Shell Programming and Scripting

awk '
{a[NR]=$0}
/pattern/{ 
   for(i=10;i>=1;i--){
    print a[NR-i]
   }
   for ( j=1;j<=NR-10;j++){
    delete a[j]
   }
} 
' "file"

nawk '{
line[NR]=$0
if (index($0,"pattern")!=0)
for (i=NR-10;i<=NR;i++)
print line[i]
}' filename

for x in `grep -n "pattern" <filename> |cut -d":" -f1`
do
head -$x <filename> | tail -10
done

#!/usr/bin/perl
use strict;
use warnings;
use Tie::File;
use Fcntl 'O_RDONLY';

tie my @file, 'Tie::File', 'path/to/file', mode => O_RDONLY
    or die "Can't open path/to/file: $!";
foreach my $i (10 .. $#file) {
    if ($file[$i] =~ /pattern/) {
        print qq{"pattern" found on line },$i+1,"$/";
        print qq{previous ten lines:$/}; 
        print map{"$_$/"} @file[$i-10 .. $i-1], "----------------------------";
    }
}