For filenames, are underscores or dashes more common in Unix file names?

Question

When you are naming files with multiple words in the name, is it more common in Unix systems to use underscores, camel case, or dashes to separate the words?

Answer 1

On one of my random systems:

$ find /usr/bin -xdev -type f -name '*-*' | wc -l                # hyphen
1019
$ find /usr/bin -xdev -type f -name '*_*' | wc -l                # underscore
311
$ find /usr/bin -xdev -type f -name '*[a-z][A-Z][a-z]*' | wc -l  # camelcase
2
$ find /usr/bin -xdev -type f -name '* *' | wc -l                # space
0

Your mileage may vary. There's a lot of personal preference involved -- my home directory is probably very much skewed towards hyphens, because underscore and camelcase involves shifting, and space has difficulties with quoting.