my $stdInfo="/home/stdInfo";
 
print " Enter the number of student that you want to delete\n";
my $std = <STDIN>;
#Don't forget to get rid of the newline character from the input
chomp $std;
 
#Open the file and read it in:
open(FILE, "$stdInfo") || die "couldn't open $stdInfo for reading";
#Each line is stored in an array
my @in=<FILE>;
close(FILE);

#Now open the same file again for output
open (FILE, ">$stdInfo") ||die "couldn't open $stdInfo for writing";

#Now print out everything except what you want to delete:
for (@in)
{
        print FILE unless ( $_ =~ /^$std/ );
}
close(FILE);