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Subject: comp.lang.awk FAQ

This article was archived around: 24 Jun 2002 11:00:00 -0600

All FAQs in Directory: computer-lang/awk
All FAQs posted in: comp.lang.awk
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Archive-name: computer-lang/awk/faq Author: awkfaq@locutus.ofB.ORG (Russell Schulz) Comp-lang-awk-archive-name: faq Posting-Frequency: biweekly Last-modified: 2002-May-23 Posting-Via: news.demon.net (mail2news) Not-Posting-Via: my connectivity provider who doesn't do news for uucp now Not-Posting-Via-The-Cable-Modem-Because: I don't want to
Frequently Asked Questions == FAQ The FAQ list for comp.lang.awk can be found on the Internet: <ftp://rtfm.mit.edu/pub/usenet/comp.lang.awk/faq> <http://www.faqs.org/faqs/computer-lang/awk/faq/> A version reformatted for PalmPilot may be found at <http://www.castagnetto.org/download.php?fname=awkfaq.zip> An Italian translation may be found at <http://www.geocities.com/Eureka/Plaza/7153/i-awk-faq.html> [error 1999-Jul-20] ======================================================================== Contents: 1. Disclaimer 2. Spam 3. Can you answer my awk question? 4. How can I add a FAQ and its answer to the FAQ list? 5. What is awk? 6. What well-maintained awk-compatible languages are there? 6.1 nawk 6.2 gawk 6.3 mawk 6.4 tawk 6.5 mksawk 6.6 awkcc 6.7 awk2c 6.8 a2p 6.9 awka 7. Where can I buy awk? 7.1 AT&T (awk, awkcc) 7.2 Thompson Automation (tawk) 7.3 MKS (awk, can generate standalone interpreted .exe) 8. Where can I get awk for free? For what platforms? 8.0 meta-answer 8.1 the one true awk 8.2 gawk 8.2.1 gawk precompiled for MS-DOS or OS/2 8.2.2 gawk precompiled for Macintosh 8.2.3 gawk precompiled for Risc OS on Acorn 8.2.4 jgawk (Japanese gawk) 8.2.5 gawk.dll 8.3 mawk 8.4 awk2c 8.5 awka 8.6 awk in scheme 8.98 various old binary-only distributions for MSDOS 8.99 awkcc 9. Why would anyone still use awk instead of perl? 10. How can I learn awk? 11. What are some other awk resources? 12. How do I report a bug in gawk? 13. What's wrong with gawk on Digital's OSF/1? 14. How can I access shell or environment variables in an awk script? 14.1 Environment variables in general 14.2 Unix Shell Quoting 14.3 ENVIRON and "env"|getline 14.4 exporting environment variables back to the parent process 15. Is there an easy way to determine if you have oawk or nawk? 16. How does awk deal with multiple files? 16.0 Version warning 16.1 How can awk test for the existence of a file? 16.2 How can I get awk to read multiple files? 16.3 How can I tell from which file my input is coming? 16.4 How can I get awk to open multiple files (selected at runtime)? 16.5 How can I treat the first file specially? 16.6 How can I explicitly pass in a filename to treat specially? 17. How many elements were created by split()? 18. How can I split a string into characters? 19. Why does SunOS/Solaris awk behave oddly? 20. How do I have dynamic-width printf strings, like C? 21. Why doesn't "\\$" behave like /\\$/ ? Why don't parentheses match? 22. What is awk's exit code? 23. How can I get awk to be case-insensitive? 24. How can I force a numeric/non-numeric comparison? 25. Why does { FS=":"; print $1 } not split the first record? 26. Did ^ and $ and . change in gawk? 27. Why doesn't awk 'begin {...}' work? 28. Why does awk 'BEGIN { print 6 " " -22 }' lose the space? 29. How do I take advantage of gawk's networking support? 98. Miscellaneous 99. Credits ======================================================================== 1. Disclaimer Read at your own risk. The current, previous, or original authors make no claim as to fitness for any purpose or absence of any errors, and offer no warranty. Do not eat. ======================================================================== 2. Spam you wouldn't believe how much spam I get to this address. ======================================================================== 3. Can you answer my awk question? Probably not. Please don't mail it to me. Read the FAQ, and the materials pointed to by it, and if you can't find an answer there, by all means post to the newsgroup. If you need help posting, see <http://groups.google.com/> among others. A FAQ list is intended to reduce traffic on a newsgroup, not eliminate it. ======================================================================== 4. How can I add a FAQ and its answer to the FAQ list? Mail BOTH of them to me. Then I can add them to the FAQ and it should help people who have that same question later, as well as everyone who reads the group, because they won't see it asked and answered so often. I do not work on this FAQ every day, but I will try to get updates incorporated in a timely manner. Of course, don't mail me my entire FAQ! I already have a copy! There are copies available all over the web that I could use if I lost mine! I pay for my access; don't you? ======================================================================== 5. What is awk? awk is a programming language, named after its three original authors: Alfred V. Aho Brian W. Kernighan Peter J. Weinberger they write: `` Awk is a convenient and expressive programming language that can be applied to a wide variety of computing and data-manipulation tasks. '' the title of the book uses `AWK', but the contents of the book use `awk' (except at the beginning of sentences, as above). I will attempt to do the same (except perhaps at the beginning of sentences, as above). most implementations of awk are interpreters which read your awk source program and parse it and act on it directly. some vendors have developed awk compilers which will produce an `executable' that may be run stand-alone -- thus, the end user does not have access to the source code. there are also various awk->C converters which allow you to achieve the same functionality (by compiling the resulting C code later). one of the most popular compilers, from Thompson Automation, continues to be the subject of many positive posts in the group. [ I don't really want to start a reviews section, but it may be appropriate. I think it's of general interest, and a good thing for the FAQ, but I don't want to be given any grief by a negative review I didn't write just because I'm distributing it. if you have a review you'd like me to put a pointer to, please inform me -- I already have some pointers of this form listed. ] comp.lang.awk is not particularly about sed; for sed discussion, see the sed FAQ (and other documents) for answers to common questions and group recommendations: <http://www.dbnet.ece.ntua.gr/~george/sed/sedfaq.html> <http://www.wollery.demon.co.uk/sed_faq.txt> <http://www.student.northpark.edu/pemente/sed/index.htm> <http://www.student.northpark.edu/pemente/sed/sedfaq.html> <http://www.student.northpark.edu/pemente/sed/sed1line.txt> this all seems unrelated to AWK Engineering AG at <http://www.awk.ch/>. ======================================================================== 6. What well-maintained awk-compatible languages are there? 6.1 nawk AT&T's `new awk' -- probably nobody uses the `old awk' anymore. interpreter might NOT be well-maintained 6.2 gawk from the GNU project interpreter 6.3 mawk from Michael Brennan interpreter 6.4 tawk from Thompson Automation interpreter compiler MS-Windows DLL 6.5 mksawk interpreter compiler from Mortice Kern Systems (MKS) an old version of mksawk is shipped as `nawk' on Ultrix and OSF/1. 6.6 awkcc translator to C might NOT be well-maintained 6.7 Brian Kernighan's awkc++ translator to C++ experimental <http://cm.bell-labs.com/cm/cs/who/bwk/awkc++.ps> 6.8 awk2c translator to C uses GNU awk libraries extensively, and is subject to GPL might NOT be well-maintained 6.9 a2p translator to Perl comes with Perl didn't used to handle multiple concatenations: e.g., var="x" "y" "z" -> must be in pairs: e.g., var=( "x" "y" ) "z" didn't used to handle redirection: e.g., { print("data") > "filename" } -> no known workaround 6.10 awka translator to C (comes with library) based on mawk subject to GPL <http://awka.sourceforge.net/> ======================================================================== 7. Where can I buy awk? 7.1 AT&T (awk, awkcc) _The AWK Programming Language_ says: phone +1 201 522 6900 [is this number still valid?] and login as `guest'. <http://www.unipress.com/att/new/awk.html> <http://www.unipress.com/att/new/awkcc.html> these versions might NOT be well-maintained they might also have the old `99 fields' limitation 7.2 Thompson Automation (tawk) <http://www.tasoft.com/tawk.html> Thompson Automation Software 5616 SW Jefferson Portland, OR 97221 USA North America: 800-944-0139 Phone: +1 503 224 1639 Fax: +1 503 224 3230 7.3 MKS (awk, can generate standalone interpreted .exe) <http://www.mks.ca/solution/tk/> Mortice Kern Systems 185 Columbia Street W Waterloo, ON N2L 5Z5 Canada North America: 800-265-2797 Phone: +1 519 884 2251 Fax: +1 519 884 8861 ======================================================================== 8. Where can I get awk for free? For what platforms? 8.0 meta-answer Obtaining Awk and Perl <http://www.crossmyt.com/hc/htmlchek/awk-perl.html> 8.1 the one true awk <http://cm.bell-labs.com/who/bwk/> <http://plan9.bell-labs.com/who/bwk/> <ftp://netlib.bell-labs.com/netlib/research/awk.bundle.Z> [ appears to no longer be available via ftp 1997/Oct/23 ] This is the version of awk described in "The Awk Programming Language", by A. V. Aho, B. W. Kernighan, and P. J. Weinberger (Addison-Wesley, 1988, ISBN 0-201-07981-X). Changes, mostly bug fixes, are listed in FIXES. 8.1.1 the one true awk precompiled for Win32 is available from the locations in 8.1; MS-DOS and OS/2 executables are available in the GNUish collection: <http://www.simtel.net/simtel.net/> <ftp://ftp.simtel.net/pub/simtelnet/gnu/gnuish> 8.2 gawk NOTE: gawk 3.0.2 had a per-record memory leak which was fixed for gawk 3.0.3 . <ftp://ftp.gnu.org/gnu/gawk/> e.g., <ftp://ftp.gnu.org/gnu/gawk/gawk-3.1.0.tar.gz> 8.2.1 gawk precompiled for MS-DOS, Win32, or OS/2 The djgpp collection contains a 32-bit DOS gawk, along with many GNU utilities which may be useful with gawk (djgpp ports understand long filenames on Windows 95): <http://www.simtel.net/simtel.net/> <ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/> (look for gwk*.zip) 32-bit DOS (djgpp), Win32, and 16-bit OS/2 and DOS versions are part of the GNUish project: <http://www.simtel.net/simtel.net/> <ftp://ftp.simtel.net/pub/simtelnet/gnu/gnuish/> <http://wuarchive.wustl.edu/systems/msdos/gnuish/> [error 1998/Apr/16] <http://simtel.coast.net/SimTel/gnu/gnuish.html> [defunct] 32-bit OS/2, Win32, and DOS (emx) versions: <http://www.leo.org/pub/comp/os/os2/leo/gnu/script/gnuawk.zip> (DE) <ftp://ftp-os2.cdrom.com/pub/os2/lang/gnuawk.zip> (US) 32-bit Win32 version (cygwin) <http://www.cygwin.com/> (CygWin requires some `buy in' to the CygWin Way -- this may not affect you, or it may make your life much easier, or it may break some small things you currently do. In particular, I have been bitten by CRLF-vs-LF issues and no-drive-letters issues.) 8.2.2 gawk precompiled for Macintosh <ftp://ftp.funet.fi/pub/mac/programming/gawk.sit> <ftp://ezinfo.ethz.ch/mac/programming/gnu-awk-211.> [note trailing .] <ftp://ftp.uwtc.washington.edu/pub/Mac/Programming/> <ftp://ftp.eos.hokudai.ac.jp/pub/mac/util/Gawk/> <ftp://ftp.cs.tu-berlin.de/pub/mac/lang/MPW/> gawk 3.0.3 for Risc OS (versions >= 3.1) on Acorn Binary ported by J.Kortink, available from <http://www.inter.nl.net/users/J.Kortink/> Wimp front end available from <http://www.wraith.u-net.com/soft.html> gawk 3.0.4 for Risc OS on Acorn Binary (with extensions) ported by Gavin Wraith, available from <http://www.wraith.u-net.com/arc/Gawk304.arc > 8.2.4 jgawk (Japanese gawk) <ftp://ftp.eos.hokudai.ac.jp/pub/mac/util/jgawk/> <ftp://ftp.fu-berlin.de/mac/mirrors/info-mac/text/jgawk-215.hqx> 8.2.5 gawk.dll <http://www.walkerj.muc.de/> old Gawk 2.15.2 (from 1995) plus extensions + read/Write functions for INI files + read-only functions for DBF files this is a _16-bit_ DLL, unfortunately without thunks works with Win3.1x, plus Win9x _from 16-bit callers_ intermittent pointer problems with complex regexs 8.3 mawk NOTE: do not use mawk 1.3.2 (a one-character change yields 1.3.3) due to an obscure (and rarely-appearing) regex problem. <ftp://ftp.whidbey.net/pub/brennan/> e.g., <ftp://ftp.whidbey.net/pub/brennan/mawk1.3.3.tar.gz> 8.3.1 mawk 1.3.3 for Risc OS on Acorn Binary (with extensions) ported by Gavin Wraith, available from <http://www.wraith.u-net.com/arc/Mawk133.arc> 8.4 awk2c <ftp://sunsite.unc.edu/pub/Linux/utils/text/awk2c050.tgz> 8.5 awka <http://awka.sourceforge.net/> 8.6 awk in scheme <http://charles.lehalle.free.fr/tools.html> 8.98 various old binary-only distributions for MSDOS <ftp://ftp.sunsite.org.uk/Mirrors/simtel.coast.net/coast/msdos/awk/> <http://www.simtel.net/pub/msdos/txtutl/> 8.99 awkcc [unknown] previous versions of this FAQ mentioned a file on MKS' web site. Neil Mahoney spent some time examining it and discovered it is just a package BUILT with awkcc, not awkcc itself. eventually, this notice will be removed. some of Neil's explorations are interesting for those looking for the real awkcc: Get file copied to my Sun 4 file system (where I do most of my work) $ ls -l awkcc -rw-r--r-- 1 neilm 1827 May 20 11:20 README -rw-r--r-- 1 neilm 1378 May 20 11:20 awk.h -rwxr-xr-x 1 neilm 118 May 20 11:20 awkcc.sh -rw-r--r-- 1 neilm 824 May 20 11:20 dollars.h -rw-r--r-- 1 neilm 3858 May 20 11:20 ear.h -rw-r--r-- 1 neilm 993 May 20 11:20 hash.h -rw-r--r-- 1 neilm 1707 May 20 11:20 header.h -rw-r--r-- 1 neilm 103468 May 20 11:21 libAWK.a -rw-r--r-- 1 neilm 4136 May 20 11:20 specassign.h -rw-r--r-- 1 neilm 14467 May 20 11:20 unipen.c -rw-r--r-- 1 neilm 275 May 20 11:20 y.tab.h Looking good! $ awkcc.sh fix errors found by run $ awkcc.sh no awkcc executable... what is this ? -rwxr-xr-x 1 neilm 106496 May 20 11:21 uniparse $ head -20 README ############################################## To compile the UNIPEN 1.0 parser, run awkcc.sh ############################################## The following files are from the awkcc package, provided by Chris Ramming (jcr@research.att.com), Copyright (c) 1991 AT&T. All Rights Reserved awk.h awkcc.sh copyright dollars.h ear.h hash.h header.h libAWK.a specassign.h y.tab.h The file unipen.c is machine generated c code from the unipen.awk parser, using the awkcc package. Copyright (c) 1994 - I. Guyon, AT&T Bell Labs. # DISCLAIMER: # ======================================================================== 9. Why would anyone still use awk instead of perl? a valid question, since awk is a subset of perl (functionally, not necessarily syntactically); also, the authors of perl have usually known awk (and sed, and C, and a host of other Unix tools) very well, and still decided to move on. there are some things that perl has built-in support for that almost no version of awk can do without great difficulty (if at all); if you need to do these things, there may be no choice to make. for instance, no reasonable person would try to write a web server in awk instead of using perl or even C, if the actual socket programming has to be written in traditional awk. however, gawk 3.1.0's /inet and ftwalk's built-in networking primitives may remove this particular limitation. however, there are some things in awk's favor compared to perl: - awk is simpler (especially important if deciding which to learn first) - awk syntax is far more regular (another advantage for the beginner, even without considering syntax-highlighting editors) - you may already know awk well enough for the task at hand - you may have only awk installed - awk can be smaller, thus much quicker to execute for small programs - awk variables don't have `$' in front of them :-) - clear perl code is better than unclear awk code; but NOTHING comes close to unclear perl code Tom Christiansen wrote in Message-ID: <3766d75e@cs.colorado.edu> > Awk is a venerable, powerful, elegant, and simple tool that everyone > should know. Perl is a superset and child of awk, but has much more > power that comes at expense of sacrificing some of that simplicity. ======================================================================== 10. How can I learn awk? The commercial vendors of DOS versions (MKS and Thompson) each have their own well written books with examples. [available separately?] English Book: _The AWK Programming Language_, by Aho, Kernighan and Weinberger, who invented the language. Published by Addison-Wesley. Lots of good material in not a lot of space. A little out of date with regard to POSIX awk. ISBN 0-201-07981-X <http://cm.bell-labs.com/cm/cs/awkbook/> <http://cseng.aw.com/book/0,3828,020107981X,00.html> [ text looks mangled at the beginning ] English Book: Effective Awk Programming ISBN 0-596-00070-7 (third edition) <http://www.oreilly.com/catalog/awkprog3/> (includes link to DocBook source) <http://www.gnu.org/manual/gawk> Russell recommends buying the book instead of trying to print it all out, for three reasons: 1. it's probably cheaper than using your own toner and paper. 2. some money goes back to help further development, both to Arnold Robbins (only if you buy from ORA) and the Free Software Foundation (if you buy from either ORA or the FSF). 3. it helps convince publishers that we _like_ having full documentation available on-line (e.g., for searching), but will still pay for a compact, bound copy. information, including an errata list, is on the web site. older editions, historical interest only: _Effective AWK Programming_ by Arnold Robbins. Published by SSC (+1 206-FOR-UNIX, <http://www.ssc.com/>, <mailto:sales@ssc.com>). Also published by the FSF as "The GNU AWK User's Guide"; Texinfo source is included with the gawk distribution, so you can also print this yourself. A highly-praised reference card is also included. ISBN 1-57831-000-8 (second edition) <http://www.ssc.com/ssc/eap/> ISBN 0-916151-88-3 (first edition) English reference card: ISBN 1-56592-729-X <http://www.oreilly.com/catalog/sedawkrepr/> English Book: second edition: _Sed & Awk_, by Dale Dougherty & Arnold Robbins, published by O'Reilly and Associates. _sed & awk_ describes two text manipulation programs that are mainstays of the UNIX programmer's toolbox. This new edition covers the sed and awk programs as they are now mandated by the POSIX standard and includes discussion of the GNU versions of these programs. <http://www.ora.com/catalog/sed2/> <http://www.ora.com/catalog/covers/sedawk-t.gif> ISBN 1-56592-225-5 An errata for the second edition of Sed & Awk is at <http://www.cs.colostate.edu/~dzubera/sedawk2.txt> historical notes on the first edition: _Sed & Awk_, by Dale Dougherty, published by O'Reilly and Associates. A nice introduction to sed and awk, showing how they relate to each other. However, the first edition is `full of typos and out-and-out mistakes'. <http://www.ora.com/catalog/sed/> ISBN 0-937175-59-5 a `by no means complete' errata list is available. the author mentions `later printings of the book have many of the errors fixed.' <http://www.cs.colostate.edu/~dzubera/sedawk.txt> English Book: _Unix awk and sed programmer's interactive workbook_ ISBN 0-13-082675-8 <http://www.phptr.com/phptrinteractive/> <http://www.phptr.com/phptrinteractive/unix/> <http://cw.prenhall.com/patsis/> How can people publish Unix books that mix up ` and ' ?!?! (Example: "sed `s/://'" won't do what they seem to think it will.) And why create a frames-only Java-only Navigator/IE-centric gratuitously-incompatible website?! None of these things entice me to actually read the book in any depth. Deutsch Book: awk und sed Helmut Herold ISBN 3-89319-685-4 <http://www.addison-wesley.de/projector/projector.asp?page=bookdetails&isbn=3893196854> <http://www.addison-wesley.de/katalog/item.ppml?textexpr=awk&id=00018> Deutsch Book: Linux-Unix Profitools, by Helmut Herold. awk, sed, lex, yacc, und make <http://www.addison-wesley.de/projector/projector.asp?page=bookdetails&isbn=3827314488> <http://www.addison-wesley.de/katalog/item.ppml?textexpr=awk&id=00287> ISBN 3-8273-1448-8 English Book: _Mastering Regular Expressions_, by Jeffrey E.F. Friedl, published by O'Reilly and Associates. (the `Hip Owls Book') ``... you will learn how to use regular expressions to solve problems and get the most out of tools that provide them. Not only that, but much more: this book is about _mastering_ regular expressions.'' <http://www.ora.com/catalog/regex/> errata, additions, change log available at the author's home page <http://public.yahoo.com/~jfriedl/regex/> ISBN 1-56592-257-3 Deutsch Book: Friedl's _Mastering Regular Expressions_. <http://www.oreilly.de/catalog/regexger/index.html> Web Site: <http://www.cs.hmc.edu/qref/awk.html> Getting started with Awk Web Site: <http://www.uga.edu/~ucns/wsg/unix/awk/> Awk introduction Web Site: <http://www.mbnet.mb.ca/~natewild/awk/awk.html> [ no longer available 1997/Oct/28 ] Information about Tawk; Awk sample source code Ian Gordon's Introduction to Gawk from Linux Journal <http://www.ssc.com/lj/issue25/1156.html> Juergen Kahrs' Gawk 3.1 introduction from Linux Journal <http://www.ssc.com/lj/issue60/> Awk Introduction <http://www.softlab.ece.ntua.gr/facilities/documentation/unix/docs/awk.ps> <http://www.softlab.ece.ntua.gr/facilities/documentation/unix/docs/awk.txt> <ftp://www.brooks.af.mil/pub/unix/white_papers/awk.ps> [error 2001/Apr/07] Awk introduction (PostScript and text) by awk authors (somewhat old, doesn't cover the many recent extensions, but still a valid introduction to the language) Web Site: <http://www.shelldorado.com/articles/awkcompat.html> Awk compatibility Web Site: <http://www.canberra.edu.au/~sam/whp/awk-guide.html> How to get things done in Awk Web Site: <http://www.novia.net/~phridge/programming/awk/> Awk Programming examples Japanese Book: _Tanoshii UNIX -UNIX he no shoutai-_, by Aya Sakamoto (UNIX is fun -an invitation to UNIX-) ASCII October 1990 <http://www.ascii.co.jp/> ISBN 4-7561-0785-0 A step by step UNIX tutorial for novices. Long chapter about awk, which follows chapters about grep and sed, gives good advice on general expressions and how awk is used in practice. Japanese Book: _Grep,Sed,Awk_ by Akihiro Miyoshi ISBN 4-87966-794-3 June 1998 264 pages Shuwa System Manual & Reference Series <http://www.shuwasystem.co.jp/books/wwwsrch/cgi-bin/content/794/index.htm> Serves both as a tutorial and a manual. Divided quite evenly into three parts. Regular expressions explored in detail in grep section. Japanese Book: _Awk wo 256 bai tsukau tame no hon_ by Shimura, Washikita and Nishimura ASCII August 1993 277 pages ISBN 4-75610-162-3 Manic book titled 'The Book to Use Awk 256 Times More'. Good illustrations and interesting insights. Lists '100 liners': a game, fortune telling etc. English Booklet: TCP/IP Internetworking With Gawk ISBN 1-882114-93-0 <http://home.vr-web.de/Juergen.Kahrs/gawk/gawkinet.html> An abridged form is included in O'Reilly's Effective Awk Programming 3e Hard copy also available as book on demand from <http://www.lob.de> ======================================================================== 11. What are some other awk resources? Alta Vista awk Related Searches (inconspicuously placed under the search edit box, given to graphical browsers only) <http://www.altavista.com/cgi-bin/query?pg=q&kl=XX&q=awk> Awk collections in various search engines <http://dir.yahoo.com/Computers_and_Internet/Programming_Languages/awk/> <http://dir.altavista.com/Computers/Programming/Languages/Awk.shtml> <http://www.dmoz.org/Computers/Programming/Languages/Awk/> Arnold Robbins' collection <ftp://ftp.freefriends.org/arnold/Awkstuff/> > A collection of awk related stuff that I'm starting and willing > to maintain. Currently includes Henry Spencer's awf and aaa > programs, Brian Kernighan's chem, and Nelson Beebe's awkpretty, > and some smaller items. Awk quick reference (in plain ASCII and PalmPilot format) <http://www.castagnetto.org/download.php?fname=awkqref.zip> Unix and awk courseware <http://www.cit.ac.nz/smac/unix/default.htm> Awk course <http://www.ee.ic.ac.uk/course/advanced/awk/awk.html> [error 2001/Apr/07] Developer information on awk <http://www.devinfo.com/languages/awk/> Spatial Analysis with Awk (course) <http://www.udel.edu/johnmack/frec682/682awk.html> Debugger and Assertion Checker for Awk <http://www.irisa.fr/EXTERNE/manifestations/AADEBUG95/Abstracts/auguston2.html> [error 2001/Apr/07] Free Compilers and Interpreters List <http://www.idiom.com/free-compilers/LANG/awk-1.html> Voicenet.com awk page <http://www.voicenet.com/tech/comp/prog/awk/> [error 2001/Apr/07] Four awk implementations for MS-DOS: How do they compare? <http://www.voicenet.com/tech/comp/prog/awk/awk2.rev> [error 2001/Apr/07] Gawk 3 manual <http://sunsite.ualberta.ca/Documentation/Info/by-chapter/gawk-3.0.3/> <ftp://sunsite.ualberta.ca/pub/Mirror/gnu/gawk/> Unix Vault <http://www2.shore.net/~jblaine/vault/> [error 2001/Apr/07] Yahoo's awk links <http://www.yahoo.com/Computers_and_Internet/Programming_Languages/Awk/> New Mexico Tech awk information <http://www.nmt.edu/tcc/help/lang/awk.html> <http://www.nmt.edu/bin/man?awk> [empty 1998/Apr/16] <http://www.nmt.edu/bin/man?gawk> A Supplemental Document For AWK - or - Things Al, Pete, And Brian Didn't Mention Much <http://oak.oakland.edu/pub/unix-c/info/awk-supplement.txt> [error 2001/Apr/07] [ interesting historically -- I always wondered exactly why I mistrusted setting `$n' and expecting `$0' to change -- and this document explains why. (it has since become standard behavior.) ] A* - an awk extension (paper by D.A.Ladd and J.C.Ramming) <http://sunsite.ust.hk/dblp/db/journals/tse/tse21.html> [error 2001/Apr/07] <http://www.usenix.org/~jcr/> [error 1998/Apr/16] [ does anyone know what issue of _Unix Review_ mentioned it? ] Konrad Hambrick's `rawketry' and AltAcc data reduction scripts <ftp://ftp.netcom.com/pub/ko/konrad/rawketry/> <ftp://ftp.netcom.com/pub/ko/konrad/altacc/software/> Ralph Becket's CGI and HTML Awk libraries <http://www.cam.sri.com/people/becket/awk/awk.html> [error 2001/Apr/07] E. Stiltner's creation of HTML tables with awk <http://www.sni.net/sccs/sccsadoc.htm> [error 2001/Apr/07] ftwalk / hawk > a language that attempts to scale awk principles up to > a level competitive with Perl, Python, etc. Run as ftwalk, > it does a file tree walk (think of find+awk). Run as hawk, > it runs awk scripts (not quite compatibly). <http://www.tomhull.com/ocston/projects/hawk.html> <http://ftwalk.sourceforge.net/> Data Junction Content Extraction Language (DJ CXL) similar to awk <http://www.datajunction.com/products/djxl.html> English Book Language and Computers ISBN 0-7486-0785-4 (paperback) ISBN 0-7486-0848-6 (hardcover) New Scientist #2071, 1997/Mar/01, p45; paragraph titled `Dream in awk' <http://www.ling.lancs.ac.uk/staff/andrew/etel.htm> <http://www.ling.lancs.ac.uk/staff/andrew/pubs.htm> <http://www.eup.ed.ac.uk/> <http://www.eup.ed.ac.uk/cgi/odbic.exe?input=NewWeb/Books/Barnbrook9856.htm> [ Blackwell's in Oxford has 3 copies under General Linguistics ] a book about computer-aided linguistics which uses awk as its implementation language English Lecture Notes; Combining sh, sed, and awk for language analysis <ftp://ftp.u-aizu.ac.jp/u-aizu/doc/Tech-Report/1997/97-2-007.ps.gz> <ftp://ftp.u-aizu.ac.jp/u-aizu/doc/Tech-Report/1997/97-2-007.tar.gz> Consultix: Awk Lecture / Lab courses (instructor-led) <http://www.consultix-inc.com/> How to get started with AWK <http://www.bolthole.com/AWK.html> awk resources for the Acorn RISC OS <http://www.awk.riscos.org.uk/> Troy A. Tiritilli's Awk Overview <http://www.students.stedwards.edu/~ttiriti/pl.htm (email me; stedwards.edu mail setup is broken) Henry Spencer's awf (Amazingly Workable Formatter) <http://www.simtel.net/simtel.net/> <ftp://ftp.zoo.toronto.edu/> (more precise URL eventually...) Jon-Egil Korsvold's awk archive <http://www.kortext.no/awk.htm> (English) <http://www.kortext.no/awkno.htm> (Norwegian) ======================================================================== 12. How do I report a bug in gawk? This is described in great detail in the gawk documentation. In brief: 1. Make sure what you've discovered is really a bug by checking the documentation and, if possible, comparing with nawk and mawk. 2. Cut down the program and data to as small as possible a test case that will illustrate the bug. 3. Optionally post to comp.lang.awk; this allows others to confirm or deny the behavior, and its incorrectness (or lack thereof). 4. Send mail to <mailto:bug-gawk@gnu.org>. This automatically sends a copy to Arnold Robbins. Do not JUST post in comp.lang.awk; Arnold's readership there is sporadic, and of course any Usenet article can be missed, killed, or dropped. ======================================================================== 13. What's wrong with gawk on Digital's OSF/1? The version of gawk shipped with OSF/1 is very old, based on gawk 2.14. Get the current version from a GNU mirror near you, and if you still have a problem, report it as per the directions in the gawk documentation. ======================================================================== 14. How can I access shell or environment variables in an awk script? 14.0 shells the examples using quoting are intended for use with any standard (sh-compatible-quoting) Unix shell. as with all complex quoting, all these examples become much easier to work with (or under DOS and MS-Windows, less impossible) when put in a file and invoked with `awk -f filename.awk' instead. non-sh-compatible shells will require different quoting. if you're not even using Unix (or a ported Unix shell), just ignore the whole section on quoting. 14.1 Environment variables in general Answer 1: on Unix, use "alternate quoting", e.g. awk -F: '$1 ~ /'"$USER"'/ {print $5}' /etc/passwd ^^^^^^^^*******^^^^^^^^^^^^^^ any standard Unix shell will send the underlined part as one long argument (with embedded spaces) to awk, for instance: $1 ~ /bwk/ {print $5} Note that there may not be any spaces between the quoted parts. Otherwise, you wouldn't end up a single, long script argument, because Unix shells break arguments on spaces (unless they are `escaped' with `\', or in '' or "", as the above example shows). Answer 2: RTFM to see if and how your awk supports variable definitions on the command line, e.g., awk -F: -v name="$USER" '$1 ~ name {print $5}' /etc/passwd Answer 3: RTFM if your awk can access enviroment vars. Then perhaps awk -F: '$1 ~ ENVIRON["USER"] {print $5}' /etc/passwd Always remember for your /bin/sh scripts that it's easy to put things into the environment for a single command run: name=felix age=56 awk '... ENVIRON["name"] .....' this also works with ksh and some other shells. The first approach is extremely portable, but doesn't work with awk "-f" script files. In that case, it's better to use a shell script and stretch a long awk command argument in '...' across multiple lines if need be. Also note: /bin/csh requires a \ before an embedded newline, /bin/sh not. 14.2 Unix Shell Quoting Quoting can be such a headache for the novice, in shell programming, and especially in awk. Art Povelones posted a long tutorial on shell quoting on 1999/09/30 which is probably too much detail to repeat with the FAQ; if you could use it, search via <http://groups.google.com/>. Tim Maher offered his <http://www.consultix-inc.com/quoting.txt>. This approach is probably the best, and easiest to understand and maintain, for most purposes: (the '@@' is quoted to ensure the shell will copy verbatim, not interpreting environment variable substitutions etc.) cat <<'@@' > /tmp/never$$.awk { print "Never say can't." } @@ awk -f /tmp/never$$.awk; rm /tmp/never$$.awk If you enjoy testing your shell's quoting behavior frequently, you could try these: (see below for a verbose explanation of the first one, with 7 quotes) awk 'BEGIN { q="'"'"'";print "Never say can"q"t."; exit }' nawk -v q="'" 'BEGIN { print "Never say can"q"t."; exit }' awk 'BEGIN { q=sprintf("%c",39); print "Never say can"q"t."; exit }' awk 'BEGIN { q=sprintf("%c",39); print "Never say \"can"q"t.\""; exit }' However, you would also have to know why you could not use this: awk 'BEGIN { q="\'"; print "Never say \"can"q"t.\""; exit }' explanation of the 7-quote example: note that it is quoted three different ways: awk 'BEGIN { q="' "'" '";print "Never say can"q"t."; exit }' and that argument comes out as the single string (with embedded spaces) BEGIN { q="'";print "Never say can"q"t."; exit } which is the same as BEGIN { q="'"; print "Never say can" q "t."; exit } ^^^^^^^^^^^^^ ^ ^^ | | | || | | | || vvvvvvvvvvvvv | || Never say can v || ' vv t. which, quite possibly with too much effort to be worth it, gets you Never say can't. 14.3 ENVIRON[] and "env"|getline Modern versions of new awk (gawk, mawk, Bell Labs awk, any POSIX awk) all provide an array named ENVIRON. The array is indexed by environment variable name; the value is that variable's value. For instance, ENVIRON["HOME"] might be "/home/chris". To print out all the names and values, use a simple loop: for (i in ENVIRON) printf("ENVIRON['%s'] = '%s'\n", i, ENVIRON[i]) What if my awk doesn't have ENVIRON[]? Short answer, get a better awk. There are many freely available versions. Longer answer, on Unix you can use a pipe from the `env' or `printenv' commands, but this is less pretty, and may be a problem if the values contain newlines: # test this on your system before you depend on it! while ( ("env" | getline line) >0 ) { varname=line varvalue=line sub(/=.*$/,"",varname) sub(/^[^=]*=/,"",varvalue) print "var [" varname "]='" varvalue "'" } 14.4 exporting environment variables back to the parent process How can I put values into the environment of the program that called my awk program? Short answer, you can't. Unix ain't Plan 9, and you can't tweak the parent's address space. (DOS isn't even Unix, so it lets any program overwrite any memory location, including the parent's environment space. But the details are [obviously] going to be fairly icky. Avoid.) Longer answer, write the results in a form the shell can parse to a temporary file, and have the shell "source" the file after running the awk program: awk 'BEGIN { printf("NEWVAR='%s'\n", somevalue) }' > /tmp/awk.$$ . /tmp/awk.$$ # sh/ksh/bash/pdksh/zsh etc rm /tmp/awk.$$ With many shells, you can use `eval', but this is also cumbersome: eval `awk 'BEGIN { print "NEWVAR=" somevalue }'` Csh syntax and more robust use of quotation marks are left as exercises for the reader. ======================================================================== 15. Is there an easy way to determine if you have oawk or nawk? The following in a BEGIN rule will do the trick. if (ARGC == 0) # old awk else # new awk ======================================================================== 16. How does awk deal with multiple files? 16.0 Version warning some of these techniques will require non-ancient versions of awk. 16.1 How can awk test for the existence of a file? the most portable way is to simply try and read from the file. function exists(file, dummy, ret) { ret=0; if ( (getline dummy < file) >=0 ) { # file exists (possibly empty) and can be read ret = 1; close(file); } return ret; } [ I've read reports that earlier versions of mawk would write to stderr as well as getline returning <0 -- is this still true? ] on Unix, you can probably use the `test' utility if (system("test -r " file) == 0) # file is readable else # file is not readable 16.2 How can I get awk to read multiple files? it's automatic (under Unix at least) -- use something like: awk '/^#include/ {print $2}' *.c *.h 16.3 How can I tell from which file my input is coming? use the built-in variable FILENAME: awk '/^#include/ {print FILENAME,$2}' *.c *.h 16.4 How can I get awk to open multiple files (selected at runtime)? use `getline', `close', and `print EXPR > FILENAME', like: # assumes input file has at least 1 line, output file writeable function double(infilename,outfilename, aline) { while ( (getline aline < infilename) >0 ) print(aline aline) > outfilename; close(infilename); close(outilename); } 16.5 How can I treat the first file specially? use FILENAME, thusly: BEGIN { rulesfile="" } rulesfile == "" { rulesfile = FILENAME; } FILENAME == rulesfile { build_rule($0); } FILENAME != rulesfile { apply_rule($0); } Example: Suppose you have a text-line "database" and you want to make some batch changes to it, by replacing some old lines with new lines. BEGIN { rulesfile="" } rulesfile == "" { rulesfile = FILENAME; } rulesfile == FILENAME { replace[$1] = $0; } rulesfile != FILENAME \ { if ($1 in replace) print replace[$1]; else print; } another way, using ARGV: (FILENAME == ARGV[1]) { replace[$1] = $0; next } ($1 in replace) { print replace[$1]; next } { print } 16.6 How can I explicitly pass in a filename to treat specially? use `-v rulesfile=filename' like you would any other variable, and then use a `getline' loop (and `close') in your BEGIN statement. BEGIN \ { if (rulesfile=="") { print "must use -v rulesfile=filename"; exit(1); } while ( (getline < rulesfile) >0 ) replace[$1]=$0; close(rulesfile); } { if ($1 in replace) print replace[$1]; else print; } ======================================================================== 17. How many elements were created by split()? when I do a split on a field, e.g., split($1,x,"string") how can i find out how many elements x has (I mean other than testing for null string or doing a `for (n in x)' test)? split() is a function; use its return value: n = split($1, x, "string") ======================================================================== 18. How can I split a string into characters? in portable POSIX awk, the only way to do this is to use substr to pull out each character, one by one. this is painful. however, gawk, mawk, and the newest version of the Bell Labs awk all allow you to set FS = "" and use "" as the third argument of split. so, split("chars",anarray,"") results in the array anarray containing 5 elements -- "c", "h", "a", "r", "s". if you don't have any ^As in your string, you could try: string=$0; gsub(".", "&\001", string) n=split(string, anarray, "\001") for (i=1;i<=n;i++) print "character " i "is '" anarray[i] "'"; ======================================================================== 19. Why does SunOS/Solaris awk behave oddly? I want to use the tolower() function with SunOS nawk, but all I get is nawk: calling undefined function tolower The SunOS nawk is from a time before awk acquired the tolower() and toupper() functions. Either use one of the freely available awks, or or use /usr/xpg4/bin/awk (if you have it), or write your own function to do it using index, substr, and gsub. An example of such a function is in O'Reilly's _Sed & Awk_. Patrick TJ McPhee writes: > SunOS includes three versions of awk. /usr/bin/awk is the old > (pre-1989) version. /usr/bin/nawk is the new awk which appeared > in 1989, and /usr/xpg4/bin/awk is supposed to conform to the single > unix specification. No one knows why Sun continues to ship old awk. ======================================================================== 20. How do I have dynamic-width printf strings, like C? with modern awks, you can just do it like you would in C (though the justification is less clear; C doesn't have the trivial in-line string concatenation that awk does), like so: maxlen=0 for (i in arr) if (maxlen<length(arr[i])) maxlen=length(arr[i]) for (i in arr) printf("%-*s %s\n",maxlen,arr[i],i) with old awks, just do it like you would do if you didn't know about %* (this would be much more painful to do in C), like so: maxlen=0 for (i in arr) if (maxlen<length(arr[i])) maxlen=length(arr[i]) printfstring="%-" maxlen "s %s\n"; for (i in arr) printf(printfstring,arr[i],i) ======================================================================== 21. Why doesn't "\\$" behave like /\\$/ ? Why don't parentheses match? because "\\$" is a string and /\\$/ is not; in strings, some of the escape characters get eaten up (like \" to escape a double-quote within the string). /\\$/ => regular expression: literal backslash at end-of-expression "\\$" => string: \$ => regular expression: literal dollar sign to get behavior like the first case in a string, use "\\\\$" . there are other, less obvious characters which need the same attention; under-quoting or over-quoting should be avoided: parentheses are special for alternation: /\(test\)/ => 6 characters `(test)' "\(test\)" => /(test)/ => 4 characters `test' (with unused grouping) an example of trying to match some diagonal compass directions: /(N|S)(E|W)/ => `NE' or `NW' or `SE' or `SW' (correct) "(N|S)(E|W)" => /(N|S)(E|W)/ (correct) "\(N|S\)\(E|W\)" => /(N|S)(E|W)/ (correct) (NOTE: all \ had no effect) "\(N\|S\)\(E\|W\)" => /(N|S)(E|W)/ (correct) (NOTE: all \ had no effect) expressions that look similar but behave totally differently: /\(N|S\)\(E|W\)/ => `(N' or `S)(E' or `W)' /\(N\|S\)\(E\|W\)/ => `(N|S)(E|W)' only There is also confusion regarding different forms of special characters; POSIX requires that `\052' be treated as any other `*', even though it is written with 4 bytes instead of 1. In compatibility mode, gawk will treat it as though it were escaped , namely `\*'. ======================================================================== 22. What is awk's exit code? normally, the `exit' command exits with a value of zero. you can supply an optional numeric value to the `exit' command to make it exit with a value: if (whatever) exit 12; if you have an END block, control first transfers there. within the END block, an `exit' command exits immediately; if you had previously supplied a value, that value is used. but, if you give a new value to `exit' within the END block, the new value is used. this is documented in the GNU Awk User's Guide (gawk.texi). if you have an END block you want to be able to skip sometimes, you may have to do something like this: BEGIN \ { exitcode=0; ... } # normal rules processing... { ... if (fatal) { exitcode=12; exit(exitcode); } ... } END { if (exitcode!=0) exit(exitcode); ... } ======================================================================== 23. How can I get awk to be case-insensitive? 23.1. use tolower() - portable - must be explicitly used for each comparison instead of: if (avar=="a" || avar=="A") { ... } use: if (tolower(avar)=="a") { ... } or at the beginning of your code, add a line like { for (i=0;i<=NF;i++) $i=tolower($i) } { $0=tolower($0); } # modern awks will rebuild $1..$NF also 23.2. use IGNORECASE=1; - gawk only - used for all comparisons, regex comparisons, index() function - not used for array indexing ======================================================================== 24. How can I force a numeric/non-numeric comparison? these are the canonical, work-in-all-versions snippets. there are many others, most longer, some shorter (but possibly less portable). to compare two variables as numbers ONLY, use if (0+var1 == 0+var2) to compare two variables as non-numeric strings ONLY, use if ("" var1 == "" var2) ======================================================================== 25. Why does { FS=":"; print $1 } not split the first record? basically, you should set FS before it may be called upon to split $0 into fields. once awk encounters a `{', it is probably too late. some awk implementations set the fields at the beginning of the block, and don't re-parse just because you changed FS. to get the desired behavior, you must set FS _before_ reading in a line. e.g., BEGIN { FS=":" } { print $1 } e.g., awk -F: '{ print $1 }' if you run code like this { FS=":"; print $1 } on this data: first:second:third but not last:fourth First:Second:Third But Not Last:Fourth FIRST:SECOND:THIRD BUT NOT LAST:FOURTH you may get either this: or this: ---- ------- first first:second:third First First FIRST FIRST perhaps more surprisingly, code like { FS=":"; } { print $1; } will also behave in the same way. ======================================================================== 26. Did ^ and $ and . change in gawk? yes. early versions cared about \n (newlines) and treated them specially. version 3.* and later are more POSIX-compliant here. ======================================================================== 27. Why doesn't awk 'begin {...}' work? it needs to be `BEGIN' (i.e., it's case-sensitive). ======================================================================== 28. Why does awk 'BEGIN { print 6 " " -22 }' lose the space? You'd expect `6 -22', but you get `6-22'. It's because the `" " -22' is grouped first, as a substraction instead of a concatenation, resulting in the numeric value `-22'; then it is concatenated with `6', giving the string `6-22'. Gentle application of parentheses will avoid this. ======================================================================== 29. How do I take advantage of gawk's networking support? (I expect this will become removed from the FAQ as people become more aware of the new gawk documentation covering this. But it's new and cool and deserves attention.) Network interfacing in gawk is easier than in many other languages. Networking connections are made available like files in gawk. You can open, read, write and close them. This script opens a connection to the machine you are working on (localhost). Then it reads the answer and closes the connection. BEGIN \ { NetService = "/inet/tcp/0/localhost/finger"; print "name" |& NetService; while ((NetService |& getline) > 0) print $0; close(NetService); } It tells you which users are currently logged into your system. Note the similarity to ordinary file reading. With gawk 3.1.0, this networking support can not be used on Microsoft Windows unless you are using the Cygwin environment. If you have Cygwin installed, configure and compile gawk as if you were using a Unix system: tar -xvpzf gawk-3.1.x.tar.gz # x is patch number cd gawk-3.1.x ./configure && make The configure step takes a llloooonnngggg time. ======================================================================== 98. Miscellaneous ======================================================================== 99. Credits I expect most of the information in this FAQ to be supplied by people other than myself -- it's just going to work better that way. The newsgroup readers have a LOT more awk experience than I ever will (unless I multiply myself by a few thousand, which is not legal with today's tax laws). These people have contributed to the well-being of the FAQ: arnold [at] skeeve.com (Arnold D. Robbins) walkerj [at] compuserve.com (James G. Walker) jland [at] worldnet.att.net (Jim Land) yuli.barcohen [at] telrad.co.il (Yuli Barcohen) johnd [at] mozart.inet.co.th (John DeHaven) amnonc [at] mercury.co.il (Amnon Cohen) saguyami [at] post.tau.ac.il (Shay) hankedr [at] mail.auburn.edu (Darrel Hankerson) mark [at] ispc001.demon.co.uk (Mark Katz) brennan [at] whidbey.com (Michael D. Brennan) neitzel [at] gaertner.de (Martin Neitzel) pjf [at] osiris.cs.uoguelph.ca (Peter Jaspers-Fayer) dmckeon [at] swcp.com (Denis McKeon) neil_mahoney [at] il.us.swissbank.com (Neil Mahoney) dzubera [at] CS.ColoState.EDU (Zube) allen [at] gateway.grumman.com (John L. Allen) jerabek [at] rm6208.gud.siemens.co.at (Martin Jerabek) thull [at] ocston.org (Tom Hull) bmarcum [at] iglou.com (Bill Marcum) thobe [at] lafn.org (Glenn Thobe) boffi [at] rachele.stru.polimi.it (giacomo boffi) hastinga [at] tarim.dialogic.com (Austin Hastings) konrad [at] netcom.com (Konrad Hambrick) jmccann [at] WOLFENET.com (James McCann) eia018 [at] comp.lancs.ac.uk (Dr Andrew Wilson) Alex.Schoenmakers [at] lhs.be rwab1 [at] cl.cam.ac.uk (Ralph Becket) jesusmc [at] scripps.edu (Jesus M. Castagnetto) monty [at] primenet.com (Jim Monty) epement [at] ripco.com (Eric Pement) gavin [at] wraith.u-net.com (Gavin Wraith) pierre [at] mail.asianet.it (Gianni Rondinini) lothar [at] u-aizu.ac.jp (Lothar M. Schmitt) morrisl [at] scn.org (Larry D. Morris) Juergen.Kahrs [at] t-online.de kahrs [at] iSenseIt.de (Juergen Kahrs) tim [at] consultix-inc.com (Tim Maher/CONSULTIX) phil [at] bolthole.com (Philip Brown) andrew_sumner [at] bigfoot.com (Andrew Sumner) jblaine [at] shore.net (Jeff Blaine) dmeier.esperanto [at] gmx.de (Detlef Meier) heiner.steven [at] nexgo.de (Heiner Steven) joe [at] plaguesplace.dyndns.org hstein [at] airmail.net (Harry Stein) ptjm [at] interlog.com (Patrick TJ McPhee) db21 [at] ih4ess.ih.lucent.com (David Beyerl) art [at] pove.com (Art Povelones) jari.aalto [at] ntc.nokia.com (Jari Aalto) jlaiho [at] ichaos.nullnet.fi (Juha Laiho) walter [at] wbriscoe.demon.co.uk (Walter Briscoe) SimonN [at] draeger.com (Nicole Simon) peter.tillier [at] btinternet.com (Peter S Tillier) churchyh [at] ccwf.cc.utexas.edu (Henry Churchyard) Ferran.Jorba [at] uab.es (Ferran Jorba) Kalle.Tuulos [at] nmp.nokia.com (Kalle Tuulos) rms [at] friko.onet.pl (Rafal Sulejman) pjfarley [at] banet.net (Peter J. Farley III) neel [at] gnu.org afu [at] wta.att.ne.jp pez68 [at] netscape.net (Peter Stromberg) edgar.j.ramirez [at] lmco.com (Edgar J. Ramirez) pholzleitner [at] unido.org (Peter HOLZLEITNER) bps03z [at] email.mot.com (Peter Saffrey) jidanni [at] kimo.com.tw (Dan Jacobson) lehalle [at] earthling.net (Charles-Albert Lehalle) robin.moffatt [at] ntlworld.com (Robin Moffatt) markus [at] biewer.com (Markus B. Biewer) vincent [at] delau.nl (Vincent de Lau) vjpnreddy [at] hotmail.com (Jaya Reddy) David.Billinghurst [at] riotinto.com (David Billinghurst) j-korsv [at] online.no (Jon-Egil Korsvold) Thanks. ======================================================================== thus endeth the awk FAQ.