Append Content of One Text File to Another - Python

Given two text files, the task is to append the entire content of the second file (source) to the end of the first file (target) using Python.

file1.txt

file2.txt

After appending file2 -> file1:

geeksforgeeks

Using shutil.copyfileobj()

This method is the most efficient for large files. It copies data in chunks directly from one file to another.

Output

geeksforgeeks

Explanation:

• open('file2.txt', 'r'): Opens source file in read mode
• open('file1.txt', 'a'): Opens target file in append mode
• shutil.copyfileobj(f2, f1): Copies content from file2 to file1 efficiently

Using File Object (read() + write())

This method reads the entire content of the source file at once using read() and appends it to the target file using write().

Output

geeksforgeeks

Explanation:

• open('file2.txt', 'r'): Opens source file in read mode
• f2.read(): Reads entire content of file2
• open('file1.txt', 'a'): Opens target file in append mode
• f1.write(data): Appends file2 content to file1

Using fileinput Module

This method is useful when processing multiple input files line by line, but it is less readable and rarely needed for simple appending.

Output

geeksforgeeks

Explanation:

• fileinput.input(): Iterates over lines of the source file
• f1.write(line): Appends each line to the target file

Related Articles:

• Copy Contents of One File to Another File - Python
• Python append to a file