To process a document with the spell checker, use sphinx-build and specify spelling as the builder name using the -b option. The output includes the headings from the document and any misspelled words. If suggestions are enabled, they are shown on the same line as the misspelling. A log of the words in each input file not found in the dictionary is saved to the file <input>.spelling under the build directory.

$ tox -e spelling -r
spelling create: .../sphinxcontrib-spelling/.tox/spelling
spelling installdeps: .[docs]
spelling develop-inst: .../sphinxcontrib-spelling
spelling installed: -f /Users/dhellmann/.pip/wheelhouse,alabaster==0.7.12,Babel==2.8.0,certifi==2020.6.20,chardet==3.0.4,docutils==0.16,dulwich==0.20.5,idna==2.10,imagesize==1.2.0,importlib-metadata==1.7.0,Jinja2==2.11.2,MarkupSafe==1.1.1,packaging==20.4,pbr==5.4.5,pyenchant==3.1.1,Pygments==2.6.1,pyparsing==2.4.7,pytz==2020.1,PyYAML==5.3.1,reno==3.1.0,requests==2.24.0,six==1.15.0,snowballstemmer==2.0.0,Sphinx==3.2.0,sphinxcontrib-applehelp==1.0.2,sphinxcontrib-devhelp==1.0.2,sphinxcontrib-htmlhelp==1.0.3,sphinxcontrib-jsmath==1.0.1,sphinxcontrib-qthelp==1.0.3,sphinxcontrib-serializinghtml==1.1.4,-e,urllib3==1.25.10,zipp==3.1.0
spelling run-test-pre: PYTHONHASHSEED='1632297322'
spelling run-test: commands[0] | sphinx-build -W -j auto -b spelling -d docs/build/doctrees docs/source docs/build/spelling
Running Sphinx v3.2.0
Initializing Spelling Checker 5.2.1.dev2
Ignoring wiki words
Ignoring acronyms
Adding package names from PyPI to local dictionary…
Ignoring Python builtins
Ignoring importable module names
Adding contents of .../sphinxcontrib-spelling/docs/source/spelling_wordlist.txt to custom word list
Adding contents of .../sphinxcontrib-spelling/docs/source/spelling_people.txt to custom word list
Looking for custom word list in /var/folders/5q/8gk0wq888xlggz008k8dr7180000hg/T/tmphsetrn0s/spelling_wordlist.txt
building [mo]: targets for 0 po files that are out of date
building [spelling]: all documents
updating environment: [new config] 6 added, 0 changed, 0 removed
reading sources... [ 16%] customize
reading sources... [ 33%] developers
reading sources... [ 50%] history
reading sources... [ 66%] index
reading sources... [ 83%] install
reading sources... [100%] run

waiting for workers...
scanning .../sphinxcontrib-spelling/releasenotes/notes for current branch release notes
got versions ['5.2.0']
looking for now-outdated files... none found
pickling environment... done
checking consistency... done
preparing documents... done
writing output... [ 16%] customize
Extending local dictionary for customize
writing output... [ 33%] developers
Extending local dictionary for developers
writing output... [ 50%] history
Extending local dictionary for history
writing output... [ 66%] index
Extending local dictionary for index
index.rst:17:speel:["Peel", "peel", "spell", "spiel", "Speer", "speed", "steel", "sepal", "spill", "spoil", "spool", "speller", "Pele", "supple", "Perl", "spew", "spree", "suppl", "repel", "spells", "spiels", "spleen", "peal", "seal", "seep", "sell", "Aspell", "Ispell", "sleep", "spell's", "spiel's"]:I can't speel.
Writing .../sphinxcontrib-spelling/docs/build/spelling/index.spelling
writing output... [ 83%] install
Extending local dictionary for install
writing output... [100%] run

Warning, treated as error:
Found 1 misspelled words
ERROR: InvocationError for command .../sphinxcontrib-spelling/.tox/spelling/bin/sphinx-build -W -j auto -b spelling -d docs/build/doctrees docs/source docs/build/spelling (exited with code 2)
__________________________________________________ summary ___________________________________________________
ERROR:   spelling: commands failed