LINUX Managing file/folder permissions and ownership

The Unix files access is controlled. There are three types of access (permissions):

  • read
  • write
  • execute
Each file belongs to a specific user and group (ownership).
Access to the files is controlled by user, group, and what is called other/everyone permission bits and is usually set using a numerical value.
For example, 644 as permission bit will result in:
Owner / User Group Other/ Everyone 644
Each number represents the access level and it can be from 0 to 7.

The access level, depending on the number is as follows:

  • 0 - no access to the file whatsoever
  • 1 - execute permissions only
  • 2 - write permissions only
  • 3 - write and execute permissions
  • 4 - read permissions only
  • 5 - read and execute permissions
  • 6 - read and write permissions
  • 7 - read, write and execute permissions (full permissions)

Thus the above 644 permissions example will look like this:

Owner / User - Read and Write Group - Read and Write Other/ Everyone - Read only
To allow a script to be executed and read by everyone but the only one who can write in it is your user, you would need to set 755 as permissions:
  • Owner / UserGroupOther/ Everyone
  • 7 - Full permissions
  • 5 - read and execute
  • 5 - read and execute
Changing the permissions to 700 will make the file visible only for your username and no one else and setting it to 444 will allow only the file creator to modify it.
The command you need to issue to actually change the permissions is called ‘chmod’ and it generally looks like this:
chmod 755 configuration.php
The above example changes the permissions of configuration.php file and sets them to 755.
You can recursively change the permissions of all folders and files using the recursive argument:
chmod -R 755 *This will modify the permissions of all files in the current folder and
set them to 755.
You might wonder what the above user/group values are. These two settings are the actual ownership flags for a file or a folder.
Each file has a primary user that owns it and a group assigned to it. To change those values, a special command exists -- ‘chown’.
Its syntax is very easy:
chown user: group file
For example:
Chown user:
siteground configuration.php
The above line will set the owner of the file to ‘user’ and the group to ‘siteground’.
Changing ownership recursively is also permitted and the flag (naturally) is -R: chown -R user: siteground *

Comments

Post a Comment

Popular posts from this blog

Java : Variables Declaring

[1]. Java Variables Variables are containers for storing data values. In Java, there are different types of variables, for example: String - stores text, such as "Hello". String values are surrounded by double quotes int - stores integers (whole numbers), without decimals, such as 123 or -123 float - stores floating point numbers, with decimals, such as 19.99 or -19.99 char - stores single characters, such as 'a' or 'B'. Char values are surrounded by single quotes boolean - stores values with two states: true or false [2]. Declaring (Creating) Variables To create a variable, you must specify the type and assign it a value: Syntax type variable = value ; Where type is one of Java's types (such as int or String), and variable is the name of the variable (such as x or name). The equal sign is used to assign values to the variable. To create a variable that should store text, look at the following example: Example Create a variable called  name  of type  Stri...
Read more

SQL Self JOIN

SQL Self JOIN A self JOIN is a regular join, but the table is joined with itself. Self JOIN Syntax SELECT column_name(s) FROM table1 T1, table1 T2 WHERE condition; T1 and T2 are different table aliases for the same table.
Read more