# perl -c foobar
Bareword found where operator expected at foobar line 12, near "s/\s+/$letter++ . ' '/er"
syntax error at foobar line 12, near "s/\s+/$letter++ . ' '/er "
foobar had compilation errors.
root@facs04ap [/var/adm/scripts]
# perl -v

This is perl, v5.8.8 built for aix-thread-multi