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From: emv@math.lsa.umich.edu (Edward Vielmetti)
Newsgroups: comp.unix.questions,comp.unix.shell,comp.lang.perl
Subject: Re: Counting characters with unix utilities
Message-ID: <EMV.90Sep23181658@picasso.math.lsa.umich.edu>
Date: 23 Sep 90 22:16:58 GMT
References: <4002@umbc3.UMBC.EDU>
Sender: usenet@math.lsa.umich.edu
Organization: University of Michigan Math Dept., Ann Arbor MI.
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In-Reply-To: rouben@math9.math.umbc.edu's message of 23 Sep 90 20:34:26 GMT

In article <4002@umbc3.UMBC.EDU> rouben@math9.math.umbc.edu writes:

   How can I count the number of occurrences of a given character in a file?
   It can be done rather trivially in C, but I wonder if it can also be done
   using standard unix utilities like awk, sed, tr, wc, etc.

   The closest  I have come to this is the following construction:

   cat file | tr -c 'A' '' | wc -c

This is what I came up with in perl, after about 15 minutes of digging
in the perl info pages:

   cat file | perl -ne '$c += tr/A/A/; if (eof()) {print "$c\n";}'

Going back to the tr man page this one seems to work too:

   cat file | tr -cd 'A' | wc -c

I don't see an easy perl equivalent of the "tr -cd" idiom.

--Ed

Edward Vielmetti, U of Michigan math dept <emv@math.lsa.umich.edu>
moderator, comp.archives