Fairly easily. Personally by this point I'd have long resorted to Perl, so the the usage of 'tr' and 'sed' in other than the most trivial ways aren't something that I'm very familiar with. But here's how I parse it without looking at man:
1. We're substituting characters and we're looking for is all word characters, and what we replace with is a newline. That doesn't seem terribly useful at a first glance, so either -c or -s is probably a negation. So this probably splits by words, producing newline separated words.
2. Change A-Z into a-z, that's obviously uppercase to lowercase. Confirms that text is what we're working with.
3. Sort alphabetically.
4. Remove duplicates and count.
5. Sort numerically.
6. Not entirely sure what 'sed ${N}q` does.
So yeah, I can get most of the way there without looking at the manual at all, making the reasonable guess that it results in a list of words sorted by frequency. My main point of confusion would be with sed, because it's hard to search manuals for the meaning of 'q' and I'd have used 'head' instead. Looking up what's the deal with 'tr' is about 5 seconds.
I'm pretty sure sed ${N}q is supposed to chose the N (or k) top choices, where N is given as an argument/variable.
(Going off of the fact that head is essentially sed 11q, where it quits on the 11th line.)
But yeah, head -n (--lines) would do the job here perfectly while being more readable, no clue why it wasn't used.
1. We're substituting characters and we're looking for is all word characters, and what we replace with is a newline. That doesn't seem terribly useful at a first glance, so either -c or -s is probably a negation. So this probably splits by words, producing newline separated words.
2. Change A-Z into a-z, that's obviously uppercase to lowercase. Confirms that text is what we're working with.
3. Sort alphabetically.
4. Remove duplicates and count.
5. Sort numerically.
6. Not entirely sure what 'sed ${N}q` does.
So yeah, I can get most of the way there without looking at the manual at all, making the reasonable guess that it results in a list of words sorted by frequency. My main point of confusion would be with sed, because it's hard to search manuals for the meaning of 'q' and I'd have used 'head' instead. Looking up what's the deal with 'tr' is about 5 seconds.