Programming Tutorials

chmod in Mac OS X

By: Strauss K in macos Tutorials on 2011-02-03  

chmod is a command-line utility used in Unix-based operating systems, including Mac OS X, to change the permissions of a file or directory. The chmod command allows you to specify who can read, write, and execute a file or directory. In Mac OS X, which is based on the Unix-like operating system, macOS, chmod is available in the Terminal application.

To use chmod, open the Terminal application and navigate to the directory where the file or directory you want to modify is located. Then, use the following command:

chmod [permissions] filename

Replace "permissions" with a three-digit code that specifies the permissions you want to set for the file or directory, and "filename" with the name of the file or directory that you want to modify. The three-digit code represents the permissions for the owner, group, and others, respectively. The first digit represents the owner's permissions, the second digit represents the group's permissions, and the third digit represents the permissions for all other users.

Here are the possible values for each digit:

• 0: No permission
• 1: Execute only
• 2: Write only
• 3: Write and execute
• 4: Read only
• 5: Read and execute
• 6: Read and write
• 7: Read, write, and execute

For example, if you want to give the owner read and write permissions, the group read-only permissions, and all other users no permissions, you would use the following command:

chmod 640 filename

After running this command, the permissions for the "filename" file would be set to "rw-r-----", which means that the owner has read and write permissions, the group has read-only permissions, and all other users have no permissions.