You want to use Perl to process things on the command line but you don’t want to write/save a file. You want to replace sed with something more clunky. :)

[user@server tmp]$ ls / | perl -e 'while (){ print $_; }' bin boot dev etc home initrd lib lost+found misc mnt opt proc root sbin tmp usr var [user@server tmp]$ ls / | perl -e 'while (){ print "/" . $_; }' /bin /boot /dev /etc /home /initrd /lib /lost+found /misc /mnt /opt /proc /root /sbin /tmp /usr /var