1. Split the input into words, one per line.
2. Sort the resulting list of words (lines).
3. Squash multiple occurences.
4. Sort by occurrence count.

To split the input into words, replace any character that you deem to be a word separator by a newline.

<input_file \
tr -sc '[:alpha:]' '\n' |   # Add digits, -, \', ... if you consider them word constituents
sort |
uniq -c |
sort -k 1nr

1. Split the input into words, one per line.
2. Sort the resulting list of words (lines).
3. Squash multiple occurences.
4. Sort by occurrence count.

To split the input into words, replace any character that you deem to be a word separator by a newline.

<input_file \
tr -sc '[:alpha:]' '[\n*]' | # Add digits, -, ', ... if you consider
                             # them word constituents
sort |
uniq -c |
sort -nr