This is easier from the command line

perl -i.bak -pe's{/sbin/sh\s+/usr/adm/best1_default/bgs/scripts/best1a
+gent_start\s*>>\s*\$LOG\s+2>>\s*\$LOG\s*$} {/usr/bin/su - patrol /usr
+/adm/best1_default/bgs/scripts/best1agent -q}'
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you can use find to find the files that you want to change.

find <directory list> <predicates> -exec perl -i.bak -pe'...' {} \;
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If you are feeling very brave you can drop the .bak from the command line but it is safer to remove the backups after you have checked the result.

find <directory list> -name '*.bak' | xargs rm
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Disclaimer: I haven't run this command line on any of my files. I suggest you test it on a copy of a known bad file first.