How about... 
cat file1 | perl -e 'while(<>){ next if !/IMO/; print $_;}'

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If the lines can only begin with IMO then: 
cat file1 | perl -e 'while(<>){ next if !/\bIMO/; print $_;}'

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If case is not important then: 
cat file1 | perl -e 'while(<>){ next if !/\bIMO/i; print $_;}'

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If you have multiple words to search for, then create another file named file2 and enter the search words: 
vi file2
apple
orange
banana

grep -f file2 file1

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From the unix command-line... file2 is the list of words to search for from lines in file1... Note: you may have to run "dos2unix file2" to remove LF/CR or use chomp somehow...

In reply to Re^2: what regular expression do I need? by tbone654
in thread what regular expression do I need? by Anonymous Monk

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