GAWK: Effective AWK Programming

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278 GAWK: Effective AWK ProgrammingIn order to use gawk, you need to have a shell, either text or graphics, that does not mapall the characters of a command line to uppercase. Maintaining case distinction in optionflags is very important (see Section 11.2 [Command-Line Options], page 177). These daysthis is the default and it may only be a problem for some very old machines. If your systemdoes not preserve the case of option flags, you need to upgrade your tools. Support for I/Oredirection is necessary to make it easy to import awk programs from other environments.Pipes are nice to have but not vital.B.4.1.1 Compiling gawk on the Atari STA proper compilation of gawk sources when sizeof(int) differs from sizeof(void *)requires an ISO C compiler. An initial port was done with gcc. You may actually preferexecutables where ints are four bytes wide but the other variant works as well.You may need quite a bit of memory when trying to recompile the gawk sources, as somesource files (‘regex.c’ in particular) are quite big. If you run out of memory compiling sucha file, try reducing the optimization level for this particular file, which may help.With a reasonable shell (bash will do), you have a pretty good chance that the configureutility will succeed, and in particular if you run GNU/Linux, MiNT or a similar operatingsystem. Otherwise sample versions of ‘config.h’ and ‘Makefile.st’ are given in the ‘atari’subdirectory and can be edited and copied to the corresponding files in the main sourcedirectory. Even if configure produces something, it might be advisable to compare itsresults with the sample versions and possibly make adjustments.Some gawk source code fragments depend on a preprocessor define ‘atarist’. Thisbasically assumes the TOS environment with gcc. Modify these sections as appropriate ifthey are not right for your environment. Also see the remarks about AWKPATH and envsepin Section B.4.1.2 [Running gawk on the Atari ST], page 278.As shipped, the sample ‘config.h’ claims that the system function is missing from thelibraries, which is not true, and an alternative implementation of this function is providedin ‘unsupported/atari/system.c’. Depending upon your particular combination of shelland operating system, you might want to change the file to indicate that system is available.B.4.1.2 Running gawk on the Atari STAn executable version of gawk should be placed, as usual, anywhere in your PATH whereyour shell can find it.While executing, the Atari version of gawk creates a number of temporary files. Whenusing gcc libraries for TOS, gawk looks for either of the environment variables, TEMP orTMPDIR, in that order. If either one is found, its value is assumed to be a directory fortemporary files. This directory must exist, and if you can spare the memory, it is a goodidea to put it on a RAM drive. If neither TEMP nor TMPDIR are found, then gawk uses thecurrent directory for its temporary files.The ST version of gawk searches for its program files, as described in Section 11.4 [TheAWKPATH Environment Variable], page 183. The default value for the AWKPATH variable istaken from DEFPATH defined in ‘Makefile’. The sample gcc/TOS ‘Makefile’ for the ST inthe distribution sets DEFPATH to ".,c:\lib\awk,c:\gnu\lib\awk". The search path canbe modified by explicitly setting AWKPATH to whatever you want. Note that colons cannotbe used on the ST to separate elements in the AWKPATH variable, since they have another
Appendix B: Installing gawk 279reserved meaning. Instead, you must use a comma to separate elements in the path. Whenrecompiling, the separating character can be modified by initializing the envsep variable in‘unsupported/atari/gawkmisc.atr’ to another value.Although awk allows great flexibility in doing I/O redirections from within a program,this facility should be used with care on the ST running under TOS. In some circumstances,the OS routines for file-handle pool processing lose track of certain events, causing thecomputer to crash and requiring a reboot. Often a warm reboot is sufficient. Fortunately,this happens infrequently and in rather esoteric situations. In particular, avoid having onepart of an awk program using print statements explicitly redirected to ‘/dev/stdout’, whileother print statements use the default standard output, and a calling shell has redirectedstandard output to a file.When gawk is compiled with the ST version of gcc and its usual libraries, it acceptsboth ‘/’ and ‘\’ as path separators. While this is convenient, it should be remembered thatthis removes one technically valid character (‘/’) from your file name. It may also createproblems for external programs called via the system function, which may not support thisconvention. Whenever it is possible that a file created by gawk will be used by some otherprogram, use only backslashes. Also remember that in awk, backslashes in strings have tobe doubled in order to get literal backslashes (see Section 2.2 [Escape Sequences], page 25).B.4.2 Installing gawk on BeOSSince BeOS DR9, all the tools that you should need to build gawk are included with BeOS.The process is basically identical to the Unix process of running configure and then make.Full instructions are given below.You can compile gawk under BeOS by extracting the standard sources and runningconfigure. You must specify the location prefix for the installation directory. For BeOSDR9 and beyond, the best directory to use is ‘/boot/home/config’, so the configurecommand is:configure --prefix=/boot/home/configThis installs the compiled application into ‘/boot/home/config/bin’, which is alreadyspecified in the standard PATH.Once the configuration process is completed, you can run make, and then ‘make install’:$ make...$ make installBeOS uses bash as its shell; thus, you use gawk the same way you would under Unix. Ifthese steps do not work, please send in a bug report (see Section B.5 [Reporting Problemsand Bugs], page 280).B.4.3 Installing gawk on a TandemThe Tandem port is only minimally supported. The port’s contributor no longer has accessto a Tandem system.The Tandem port was done on a Cyclone machine running D20. The port is pretty cleanand all facilities seem to work except for the I/O piping facilities (see Section 3.8.5 [Usinggetline from a Pipe], page 54, Section 3.8.6 [Using getline into a Variable from a Pipe],
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