  Background: Bots help automate many of the tasks performed by software
developers and are widely used to commit code in various social coding
platforms. At present, it is not clear what types of activities these bots
perform and understanding it may help design better bots, and find application
areas which might benefit from bot adoption. Aim: We aim to categorize the Bot
Commits by the type of change (files added, deleted, or modified), find the
more commonly changed file types, and identify the groups of file types that
tend to get updated together. Method: 12,326,137 commits made by 461 popular
bots (that made at least 1000 commits) were examined to identify the frequency
and the type of files added/ deleted/ modified by the commits, and association
rule mining was used to identify the types of files modified together. Result:
Majority of the bot commits modify an existing file, a few of them add new
files, while deletion of a file is very rare. Commits involving more than one
type of operation are even rarer. Files containing data, configuration, and
documentation are most frequently updated, while HTML is the most common type
in terms of the number of files added, deleted, and modified. Files of the type
"Markdown", "Ignore List", "YAML", "JSON" were the types that are updated
together with other types of files most frequently. Conclusion: We observe that
majority of bot commits involve single file modifications, and bots primarily
work with data, configuration, and documentation files. A better understanding
if this is a limitation of the bots and, if overcome, would lead to different
kinds of bots remains an open question.
