I have a list of books inside a directory which I'm reading from and I want to list all words from the books that end with the lower and uppercase of a specific letter.

There's probably a way of doing it using cut or tr but I just can't think about it. Is there a way to use globs inside the pipe for it?

I'm not allowed to use grep, sed, awk, or perl.

Edit: The closest I got was:

cat * | tr '[:punct:]' ' '| tr ' ' '\n' | tr -s '\n'| tr '[:upper:]' '[:lower:]' | rev | sort

With this I can have the list of all words, one in each line. We don't really need to get rid of duplicates. Now I would just need to filter the words that have q in the beginning.

1 Answer 1


You could do something like:

< book.txt \
  tr -sc '[:alnum:]_-' '[\n*]' |
  tr -d - |
  rev |
  cut -c1 |
  tr -cd eE |
  fold -w1 |
  sort |
  uniq -c

To count the es and Es at the end of words (here defined as sequences of alphanumericals or underscores or hyphens), but note some of the limitations:

  • with many implementations including the GNU ones, that only works for single-byte characters.
  • rev, though common is not a standard command.
  • USA would be one word and U.S.A. three words.
  • even with implementations that work correctly with characters, it would count 2 es in Stéphane if the é was written in its decomposed form (e followed by U+0301 the combining acute accent).
  • it doesn't handle hyphenation.
  • it would count one e in 1.02e+23 or 0xffe.5fp-4...

If you were restricted to the POSIX shell and utilities, you could also use ed:

ed -s book.txt << 'EOF' | sort | uniq -c

Or with sh:

l=0 u=0
< book.txt \
  tr -sc '[:alnum:]_-' '[\n*]' | {
    while IFS= read -r word; do
      case $word in
        (*e) l=$((l + 1));;
        (*E) u=$((u + 1));;
    printf '%s\t%s\n' "$l" e "$u" E
  • Thank you for this! Why did you use fold for? I edited my main post with my partial solution. There's no problem considering U.S.A as three words.
    – dev0T
    Jan 23, 2021 at 18:08

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