, a directory, or a symbolic link.

The next three characters (red underlined part) represent the permissions for the owner of the file.

The next three characters (green underlined part) represent the permissions for the owning group of the file.

The next three characters (blue underlined part) represent the permissions for others.

The meanings of r, w, x, and - are as follows.

symbol Corresponding authority
r file can be read
w file can be written to
x file can be executed (if it is a program)
- specific permission has not been assigned

Notes

There are s, S, t, and T in addition. I will explain it in another section.

There are various file types, but representative points are as follows.

symbol file types
- a regular file (rather than directory or link)
d a directory
l (lowercase L) a symbolic link to another program or file elsewhere on the system
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