#!/usr/bin/perl
my @my_arr = ("test1", "test2", "test3", "test2", "test5", "test2", "test6");
my $what = 'test2';
my $then = 'best2';
foreach ( @my_arr ) {
s/^$what$/$then/ and last;
}
print $_, "\n" for @my_arr;
IyEvdXNyL2Jpbi9wZXJsCgpteSBAbXlfYXJyID0gKCJ0ZXN0MSIsICJ0ZXN0MiIsICJ0ZXN0MyIsICJ0ZXN0MiIsICJ0ZXN0NSIsICJ0ZXN0MiIsICJ0ZXN0NiIpOwpteSAkd2hhdCA9ICd0ZXN0Mic7Cm15ICR0aGVuID0gJ2Jlc3QyJzsKCmZvcmVhY2ggKCBAbXlfYXJyICkgewoJcy9eJHdoYXQkLyR0aGVuLyBhbmQgbGFzdDsKfQoKcHJpbnQgJF8sICJcbiIgZm9yIEBteV9hcnI7Cg==