Managing file permissions is essential for controlling access to files and directories on macOS. If you need to change read, write permissions on Mac Terminal, this guide will walk you through the process in detail. Whether you’re a beginner or an advanced user, understanding how to modify file permissions using the command line can help you secure your system and troubleshoot issues effectively.

Understanding File Permissions on macOS

On macOS, every file and folder has associated permissions that determine who can read, write, or execute them. These permissions are based on the Unix file system model and are categorized into three types:

1. Owner (User) – The user who owns the file.
2. Group – A set of users who share access to the file.
3. Others – Everyone else who has access to the system.

Each file or directory has three types of permissions:

• Read (r) – Allows viewing the file contents.
• Write (w) – Permits editing or modifying the file.

Execute (x) – Enables running the file as a program (applicable for scripts or executables).

Viewing File Permissions in Mac Terminal

To check the permissions of a file or directory, use the ls -l command in the Terminal:

ls -l filename

Example output:

-rw-r--r--  1 username  staff  1234 Mar 14 10:30 myfile.txt

Breaking down the output:

• -rw-r--r-- – The file permissions.
• 1 – The number of links to the file.
• username – The file owner.
• staff – The user group.
• 1234 – File size in bytes.
• Mar 14 10:30 – Last modified date.
• myfile.txt – File name.

How to Change File Permissions on Mac Using Terminal

1. Changing Permissions with chmod

The chmod command is used to change permissions. You can modify permissions using numeric (octal) mode or symbolic mode.

Using Numeric Mode

Each permission type is represented by a number:

• Read (r) = 4
• Write (w) = 2
• Execute (x) = 1

To set specific permissions, sum the values:

• chmod 644 filename – Owner can read/write, others can read.
• chmod 755 filename – Owner has all permissions, others can read/execute.
• chmod 777 filename – Everyone has full permissions (not recommended for security reasons).

Example:

chmod 644 myfile.txt

Using Symbolic Mode

Symbolic mode allows more flexibility:

• u (user/owner)
• g (group)
• o (others)
• a (all)

Example:

chmod u+w myfile.txt  # Grants write permission to the owner
chmod g-r myfile.txt  # Removes read permission for the group
chmod o+x myscript.sh # Grants execute permission to others

2. Changing Ownership with chown

To change the owner of a file or directory, use the chown command:

sudo chown newuser filename

To change both owner and group:

sudo chown newuser:newgroup filename

Example:

sudo chown john:staff myfile.txt

3. Changing Group Ownership with chgrp

If you only want to change the group ownership:

sudo chgrp newgroup filename

Example:

sudo chgrp admin myfile.txt

Modifying Directory Permissions

To change permissions for directories, use the chmod command with the -R flag to apply changes recursively:

chmod -R 755 mydirectory

To change ownership recursively:

sudo chown -R newuser:newgroup mydirectory

Common Permission Issues and Fixes

1. Permission Denied Error

If you see a Permission denied error, try using sudo:

sudo chmod 755 filename

2. Restoring Default Permissions

To reset file permissions:

chmod 644 filename

For directories:

chmod 755 directoryname

3. Fixing Permissions for All Files in a Directory

To reset all file permissions to 644 and directory permissions to 755:

find /path/to/directory -type f -exec chmod 644 {} \;
find /path/to/directory -type d -exec chmod 755 {} \;

Using macOS Finder to Change Permissions

If you prefer a graphical interface, you can modify file permissions using Finder:

1. Right-click the file/folder and select Get Info.
2. Expand the Sharing & Permissions section.
3. Adjust permissions for users and groups.
4. Click the lock icon and enter your password if needed.

Conclusion

Learning how to change read, write permissions on Mac Terminal is crucial for managing file security and access control. Using chmod, chown, and chgrp, you can easily modify permissions, set ownership, and troubleshoot access issues. Whether you need to grant, restrict, or reset permissions, the Terminal provides powerful commands to handle file management efficiently. Mastering these commands will enhance your macOS experience and ensure better control over your system’s security.