Once you have installed Flake8, you can begin using it. Most of the time, you will be able to generically invoke Flake8 like so:
Where you simply allow the shell running in your terminal to locate Flake8. In some cases, though, you may have installed Flake8 for multiple versions of Python (e.g., Python 3.8 and Python 3.9) and you need to call a specific version. In that case, you will have much better results using:
python3.8 -m flake8
python3.9 -m flake8
Since that will tell the correct version of Python to run Flake8.
Installing Flake8 once will not install it on both Python 3.8 and Python 3.9. It will only install it for the version of Python that is running pip.
It is also possible to specify command-line options directly to Flake8:
flake8 --select E123
python<version> -m flake8 --select E123
This is the last time we will show both versions of an invocation.
From now on, we’ll simply use
flake8 and assume that the user
knows they can instead use
python<version> -m flake8 instead.
It’s also possible to narrow what Flake8 will try to check by specifying
exactly the paths and directories you want it to check. Let’s assume that
we have a directory with python files and sub-directories which have python
files (and may have more sub-directories) called
my_project. Then if
we only want errors from files found inside
my_project we can do:
And if we only want certain errors (e.g.,
E123) from files in that
directory we can also do:
flake8 --select E123 my_project
If you want to explore more options that can be passed on the command-line,
you can use the
And you should see something like:
Usage: flake8 [options] file file ... Options: --version show program's version number and exit -h, --help show this help message and exit -v, --verbose Print more information about what is happening in flake8. This option is repeatable and will increase verbosity each time it is repeated. -q, --quiet Report only file names, or nothing. This option is repeatable. --count Print total number of errors and warnings to standard error and set the exit code to 1 if total is not empty. --diff Report changes only within line number ranges in the unified diff provided on standard in by the user. --exclude=patterns Comma-separated list of files or directories to exclude.(Default: .svn,CVS,.bzr,.hg,.git,__pycache__,.tox,.eggs,*.egg) --filename=patterns Only check for filenames matching the patterns in this comma-separated list. (Default: *.py) --format=format Format errors according to the chosen formatter. --hang-closing Hang closing bracket instead of matching indentation of opening bracket's line. --ignore=errors Comma-separated list of errors and warnings to ignore (or skip). For example, ``--ignore=E4,E51,W234``. (Default: E121,E123,E126,E226,E24,E704) --extend-ignore=errors Comma-separated list of errors and warnings to add to the list of ignored ones. For example, ``--extend- ignore=E4,E51,W234``. --max-line-length=n Maximum allowed line length for the entirety of this run. (Default: 79) --select=errors Comma-separated list of errors and warnings to enable. For example, ``--select=E4,E51,W234``. (Default: ) --extend-select errors Comma-separated list of errors and warnings to add to the list of selected ones. For example, ``--extend- select=E4,E51,W234``. --disable-noqa Disable the effect of "# noqa". This will report errors on lines with "# noqa" at the end. --show-source Show the source generate each error or warning. --statistics Count errors and warnings. --enabled-extensions=ENABLED_EXTENSIONS Enable plugins and extensions that are otherwise disabled by default --exit-zero Exit with status code "0" even if there are errors. -j JOBS, --jobs=JOBS Number of subprocesses to use to run checks in parallel. This is ignored on Windows. The default, "auto", will auto-detect the number of processors available to use. (Default: auto) --output-file=OUTPUT_FILE Redirect report to a file. --tee Write to stdout and output-file. --append-config=APPEND_CONFIG Provide extra config files to parse in addition to the files found by Flake8 by default. These files are the last ones read and so they take the highest precedence when multiple files provide the same option. --config=CONFIG Path to the config file that will be the authoritative config source. This will cause Flake8 to ignore all other configuration files. --isolated Ignore all configuration files. --builtins=BUILTINS define more built-ins, comma separated --doctests check syntax of the doctests --include-in-doctest=INCLUDE_IN_DOCTEST Run doctests only on these files --exclude-from-doctest=EXCLUDE_FROM_DOCTEST Skip these files when running doctests Installed plugins: pyflakes: 1.0.0, pep8: 1.7.0