Package: grep
Version: 3.3-1
Severity: wishlist
(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
