How Do I Convert Bytes Objects from External Commands to Strings in Python?

Encoding and Decoding Bytes in Python: A Guide to String Conversion

Bytes objects are commonly encountered when interacting with external programs or handling binary data. To work effectively with them, conversion to and from strings may be necessary. This article will address a specific problem regarding converting a bytes object containing the output of an external command to a regular Python string.

The Problem: Converting Bytes to String

Consider the following example from Python 3:

>>> from subprocess import *
>>> stdout = Popen(['ls', '-l'], stdout=PIPE).communicate()[0]
>>> stdout
b'total 0\n-rw-rw-r-- 1 thomas thomas 0 Mar  3 07:03 file1\n-rw-rw-r-- 1 thomas thomas 0 Mar  3 07:03 file2\n'

The stdout variable contains a bytes object representing the output of the 'ls -l' command. To print it in a human-readable format, it needs to be converted to a string.

Solution: Using the Decode Method

The decode() method is used to convert a bytes object to a string. It takes an encoding parameter, which specifies the character encoding of the data in the bytes object.

>>> stdout_str = stdout.decode('utf-8')
>>> print(stdout_str)
-rw-rw-r-- 1 thomas thomas 0 Mar  3 07:03 file1
-rw-rw-r-- 1 thomas thomas 0 Mar  3 07:03 file2

In this example, we specify 'utf-8' as the encoding because it is a common encoding for text data. However, it is important to use the correct encoding for the specific data being processed.

Note:

While the above solution works well for converting bytes objects representing text data, it is important to note that not all bytes objects contain text. For handling binary data, different techniques may be required.

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