Filecmp

Are two files equal in contents and metadata? It is sometimes useful to determine if a file is the same as another file. With filecmp, a Python module, this is possible.

Although it would be possible to implement the logic from filecmp in each program, filecmp offers convenient pre-built functionality. This reduces the amount of code you need to write.

Example

This program creates 2 separate files and populates them with some data. It then compares the files with the filecmp.cmp method.

Step 1 We use 2 open() calls to create two files (or rewrite the contents of any existing files with those names). We write some data to each.

Step 2 We compare the files with filecmp.cmp. This returns true, as the contents are equal.

Step 3 We modify the contents of the second file and write some text that is different to the file.

Step 4 When we call filecmp.cmp again, we get a False result as the files now have different contents.

import filecmp

f1 = "example.txt"
f2 = "example2.txt"

# Step 1: create the 2 files with identical text.
with open(f1, "w") as f:
    f.write("Some example text")

with open(f2, "w") as f:
    f.write("Some example text")

# Step 2: compare the files.
result = filecmp.cmp(f1, f2, shallow=True)
print(result)

# Step 3: modify the second file.
with open(f2, "w") as f:
    f.write("Different text")

# Step 4: compare the files again.
result = filecmp.cmp(f1, f2, shallow=True)
print(result)True
False

Summary

With the filecmp module, we have some useful methods like cmp and cmpfiles—these methods compare the metadata and (if necessary) the contents of files.