Append binary file to another binary file

Question

I want to append a previously-written binary file with a more recent binary file created. Essentially merging them. This is the sample code I am using:

with open("binary_file_1", "ab") as myfile:
    myfile.write("binary_file_2")

Except the error I get is "TypeError: must be string or buffer, not file"

But that's exactly what I am wanting to do! Add one binary file to the end of an earlier created binary file.

I did try adding "wb" to the "myfile.write("binary_file_2", "wb")but it didn't like that.

I doubt that your code produces that error. Can you post your actual code? See Minimal, Complete, and Verifiable example... — Tim Pietzcker
– Tim Pietzcker, Commented Sep 18, 2014 at 11:22

mhawke · Accepted Answer · 2014-09-18 11:33:04Z

24

You need to actually open the second file and read its contents:

with open("binary_file_1", "ab") as myfile, open("binary_file_2", "rb") as file2:
    myfile.write(file2.read())

answered Sep 18, 2014 at 11:33

mhawke

87.5k10 gold badges122 silver badges142 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

user7504939 Over a year ago

This is great, the first file doesn't need to exist before hand either, so you can start from nothing.

Robert Ribas · Accepted Answer · 2019-07-05 09:33:10Z

8

From the python module shutil

import os
import shutil

WDIR=os.getcwd()
fext=open("outputFile.bin","wb")
for f in lstFiles:
    fo=open(os.path.join(WDIR,f),"rb")
    shutil.copyfileobj(fo, fext)
    fo.close()
fext.close()

First we open the the outputFile.bin binary file for writing and then I loop over the list of files in lstFiles using the shutil.copyfileobj(src,dest) where src and dest are file objects. To get the file object just open the file by calling open on the filename with the proper mode "rb" read binary. For each file object opened we must close it. The concatenated file must be closed as well. I hope it helps

answered Jul 5, 2019 at 9:33

Robert Ribas

3173 silver badges7 bronze badges

2 Comments

chronos Over a year ago

This should be the accepted answer, as the one currently accepted tries to read all the data before writing it (which will cause problems for big files)

debashish.ghosh Over a year ago

A context-manager variant of this answer would be a great answer.

Max Gómez · Accepted Answer · 2018-03-21 17:48:54Z

1

for file in files:
    async with aiofiles.open(file, mode='rb') as f:
        contents = await f.read()
    if file == files[0]:
        write_mode = 'wb'  # overwrite file
    else:
        write_mode = 'ab'  # append to end of file

    async with aiofiles.open(output_file), write_mode) as f:
        await f.write(contents)

answered Mar 21, 2018 at 17:48

Max Gómez

696 bronze badges

1 Comment

Mathews Sunny Over a year ago

Add some description to your code. The logic would be more helpful than mere piece of code.

Collectives™ on Stack Overflow

Append binary file to another binary file

3 Answers 3

1 Comment

2 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

2 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related