On 2/3/06, Paul Howarth <paul@xxxxxxxxxxxx> wrote: > Dan Track wrote: > > Just wondering if you could exaplin something to me: > > > > 1) What does the following mean in plain english ^\(Target\[[^]]*\]. > > I'm getting confused by the number of "[" brackets. To be specific I > > can't see how this part \[[^]]*\] is working. The \[ indicates the > > match to the "[" string but what I read from [^]] here is that I want > > the regular expression to match any of these ^] charaters. But there > > isn't a ^ charater or a ]. > > I'll take it element by element. > > ^ = Anchor the expression to the start of a line, > > \( ... \) = sed "remembers" whatever matches the expression between \( > and \) and will use that text in the replacement part of the > search-and-replace - a "\1" means the first "remembered" text, a "\2" > means the second "remembered" text etc. > > Terget = boilerplate text to be matched > > \[ = match the literal character "[" > > [^]] = match any character except "]" > > > 2) What does $!N mean. > > I pulled this from the sed FAQ, which explains it better than I could: > > http://www.student.northpark.edu/pemente/sed/sedfaq4.html#s4.23.2 > > Note that the 'N' followed by the 'P;D;' commands forms a "sliding > window" technique. A window of N lines is formed. If the multi-line > pattern matches, the block is handled. If not, the top line is printed > and then deleted from the pattern space, and we try to match at the > next line." > > $!N literally means "if we're not at the end of the file, read the next > line into the pattern space" > Thanks very much for your time and help. I've learnt a lot from this. Thanks Dan
