On 11/15/2016 03:13 PM, Jim Meyering wrote:
We should retain the optimization when reading from stdin that is neither a pipe nor a tty.
I am toying with the idea of retaining the optimization only if lseek-to-EOF succeeds, a heuristic that is a bit more restrictive. This arguably would conform better to the POSIX requirement that when grep exits "the file offset in the open file description is properly positioned just past the last byte processed by the utility." See the INPUT FILES section of <http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap01.html#tag_17_04>.
