Shell Programming and Scripting

#!/bin/ksh
# splitem.sh
infile=$1
start=$2
end=$3
outfile=$4
awk -v start=$start -v end=$end ' NR>=start && NR <= end'  $infile > $outfile

./splitem myfile 1 5000 myfilefirst5000

#!/usr/bin/perl
# file name is cfil.pl
foreach $j (@ARGV) {
	die "bad j: $j\n" if ($j<1 or $j>100000) ;
	open($fh, '>', "$j.txt") or die $!;

	for($i=1; $i<=$j; $i++) {
		print $fh "Line $i of $j: Blah Blah Ha de blab blah\n";
	}
	close $fh or die $!;
}

$ cf.pl 10 20 50 100 1000 50000
$ wc -l *
      10 10.txt
     100 100.txt
    1000 1000.txt
      20 20.txt
      50 50.txt
   50000 50000.txt
   51180 total

#!/usr/bin/perl
use POSIX;
# file name is 3files.pl
$smp=.10;
$mp=.25;
$lp=.75;

foreach $name (@ARGV) {
	open($fh, '<',$name) or die $!;
	@contents=<$fh>;
	$lines= scalar @contents;
	
	$smlines=$mlines=$llines=0;
	
	print "$name has $lines lines\n";
	
	open($smfh, '>',"sm-$name") or die $!;
	open($mfh, '>', "mid-$name") or die $!;
	open($lfh, '>', "lg-$name") or die $!;
	for($l=0; $l<$lines; $l++) {
		if (fmod($l,1/$smp)<1) {
			$smlines++; 
			print $smfh $contents[$l];
		}
		
		if (fmod($l,1/$mp)<1) {
			$mlines++;
			print $mfh $contents[$l];
		}
		
		
		if (fmod($l,1/$lp)<1) {
			$llines++;
			print $lfh $contents[$l] ;
		}	
	}
	print "\tsm-$name has $smlines lines\n";
	print "\tmid-$name has $mlines lines\n";
	print "\tlg-$name has $llines lines\n\n"; 
	close $fh or die $!;
	close $smfh or die $!;
	close $mfh or die $!;
	close $lfh or die $!;
}	

$ 3files.pl *.txt

10.txt has 10 lines
	sm-10.txt has 1 lines
	mid-10.txt has 3 lines
	lg-10.txt has 7 lines

100.txt has 100 lines
	sm-100.txt has 10 lines
	mid-100.txt has 25 lines
	lg-100.txt has 75 lines

1000.txt has 1000 lines
	sm-1000.txt has 100 lines
	mid-1000.txt has 250 lines
	lg-1000.txt has 750 lines

20.txt has 20 lines
	sm-20.txt has 2 lines
	mid-20.txt has 5 lines
	lg-20.txt has 15 lines

50.txt has 50 lines
	sm-50.txt has 5 lines
	mid-50.txt has 13 lines
	lg-50.txt has 37 lines

50000.txt has 50000 lines
	sm-50000.txt has 5000 lines
	mid-50000.txt has 12500 lines
	lg-50000.txt has 37500 lines

#!/usr/bin/perl
use POSIX;
use warnings;
use strict;

# From Knuth Art of Programming
# Algortihm S(3.4.2)
# Select n records at random from a set of N records where
# 0<n<=N
sub selection_sample {
    my ($array,$num)=@_;
    die "Too few elements (".scalar(@{$array}).") to select $num from\n"
        unless $num<@{$array};
    my @result;
    my $pos=0;
    while (@result<$num) {
        $pos++ while (rand(@{$array}-$pos)>($num-@result));
        push @result,$array->[$pos++];
    }
    return \@result
}

my $smp=.10;
my $mp=.25;
my $lp=.75;
my $smlines=0;
my $mlines=0;
my $llines=0;
my $klines=0;
my @contents;
my $knuth;
my $klines=0;
my $line;
my $lines;

foreach my $name (@ARGV) {
	open(my $fh, '<',$name) or die $!;
	@contents=<$fh>;
	$lines= scalar @contents;
	
	print "$name has $lines lines\n";
	
	open(my $smfh, '>',"sm-$name") or die $!;
	open(my $mfh, '>', "mid-$name") or die $!;
	open(my $lfh, '>', "lg-$name") or die $!;
	
	for($line=0; $line<$lines; $line++) {
		if (fmod($line,1/$smp)<1) {
			$smlines++; 
			print $smfh $contents[$line];
		}
		
		if (fmod($line,1/$mp)<1) {
			$mlines++;
			print $mfh $contents[$line];
		}
		
		
		if (fmod($line,1/$lp)<1) {
			$llines++;
			print $lfh $contents[$line] ;
		}	
	}
	
	open(my $kfh, '>', "k-$name") or die $!;	
	$knuth=selection_sample(\@contents,60) ;
	foreach $line (@{$knuth}) {
		$klines++;
		print $kfh $line;
	}

	print "\tsm-$name has $smlines lines\n";
	print "\tmid-$name has $mlines lines\n";
	print "\tlg-$name has $llines lines\n";
	print "\tk-$name has $klines lines \n\n";
	close $fh or die $!;
	close $smfh or die $!;
	close $mfh or die $!;
	close $lfh or die $!;	
	close $kfh or die $!;
}