#!/usr/bin/env perl

#builtin index can help you find substring

my $where = index('hello world', 'wo');
print $where;

@gSSHjail-> cat 02-rindex.pl
#!/usr/bin/env perl

my $f='/usr/local/bin/perl';

my $last=rindex($f, '/');
my $exe_cmd=substr($f, $last+1);

print $exe_cmd;
@