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I am having sometime here with my home assignment. Maybe you guys will advise what to read or what commands I can use in order to create the following:

Create a shell script test that will act as follows:

  1. The script will display the following message on the terminal screen: Enter file names (wild cards OK)
  2. The script will read the list of names.
  3. For each file on the list that is a proper file, display a table giving the ten most frequently used words in the file, sorted with the most frequent first. Include the count.
  4. Repeat steps 1-3 over and over until the user indicates end-of-file. This is done by entering the single character Ctrl-d as a file name.

Here is what I have so far:

#!/bin/bash
echo 'Enter file names (wild cards OK)'
read input_source
if test -f "$input_source"
then
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  • 1
    Please ask a single, specific question. IE not, "I'm not sure how to do this assignment.", but "How can I find the ten most frequently used words in a file?". Commented Apr 19, 2013 at 19:29
  • 1
    Let's start with the first part. You are supposed to read a list of names. Are you treating the input you get as a list (i.e. many things) or as a single item (i.e. one name)? How will it make a difference? Imagine I enter after your prompt: filename1 filename2 filename3. What does your test do with that input? Commented Apr 19, 2013 at 19:33
  • assuming there is a word per line: sort $input_source | uniq -c | head -10 Commented Apr 19, 2013 at 19:34
  • 1
    Also, if you are completely lost about shell scripting, I recommend that you take a look at something like this first: mywiki.wooledge.org/BashGuide. Commented Apr 19, 2013 at 19:34
  • @tigran …which would give you the ten least frequently used words in the file. Commented Apr 19, 2013 at 19:38

3 Answers 3

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I'm usually ignoring homework questions without showing some progress and effort to learn something - but you're as beautifully cheeky so i'll make an exception.

here is what you want

while read -ep 'Files?> ' files
do
    for file in $files
    do
        echo "== word counts for the $file =="
        tr -cs '[:alnum:]' '\n' < "$file" | sort | uniq -c | tail | sort -nr
    done
done

And now = at least try understand what the above doing...

Ps: voting to close...

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3 Comments

wow. Thanks. I am currently having couple of books opened regarding shell scripting :)
Your use of ls is adding a bug for files with whitespace: the file file with spaces will go through 3 iterations of the for loop.
Amended. This is the safest way to iterate over files.
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How to find the ten most frequently used words in a file

Assumptions:

  1. The files given have one word per line.
  2. The files are not huge, so efficiency isn't a primary concern.

You can use sort and uniq to find the count of non-unique values in a file, then tail to cut off all but the last ten, and reverse-numeric sort to put them in descending order.

sort "$afile" | uniq -c | tail | sort -rd
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Some tips:

  1. have access to the complete bash manual: it's daunting at first, but it's an invaluable reference -- http://www.gnu.org/software/bash/manual/bashref.html

  2. You can get help about bash builtins at the command line: try help read

  3. the read command can handle printing the prompt with the -p option (see previous tip)

  4. you'll accomplish the last step with a while loop:

    while read -p "the prompt" filenames; do 
    # ...
done
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