On Tue, 15 Oct 2019 12:48:17 +1100 "Trent W. Buck" <trentb...@gmail.com> wrote:
> Package: grep > Version: 3.3-1 > Severity: wishlist > > This bug was originally reported as > https://bugs.debian.org/940464 > > Trent W. Buck wrote: > > (Surely someone has already asked for this, but I can't see where. > > I may have already reported this myself, and forgotten. > > If so, sorry!) > > > > Right now if you do > > > > grep -eX -eY -eZ > > > > You'll get lines that match *any of* X, Y, or Z. > > Quite often I want to search for lines that match *all of* X, Y, and Z ? > > but in any order. > > For example, > > > > # all 4TB 2.5-inch SATA products > > grep -Fwi -eSATA -e2TB -e2.5in products.csv > > > > Below is a short discussion of the workarounds I know about. > > > > Is "grep --and" something that has already been discussed and rejected? > > I looked through debbugs.gnu.org and the source tarball, but > > I couldn't find anything about this. > > > > > > PS: grep -v --and would intuitively mean "not all", > > i.e. "grep -v --and -eX -eY" would return lines matching X *or* Y, but > > omit lines matching *both* X and Y. > > > > PS: I can't decide if "--and" or "--intersection" is a better name. > > I put both in the bug subject so people searching for either will find this > > ticket. > > I think "--all" is probably too confusing. > > > > > > > > Workaround #1 > > ============= > > I can work around this by listing every possible order, but 1) this > > scales poorly with the number of patterns; and 2) it can't be used > > with -F. For example, > > > > grep --and -eX -eY -eZ input*.txt # becomes > > > > grep -eZ.*Y.*X \ > > -eZ.*X.*Y \ > > -eY.*Z.*X \ > > -eY.*X.*Z \ > > -eX.*Z.*Y \ > > -eX.*Y.*Z \ > > input*.txt > > > > > > Workaround #2 > > ============= > > I can pipe greps together. This is what I currently do. > > This is more convenient and feels faster than workaround #1, but > > I suspect the inter-process overhead is significant. > > > > If grep implemented this internally, it could zero-copy. > > Being able to "grep -rnH --and" &c would also be convenient. > > > > For example, > > > > grep --and -F -eX -eY -eZ input*.txt # becomes > > > > cat input*.txt | > > grep -F -eX | > > grep -F -eY | > > grep -F -eZ > Although I do not know wheter it is discussed and/or rejected, to add the function to grep, internal conversion as workaround #1 will be impremented in grep. However, it scales poorly as you say, and it will be slower than workaround #2 in many cases.
