Remove untracked files from the working tree

Given you have modified and untracked files:

# On branch master
# Changes not staged for commit:
#
#   modified:   Gemfile
#
# Untracked files:
#
#   docs/
#   file1.log

When you run: git clean -fd

Then you should have only the modified files:

# On branch master
# Changes not staged for commit:
#
#   modified:   Gemfile
#