2-Day2-3-ImportanceOfDirectoryPermissions

Importance of Directory Permissions

1. Entering the Directory (cd):

   • The execute permission on a directory allows you to change your working directory using the cd command.

   • Without execute permission, you cannot navigate into that directory.

2. Accessing Files Inside the Directory:

   • Execute permission enables you to access files and subdirectories within the directory.

   • You need execute permission to list the contents of a directory using ls -l.

3. Example: Navigating and Accessing Files

   Let's create a directory named my_directory and explore its permissions:

   mkdir my_directory
   ls -ld my_directory

   Output (example):

   drwxr-xr-x 2 user group 4096 Mar 25 10:00 my_directory

   • The d indicates a directory.

   • my_directory is the directory name.

   • Permissions (drwxr-xr-x): Read, write, and execute permissions for the owner, read and execute permissions for the group and others.

4. Try navigating into the directory:

   cd my_directory

5. Access files and subdirectories inside my_directory.

What Happens Without Write Permission?

If you lack write permission for a directory:

• You cannot create new files inside it.

• You cannot modify existing files within the directory.

• For example, if you try to create a new file or rename an existing file, you'll encounter a "Permission denied" error.

1. Execute Permission for a Directory:

   • When you remove execute permission from a directory, you won't be able to access its contents or traverse into subdirectories.

   • Let's create a directory named "my_directory" and remove execute permission:

     mkdir my_directory
     chmod -x my_directory

   • Now try to list the contents of "my_directory" using ls. You'll get a "Permission denied" error.

2. Adding Execute Permission Back:

   • Let's add execute permission back to the directory:

     chmod +x my_directory

   • Now you should be able to list the contents of "my_directory" again.

3. Write Permission for a Directory:

   • When you remove write permission from a directory, you won't be able to create, rename, or delete files within it.

   • Let's create a new file inside "my_directory":

     touch my_directory/my_file.txt

   • You'll get a "Permission denied" error because we removed write permission.

4. Adding Write Permission Back:

   • Let's add write permission back to the directory:

     chmod +w my_directory

   • Now you should be able to create files within "my_directory".

5. Read Permission for a Directory:

   • When you remove read permission from a directory, you won't be able to list its contents.

   • Let's try to list the contents of "my_directory" again:

     ls my_directory

   • You'll get a "Permission denied" error.

6. Adding Read Permission Back:

   • Let's add read permission back to the directory:

     chmod +r my_directory

   • Now you should be able to list the contents of "my_directory" once more.