How can I get a file\'s permission mask using Python?

To get a file's permission mask in Python, use the os.stat() method from the os module. This method performs a stat system call on the given path and returns file information including permissions.

Basic Usage of os.stat()

The os.stat() function returns a 10-member tuple containing file metadata ?

import os

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

# Get file statistics
st = os.stat("sample.txt")
print("File stats tuple:", st)

File stats tuple: os.stat_result(st_mode=33188, st_ino=123456, st_dev=2049, st_nlink=1, st_uid=1000, st_gid=1000, st_size=11, st_atime=1640995200, st_mtime=1640995200, st_ctime=1640995200)

Extracting Permission Information

The first element st_mode contains the file permissions. You can access it using index [0] or the attribute name ?

import os

with open("sample.txt", "w") as f:
    f.write("Hello World")

st = os.stat("sample.txt")

# Get permission mask using index
mode_by_index = st[0]
print("Mode by index:", mode_by_index)

# Get permission mask using attribute (preferred)
mode_by_attr = st.st_mode
print("Mode by attribute:", mode_by_attr)

# Convert to octal format for readable permissions
octal_permissions = oct(st.st_mode)[-3:]
print("Octal permissions:", octal_permissions)

Mode by index: 33188
Mode by attribute: 33188
Octal permissions: 644

Using stat Module for Better Readability

The stat module provides constants to interpret file permissions more easily ?

import os
import stat

with open("sample.txt", "w") as f:
    f.write("Hello World")

st = os.stat("sample.txt")

# Extract just the permission bits
permissions = stat.S_IMODE(st.st_mode)
print("Permission mask:", oct(permissions))

# Check specific permissions
is_readable = bool(st.st_mode & stat.S_IRUSR)
is_writable = bool(st.st_mode & stat.S_IWUSR)
is_executable = bool(st.st_mode & stat.S_IXUSR)

print("Owner can read:", is_readable)
print("Owner can write:", is_writable)
print("Owner can execute:", is_executable)

Permission mask: 0o644
Owner can read: True
Owner can write: True
Owner can execute: False

Complete Permission Analysis

Here's a comprehensive example that displays all permission information ?

import os
import stat

def analyze_permissions(filepath):
    st = os.stat(filepath)
    mode = st.st_mode
    
    # Get octal representation
    octal_perms = oct(stat.S_IMODE(mode))
    
    # Check file type
    if stat.S_ISDIR(mode):
        file_type = "Directory"
    elif stat.S_ISREG(mode):
        file_type = "Regular file"
    else:
        file_type = "Other"
    
    print(f"File: {filepath}")
    print(f"Type: {file_type}")
    print(f"Permissions: {octal_perms}")
    print(f"Raw mode: {mode}")
    
    return mode

# Create and analyze a file
with open("test_file.txt", "w") as f:
    f.write("Test content")

analyze_permissions("test_file.txt")

File: test_file.txt
Type: Regular file
Permissions: 0o644
Raw mode: 33188

Conclusion

Use os.stat() to get file permissions in Python. Access the mode with st.st_mode or st[0], and use the stat module for better permission interpretation and analysis.