Notes on the MS-DOS Perl port Diomidis Spinellis (dds@cc.ic.ac.uk) [0. First copy the files in the msdos directory into the parent directory--law] 1. Compiling. Perl has been compiled under MS-DOS using the Microsoft C compiler version 5.1. Before compiling install dir.h as . You will need a Unix-like make program (e.g. pdmake) and something like yacc (e.g. bison). You could get away by running yacc and dry running make on a Unix host, but I haven't tried it. Compilation takes 12 minutes on a 20MHz 386 machine (together with formating the manual), so you will probably need something to do in the meantime. The executable is 272k and the top level directory needs 1M for sources and about the same ammount for the object code and the executables. The makefile will compile glob for you which you will need to place somewhere in your path so that perl globbing will work correctly. I have not tried all the tests or the examples, nor the awk and sed to Perl translators. You are on your own with them. In the eg directory I have included an example program that uses ioctl to display the charac- teristics of the storage devices of the system. 2. Using MS-DOS Perl The MS-DOS version of perl has most of the functional- ity of the Unix version. Functions that can not be provided under MS-DOS like sockets, password and host database access, fork and wait have been ommited and will terminate with a fatal error. Care has been taken to implement the rest. In particular directory access, redirection (includ- ing pipes, but excluding the pipe function), system, ioctl and sleep have been provided. [Files currently can be edited in-place provided you are cre- ating a backup. However, if the backup coincidentally has the same name as the original, or if the resulting backup filename is invalid, then the file will probably be trashed. For example, don't do perl -i~ script makefile perl -i.bak script file.dat because (1) MS-DOS treats "makefile~" and "makefile" as the same filename, and (2) "file.dat.bak" is an invalid filename. The files "makefile" and "file.dat" will probably be lost forever. Moral of the story: Don't use in-place editing under MS-DOS. --rjc] 2.1. Interface to the MS-DOS ioctl system call. The function code of the ioctl function (the second argument) is encoded as follows: - The lowest nibble of the function code goes to AL. - The two middle nibbles go to CL. - The high nibble goes to CH. The return code is -1 in the case of an error and if successful: - for functions AL = 00, 09, 0a the value of the register DX - for functions AL = 02 - 08, 0e the value of the register AX - for functions AL = 01, 0b - 0f the number 0. See the perl manual for instruction on how to distin- guish between the return value and the success of ioctl. Some ioctl functions need a number as the first argu- ment. Provided that no other files have been opened the number can be obtained if ioctl is called with @fdnum[number] as the first argument after executing the following code: @fdnum = ("STDIN", "STDOUT", "STDERR"); $maxdrives = 15; for ($i = 3; $i < $maxdrives; $i++) { open("FD$i", "nul"); @fdnum[$i - 1] = "FD$i"; } 2.2. Binary file access Files are opened in text mode by default. This means that CR LF pairs are translated to LF. If binary access is needed the `binary' function should be used. There is currently no way to reverse the effect of the binary func- tion. If that is needed close and reopen the file. 2.3. Interpreter startup. The effect of the Unix #!/bin/perl interpreter startup can be obtained under MS-DOS by giving the script a .bat extension and using the following lines on its begining: @REM=(" @perl %0.bat %1 %2 %3 %4 %5 %6 %7 %8 %9 @end ") if 0 ; (Note that you will probably want an absolute path name in front of %0.bat). March 1990 Diomidis Spinellis Myrsinis 1 GR-145 62 Kifissia Greece -------------------------------------------------------------------------- Revisions to the MS-DOS support in Perl 4.0 Tom Dinger, 18 March 1991 The DOS compatibility added to Perl sometime in release 3.x was not maintained, and Perl as distributed could not be built without changes. Both myself and Len Reed more or less "rediscovered" how to get Perl built and running reliably for MS-DOS, using the Microsoft C compiler. He and I have communicated, and will be putting together additional patches for the DOS version of Perl. 1. Compiling Perl For now, I have not supplied a makefile, as there is no standard for make utilities under DOS. All the files can be compiled with Microsoft C 5.1, using the switches "-AL -Ox" for Large memory model, maximum optimization (this turned out a few code generation bugs in MSC 5.1). The code will also compile with MSC 6.00A, with the optimization "-Oacegils /Gs" for all files (regcomp.c has special case code to change the aliasing optimizations). Generally, you follow the instructions given above to compile and build Perl 4.0 for DOS. I used the output of SunOS yacc run on perly.y, without modification, but I expect both Bison and Berkeley-YACC will work also. From inspection of the generated code, however, I believe AT&T derived YACC produces the smallest tables, i.e. uses the least memory. This is important for a 300K executable file. 2. Editing in-place. You will need the file suffix.c from the os2 subdirectory -- it will create a backup file with much less danger for DOS. 3. A "Smarter" chdir() function. I have added to the DOS version of Perl 4.0 a replacement chdir() function. Unlike the "normal" behavior, it is aware of drive letters at the start of paths for DOS. So for example: perl_chdir( "B:" ) changes to the default directory, on drive B: perl_chdir( "C:\FOO" ) changes to the specified directory, on drive C: perl_chdir( "\BAR" ) changes to the specified directory on the current drive. 4. *.BAT Scripts as Perl scripts The strategy described above for turning a Perl script into a *.BAT script do not work. I have been using the following lines at the beginning of a Perl *.BAT script: @REM=(qq! @perl -S %0.bat %1 %2 %3 %4 %5 %6 %7 %8 %9 @goto end !) if 0 ; and the following at the end of the *.BAT script: @REM=(qq! :end !) if 0 ; If you like, with the proper editor you can replace the four '!' characters with some untypeable character, such as Ctrl-A. This will allow you to pass any characters, including ".." strings as arguments. 4. Things to Come * Better temporary file handling. * A real Makefile -- Len Reed has one for Dmake 3.6 * Swapping code -- swaps most of Perl out of memory (to EMS, XMS or disk) before running a sub-program or pipe. * MKS command line support, both into Perl, and to other programs spawned by Perl. * Smarter pipe functions, not using COMMAND.COM. Tom Dinger tdinger@East.Sun.COM Martch 18, 1991