On Tuesday 25 September 2007 06:07, Howard Goldstein wrote: > Gary Kline wrote: > > My earlier post about deleting the first N lines was answered by > > this one-liner site {below}. I wasn't including any > > redirection; doing so finally resolved the problem. Now I need > > to delete every line from the 19th or so to the last line.
sed -e 18q that is, quit after processing line 18. > > Question one, can anybody explain the following syntax? What do > > "P", "D" "ba" represent, in other words? The manual page explains sed in a very good way. For sure, better than I could describe it here. You'd better read it. > > > > > > # delete the last 10 lines of a file > > sed -e :a -e '$d;N;2,10ba' -e 'P;D' # method 1 > > sed -n -e :a -e '1,10!{P;N;D;};N;ba' # method 2 > > > > > > Question two, can sed do its thing inline? Yes. -i extension Edit files in-place, saving backups with the specified extension. If a zero-length extension is given, no backup will be saved. It is not recommended to give a zero-length extension when in-place editing files, as you risk corruption or partial content in situ- ations where disk space is exhausted, etc. > > Wouldn't it be easier to use head -n 18 ? No, it's the same. Some sed operation are trivial to read/write, others aren't. HTH Nikos _______________________________________________ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"