just cheat and make sure the input doesn't have more than one per line :)
tr ' ' '\n' < /tmp/hh | grep -c hello
alternatives:
plain, explicit count (leverage s/// to provide # per line):
perl -lne '$ct += s/hello//g; END {print $ct}' /tmp/hh
Same technique as the tr/grep above, just in perl flavor:
perl -0040 -ne 'END {print "$x\n"} $x++ if /hello/' /tmp/hh
Fun w/
perlrun:
perl -Fhello -0777 -lane 'print $#F' /tmp/hh
# shorter:
perl -apFhello -0777e '$_=$#F' < /tmp/hh
# with check for word boundry (e.g. to exclude "Othello" or mispelled
+"cello")
perl -apF'\bhello\b' -0777e '$_=$#F' < /tmp/hh