Use of preg_replace

I need to be able to convert a line of the form: >>>From to have either one more or one less > at the front. A web site tells me that the regexps to use are: 1,$s/^>*From />&/ and 1,$s/^>(>*From )/\1/ respectively (there is a single space after "From"). So, if my text string is in $line, I ought to be able to do something like: $line = preg_replace ($pattern, $replacement, $line); But, since all regexps are to me, like TECO commands, no better than line-noise, how do I make up $pattern and $replacement from the proffered regexps? Thanks. -- Cheers -- Tim