Python write to file in append or truncate mode

John D K -

Open the file in append mode or truncate mode can be set up by parameters like. Below you can find the most used ones:

  • w - Fully Truncate file or create new file for writing.
  • a - Open the file for writing ( create if does not exist ). Next writes of existing file are in append mode
  • r - Open file in reading mode.
  • b - opens the file in binary and append mode

There are some additional parameters like:

  • r+ - Read or write
  • w+ - Read or write ( create if doesn't exists otherwise truncate it )
  • a+ - Open for reading and writing. ( create if doesn't exists otherwise append to it )

Example in append mode:

with open("/home/myfile.txt", "a") as myfile:
    myfile.write("append this line")

Example in truncate mode:

with open("/home/myfile.txt", "w") as myfile:
    myfile.write("this is the first line of the file")

Example in truncate binary mode:

with open("myimage.png", "wb") as img:
    img.write(binary_data)

Some operations may require you to open the file in binary mode. When you need data as is without any transformations such as images, encodings etc