UNIX for Dummies Questions & Answers

#! /usr/bin/ksh
file=somefilename
N=$(wc -l < $file|sed 's/ //g')
awk -v N=$N 'BEGIN { for (i=1; i<=10; i++)  printf "%.0fp\n", N*rand() ; exit } ' |sort -n |\
sed '$s/p/{p;q;}/' > tempfile
sed -n -f tempfile $file
rm tempfile
exit 0

#!/bin/ksh93

TMP=file.$$

cat <<EOT >$TMP
aaa
bbb
ccc
ddd
eee
fff
ggg
hhh
EOT

command exec 3<> $TMP

for i in 0 8 12 20
do
   if (( $(3<# ((${i}))) != ${i} ))
   then
      print "ERROR: Not at position $i"
      exit 1
   else
      read -u3 LINE
      print $LINE
   fi
done

rm $TMP
exit 0

    use Algorithm::Numerical::Sample  qw /sample/;

    $sampler
      = Algorithm::Numerical::Sample::Stream->new( sample_size => $n );
    while (<$FILE>) {
      $sampler->data($_);
    }
    @a = $sampler->extract;
    print @a;