Exercise: Implement the wc command of Linux/Unix (word count)
Exercise: Implement the wc command of Linux/Unix
See other exercises.
A sample execution of wc looks like this:
$ wc * 11 34 249 README.pod 2 4 128 authors.txt 37 110 773 check_examples.pl wc: examples: read: Is a directory 2737 2738 27627 python_weekly.pickle wc: sites: read: Is a directory 9 15 149 sites.yml wc: static: read: Is a directory 2796 2901 28926 total
That is. Given a list of things on the command line it counts the number of "lines", "words", and "characters" for each file printing them in 3 columns (in that order) followed by the name of the file.
At the end it will print the totals of each column.
If it encounters something that is not a file (e.g. a directory) it prints a warning and goes on.
In our case there were 3 directories 'examples', 'sites', and 'static'.
Optionally allow the user to supply any of the 3 flags: -l to print the line count, -w to print the word count, or -c to print the charater count. By default it prints all 3.
If no input file is provided, wc will work on the content arriving on the Standard Input. This means we can write this:
$ find . | wc -l
and get back the number of file in the directory tree starting in our current working directory.
Count words in a file is a simpler exercise. Solve that first!
Tools - Perl 5
- Perl 5: Open file and read content
- Perl 5: @ARGV
- Perl 5: warn
- Printing to STDERR
- Create functions
- Check file type (file, directory, etc)
Tools - Ruby
- Ruby: Open file and read content in Ruby
- Ruby: ARGV command line parameters
- Printing to Standard Error
Published on 2015-11-05