Question

write a perl program that counts the number of files in the working directory and the number of bytes in those files by file name

Answer 1

Program Code:

$ cat getsize.pl

#!/usr/bin/perl

# program to count the number of files in the working directory and number of bytes in those files, by filename extension

use strict;

use warnings;

# initializing num_of_files to zero and ext_hash(extension hash) to empty list

my $num_of_files = 0;

my %ext_hash=();

# assigning initial value to 0 for the key * which we will use for files with no extension

$ext_hash{'*'} = 0;

opendir my $dir, '.' or die "could not open directory: $!";

# reading files in the current directory

while (my $entry = readdir $dir){

# skipping if the file name is '.' or '..'

next if($entry eq '.' || $entry eq '..');

chomp($entry);

# splitting filename and extension so we have filename in fname variable and extension of it in ext variable.

my ($fname, $ext) = split(/\./, $entry, 2);

# counting number of files in the working directory

$num_of_files++;

# if no extension is available for filename, we should add the byte count to key '*' which we use for files with no extension

if (not defined $ext){

$ext_hash{'*'} = $ext_hash{'*'} + get_byte_count($entry);

next;

}

# for files with extension we will create extensions as keys to sum the total bytes of all the files with that extension

if (exists $ext_hash{$ext}){

$ext_hash{$ext} = $ext_hash{$ext} + get_byte_count($entry);

}

else{

$ext_hash{$ext} = get_byte_count($entry);

}

}

closedir($dir);

print "

";

print "Extension\tCount

";

# printing the filename extension byte count

foreach my $ext (keys %ext_hash){

print ".$ext", "\t\t", $ext_hash{$ext}, "

";

}

print "

Total number of files in the working directory: $num_of_files";

print "

";

# Method to get the byte count for a given file

# will not work for directories

sub get_byte_count{

# fetching the filename passed to the function

my $fname = shift;

my $wc = 0;

# opening the file in read mode

open(FH, "$fname") or die "$fname not able to open: $!";

# Iterating through each line in file and summing byte count

while(){

# summing byte count to wc variable by getting length of each line

$wc += length $_;

}

close(FH);

return $wc;

}