just cheat and make sure the input doesn't have more than one per line :) 
tr ' ' '\n' < /tmp/hh | grep -c hello

[download]
alternatives:

plain, explicit count (leverage s/// to provide # per line): 
perl -lne '$ct += s/hello//g; END {print $ct}' /tmp/hh

[download]
Same technique as the tr/grep above, just in perl flavor: 
perl -0040 -ne 'END {print "$x\n"} $x++ if /hello/' /tmp/hh

[download]
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

[download]

In reply to Re^2: grep command by davidrw
in thread grep command by sanku

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