Why grep command doesn't work within perl script

Question

The following staement in perl throws an error

my $string =qx(ls grep test) ;

…where test is some file name to be searched...

But the following statements doen't through an error

my $string =qx(ls) ;

I am working in unix solaris machine

Answer 1

Did you mean this?

my $string =qx(ls | grep test) ;