Versions of awk (Unix Power Tools, 3rd Edition)
20.11. Versions of awk
awk was introduced as part of
Unix's seventh edition and has been part of the
standard distribution ever since.
In 1985, the authors of awk extended the language,
adding many useful features. Unfortunately, this new version remained
inside AT&T for several years. It became a regular part of
AT&T's System V as of Release 3.1. It can be
found under the name of nawk (for
"new awk"); the
older version still exists under its original name.
Go to http://examples.oreilly.com/upt3 for more information on: gawk
Unfortunately, nawk is not available on all
systems. The good news is that the Free Software Foundation GNU
project's version of awk, called
gawk, implements all the features of the new
awk.
In general, you can assume that what is true for
nawk is true for gawk, unless
gawk is explicitly called out. Scripts written for
nawk are 100 percent compatible with
gawk. If you want to use one of the
nawk scripts and don't have
nawk on your system, simply change the script to
invoke gawk instead.
There are a few areas where gawk has introduced
gawk-specific features; however, recent versions
of nawk support many of these features, suggesting
that the remaining differences are really very minor. This
shouldn't matter in any case, since we do supply
gawk on the disc.
This book doesn't cover any of the
awks in detail. The recent
awks, especially, have quite a few features in
common -- so documentation for any one of them should help you
learn the others.
In this book, we show scripts for awk as well as
scripts that work only on nawk and
gawk. But we barely scratch the surface of all the
awks' features. The completely
revised second edition of O'Reilly &
Associates' sed & awk has
detailed information on all of them.[58] There's also lots of
documentation on the CD-ROM [see http://examples.oreilly.com/upt3]. Take your pick.
[58]And thanks to
Arnold Robbins, coauthor of the second edition, for his help with
this section and other awk material in this
book.
--JP and DD, TOR
20.10. Quick Reference: awk21. You Can't Quite Call This Editing
Copyright © 2003 O'Reilly & Associates. All rights reserved.
Wyszukiwarka
Podobne podstrony:
ch20ch20ch20 (8)ch20ch20ch20 (2)ch20 (3)ch20 (17)ch20 (16)CH20ch20Ch20 pg645 654ch20ch20ch20więcej podobnych podstron