Question

16

What is a practical way to list every character used in a file (Bash) (Regex)

rated 0 times [ 16] [ 0] / answers: 1 / hits: 6195 / 3 Years ago, sun, june 20, 2021, 5:11:06

How can I turn this:

Johnny's penguin, (Tuxie), likes the following foods: French fries, and beef.

To this:

 abcdefghiklnoprstuwFJT',():.

(These are the total characters used in the input)

Please note that the small case characters "jmqvz" were not in the input sentence, therefore, not outputted.

The order is not important whatsoever, but lower case, then upper case, then special characters will be preferred.

I am certain I will need sed/awk/etc. for this, but I have not found anything similar after extensive searching.

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atereress

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3 Years ago

answered 3 Years ago steaocyte · Accepted Answer

You can use a combination of sed and sort:

$ echo "Johnny's penguin, (Tuxie), likes the following foods: French fries, and beef." | 

>  sed 's/./&

/g' | LC_COLLATE=C sort -u | tr -d '

'

 '(),.:FJTabcdefghiklnoprstuwxy

sort does lexicographic sorting, so see man 7 ascii to see how the characters will order up.

Explanation:

sed 's/./& /g' - add a newline after every character, since sort (usually) does line-by-line sorting

LC_COLLATE=C sets the collation style to C (see What does “LC_ALL=C” do?)

sort -u: sorts the input and prints only the unique entries

tr -d ' ' deletes all the extra new lines.

If you want to keep only visible characters:

$ echo "Johnny's penguin, (Tuxie), likes the following foods: French fries, and beef." | 

> tr -cd '[[:graph:]]' | sed 's/./&

/g' | LC_COLLATE=C sort -u | tr -d '

'

tr -cd '[[:graph:]]' deletes everything except visible characters.