How to Recursively Change file Permissions in Linux

In Linux, file permissions are an important aspect of system security. These permissions control who can read, write or execute a file or directory. Sometimes, you may need to change permissions recursively, meaning to apply the same permission changes to all files and subdirectories within a directory.

In this article, we will discuss how to recursively change file permissions in Linux using the “chmod” command.

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Syntax of chmod command

The syntax for chmod command is as follows:

Here are some commonly used options with chmod:

• -R: Recursively changes permissions on all files and directories within the specified directory.
• -v: Outputs a message for each file processed.
• -c: Outputs a message only for files that have changed.

Changing permissions recursively using chmod

To recursively change file permissions in Linux, follow these steps:

1. Open a terminal window and navigate to the directory you want to change permissions for.
2. Use the following command to change permissions recursively for all files and subdirectories within the directory:
   chmod -R [permissions] [directory]

   1	chmod -R [permissions] [directory]

3. For example, if you want to give read, write and execute permissions to the owner and read and execute permissions to group and others for all files and directories within the “/var/www/html” directory, use the following command:

   chmod -R 755 /var/www/html 
   

   Here, the 7 gives read, write and execute permissions to the owner, 5 gives read and execute permissions to the group and others, and -R makes these permission changes recursive.

4. Use the ls -l command to verify that the permissions have been applied recursively:

   ls -l /var/www/html 
   

   This will list all files and directories within the “/var/www/html” directory along with their permissions.

Changing permissions recursively using symbolic mode

You can also use the symbolic mode with the chmod command to change file permissions recursively. This method allows you to change permissions in a more granular way. Here’s how to use the symbolic mode:

1. Open a terminal window and navigate to the directory you want to change permissions for.
2. Use the following command to change permissions recursively for all files and subdirectories within the directory:
   chmod -R [who][operator][permissions] [directory]

   1	chmod -R [who][operator][permissions] [directory]

   Here, who specifies who you want to apply the permission changes to, operator specifies what operation you want to perform on the permissions, and permissions specifies the new permissions you want to set.

3. For example, if you want to give read, write and execute permissions to the owner, read and execute permissions to the group, and execute permission to others for all files and directories within the “/var/www/html” directory, use the following command:

   chmod -R u=rwx,g=rx,o=x /var/www/html 
   

   Here, u represents the owner, g represents the group, and o represents others. The = operator sets the permissions to the exact values specified, and the “rwx” stands for read, write, and execute permissions.

Conclusion

Recursively changing file permissions in Linux is a simple process using the chmod command. You can use either the numeric or symbolic mode to apply permission changes recursively to all files and directories within a specified directory. However, be careful when changing permissions recursively, as it can have unintended consequences and potentially cause security issues if not done properly.