Ahh ... makes sense - thought that would help : I tried the echo experiment with cmdhist set and it put echo into history file as one (multi-line) entry - now reading it back in ... is a whole other beast ... this does not do exactly what you require but it does allow multi-line liners to be read back in as one line: after the first $hist substitution in addhist.pl :

$hist =~ s/\s+/ /gm;
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so I can now add (from history output):

...
   601  perl -MYAPE::Regex::Explain -e 'print 
        YAPE::Regex::Explain->new(qr/(aaaaa(?:(?:(?!aaaaa).)*))/s)->ex
+plain'
   602  addhist
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as:

perl -MYAPE::Regex::Explain -e 'print YAPE::Regex::Explain->new(qr/(aa
+aaa(?:(?:(?!aaaaa).)*))/s)->explain'
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to my ~/.oneliners file = thank you again for posting this script - I am a big fan of oneliners and this script is a big help in keeping them around longer than my histsize ...