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- Version 2.0:
-
- The most important user visible change is that egrep and fgrep have
- disappeared as separate programs into the single grep program mandated
- by POSIX 1003.2. New options -G, -E, and -F have been added,
- selecting grep, egrep, and fgrep behavior respectively. For
- compatibility with historical practice, hard links named egrep and
- fgrep are also provided. See the manual page for details.
-
- In addition, the regular expression facilities described in Posix
- draft 11.2 are now supported, except for internationalization features
- related to locale-dependent collating sequence information.
-
- There is a new option, -L, which is like -l except it lists
- files which don't contain matches. The reason this option was
- added is because '-l -v' doesn't do what you expect.
-
- Performance has been improved; the amount of improvement is platform
- dependent, but (for example) grep 2.0 typically runs at least 30% faster
- than grep 1.6 on a DECstation using the MIPS compiler. Where possible,
- grep now uses mmap() for file input; on a Sun 4 running SunOS 4.1 this
- may cut system time by as much as half, for a total reduction in running
- time by nearly 50%. On machines that don't use mmap(), the buffering
- code has been rewritten to choose more favorable alignments and buffer
- sizes for read().
-
- Portability has been substantially cleaned up, and an automatic
- configure script is now provided.
-
- The internals have changed in ways too numerous to mention.
- People brave enough to reuse the DFA matcher in other programs
- will now have their bravery amply "rewarded", for the interface
- to that file has been completely changed. Some changes were
- necessary to track the evolution of the regex package, and since
- I was changing it anyway I decided to do a general cleanup.
-