How to change the permission of a file using Python?

File permissions determine which users can read, write, or execute a file. Python provides several methods to modify file permissions programmatically using the os.chmod() method and subprocess calls.

Using os.chmod() Method

The os.chmod() method changes file permissions by accepting a file path and permission mode ?

Syntax

os.chmod(path, mode)

Parameters:

• path ? The file or directory path
• mode ? Permission constants from the stat module

Return Value: None

Common Permission Constants

The stat module provides these permission constants ?

Example 1: Setting Basic Permissions

import os
import stat

# Create a test file
with open("test_file.txt", "w") as f:
    f.write("Hello World")

# Make file read-only for owner
os.chmod("test_file.txt", stat.S_IRUSR)
print("File set to read-only for owner")

# Make file readable and writable for owner
os.chmod("test_file.txt", stat.S_IRUSR | stat.S_IWUSR)
print("File set to read-write for owner")

File set to read-only for owner
File set to read-write for owner

Example 2: Using Octal Notation

import os

# Create a test file
with open("demo_file.txt", "w") as f:
    f.write("Demo content")

# Set permissions using octal notation
# 0o755 = rwxr-xr-x (owner: read,write,execute; group,others: read,execute)
os.chmod("demo_file.txt", 0o755)
print("Permissions set to 755 (rwxr-xr-x)")

# Set to read-only for all
os.chmod("demo_file.txt", 0o444)
print("Permissions set to 444 (r--r--r--)")

Permissions set to 755 (rwxr-xr-x)
Permissions set to 444 (r--r--r--)

Using subprocess.call() on Linux

On Unix-like systems, you can use the chmod command through subprocess ?

import subprocess

# Make file executable for owner only
subprocess.call(['chmod', '0700', 'script.sh'])

# Make file readable by all, writable by owner only
subprocess.call(['chmod', '0644', 'document.txt'])

Checking Current Permissions

import os
import stat

# Create a test file
with open("check_perms.txt", "w") as f:
    f.write("Test file")

# Get current permissions
file_stat = os.stat("check_perms.txt")
permissions = oct(file_stat.st_mode)[-3:]
print(f"Current permissions: {permissions}")

# Change permissions
os.chmod("check_perms.txt", 0o644)
file_stat = os.stat("check_perms.txt")
permissions = oct(file_stat.st_mode)[-3:]
print(f"New permissions: {permissions}")

Current permissions: 666
New permissions: 644

Conclusion

Use os.chmod() with stat constants or octal notation to change file permissions in Python. The method works across platforms, while subprocess.call() provides Unix-specific chmod functionality.