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diff --git a/README.DOS.template b/README.DOS.template new file mode 100644 index 0000000..49fd0e7 --- /dev/null +++ b/README.DOS.template @@ -0,0 +1,257 @@ +Port of GNU Make to 32-bit protected mode on MSDOS and MS-Windows. + +Builds with DJGPP v2 port of GNU C/C++ compiler and utilities. + + +New (since 3.74) DOS-specific features: + + 1. Supports long filenames when run from DOS box on Windows 95. + + 2. Supports both stock DOS COMMAND.COM and Unix-style shells + (details in ``Notes'' below). + + 3. Supports DOS drive letters in dependencies and pattern rules. + + 4. Better support for DOS-style backslashes in pathnames (but see + ``Notes'' below). + + 5. The $(shell) built-in can run arbitrary complex commands, + including pipes and redirection, even when COMMAND.COM is your + shell. + + 6. Can be built without floating-point code (see below). + + 7. Supports signals in child programs and restores the original + directory if the child was interrupted. + + 8. Can be built without (a previous version of) Make. + + +To build: + + 1. Unzip the archive, preserving the directory structure (-d switch + if you use PKUNZIP). If you build Make on Windows 95, use an + unzip program that supports long filenames in zip files. + + 2. Invoke the `configure.bat' batch file. + + If it doesn't find a working Make, it will suggest to use the + `dosbuild.bat' batch file to build Make. Either do as it + suggests or install another Make program (a pre-compiled binary + should be available from the usual DJGPP sites). + + 3. If you have Make, the configure script will need a Unix-style + Sed program. If you don't have that installed, you can find one + on one of the DJGPP mirror sites. + + 4. If you will need to run Make on machines without an FPU, you + might consider building a version of Make which doesn't issue + floating-point instructions (they don't help much on MSDOS + anyway). To this end, invoke the configure batch file like so: + + configure no-float + + 5. Invoke Make. + + 6. If you have a Unix-style shell installed, you can use the + `install' target. You will also need GNU Fileutils and GNU + Sh-utils for this (they should be available from the DJGPP + sites). + + 7. The `clean' targets require Unix-style `rm' program. + + + +Notes: +----- + + 1. The shell issue. + + This is probably the most significant improvement in this port. + + The original behavior of GNU Make is to invoke commands + directly, as long as they don't include characters special to + the shell or internal shell commands, because that is faster. + When shell features like redirection or filename wildcards are + involved, Make calls the shell. + + This port supports both DOS shells (the stock COMMAND.COM and + its 4DOS/NDOS replacements), and Unix-style shells (tested with + the venerable Stewartson's `ms_sh' 2.3 and the recent DJGPP port + of `bash' by Daisuke Aoyama <jack@st.rim.or.jp>). + + When the $SHELL variable points to a Unix-style shell, Make + works just like you'd expect on Unix, calling the shell for any + command that involves characters special to the shell or + internal shell commands. The only difference is that, since + there is no standard way to pass command lines longer than the + infamous DOS 126-character limit, this port of Make writes the + command line to a temporary disk file and then invokes the shell + on that file. + + If $SHELL points to a DOS-style shell, however, Make will not + call it automatically, as it does with Unix shells. Stock + COMMAND.COM is too dumb and would unnecessarily limit the + functionality of Make. For example, you would not be able to + use long command lines in commands that use redirection or + pipes. Therefore, when presented with a DOS shell, this port of + Make will emulate most of the shell functionality, like + redirection and pipes, and shall only call the shell when a + batch file or a command internal to the shell is invoked. (Even + when a command is an internal shell command, Make will first + search the $PATH for it, so that if a Makefile calls `mkdir', + you can install, say, a port of GNU `mkdir' and have it called + in that case.) + + The key to all this is the extended functionality of `spawn' and + `system' functions from the DJGPP library; this port just calls + `system' where it would invoke the shell on Unix. The most + important aspect of these functions is that they use a special + mechanism to pass long (up to 16KB) command lines to DJGPP + programs. In addition, `system' emulates some internal + commands, like `cd' (so that you can now use forward slashes + with it, and can also change the drive if the directory is on + another drive). Another aspect worth mentioning is that you can + call Unix shell scripts directly, provided that the shell whose + name is mentioned on the first line of the script is installed + anywhere along the $PATH. It is impossible to tell here + everything about these functions; refer to the DJGPP library + reference for more details. + + The $(shell) built-in is implemented in this port by calling + `popen'. Since `popen' calls `system', the above considerations + are valid for $(shell) as well. In particular, you can put + arbitrary complex commands, including pipes and redirection, + inside $(shell), which is in many cases a valid substitute for + the Unix-style command substitution (`command`) feature. + + + 2. "SHELL=/bin/sh" -- or is it? + + Many Unix Makefiles include a line which sets the SHELL, for + those versions of Make which don't have this as the default. + Since many DOS systems don't have `sh' installed (in fact, most + of them don't even have a `/bin' directory), this port takes + such directives with a grain of salt. It will only honor such a + directive if the basename of the shell name (like `sh' in the + above example) can indeed be found in the directory that is + mentioned in the SHELL= line (`/bin' in the above example), or + in the current working directory, or anywhere on the $PATH (in + that order). If the basename doesn't include a filename + extension, Make will look for any known extension that indicates + an executable file (.exe, .com, .bat, .btm, .sh, and even .sed + and .pl). If any such file is found, then $SHELL will be + defined to the exact pathname of that file, and that shell will + hence be used for the rest of processing. But if the named + shell is *not* found, the line which sets it will be effectively + ignored, leaving the value of $SHELL as it was before. Since a + lot of decisions that this port makes depend on the gender of + the shell, I feel it doesn't make any sense to tailor Make's + behavior to a shell which is nowhere to be found. + + Note that the above special handling of "SHELL=" only happens + for Makefiles; if you set $SHELL in the environment or on the + Make command line, you are expected to give the complete + pathname of the shell, including the filename extension. + + The default value of $SHELL is computed as on Unix (see the Make + manual for details), except that if $SHELL is not defined in the + environment, $COMSPEC is used. Also, if an environment variable + named $MAKESHELL is defined, it takes precedence over both + $COMSPEC and $SHELL. Note that, unlike Unix, $SHELL in the + environment *is* used to set the shell (since on MSDOS, it's + unlikely that the interactive shell will not be suitable for + Makefile processing). + + The bottom line is that you can now write Makefiles where some + of the targets require a real (i.e. Unix-like) shell, which will + nevertheless work when such shell is not available (provided, of + course, that the commands which should always work, don't + require such a shell). More important, you can convert Unix + Makefiles to MSDOS and leave the line which sets the shell + intact, so that people who do have Unixy shell could use it for + targets which aren't converted to DOS (like `install' and + `uninstall', for example). + + + 3. Default directories. + + GNU Make knows about standard directories where it searches for + library and include files mentioned in the Makefile. Since + MSDOS machines don't have standard places for these, this port + will search ${DJDIR}/lib and ${DJDIR}/include respectively. + $DJDIR is defined automatically by the DJGPP startup code as the + root of the DJGPP installation tree (unless you've tampered with + the DJGPP.ENV file). This should provide reasonable default + values, unless you moved parts of DJGPP to other directories. + + + 4. Letter-case in filenames. + + If you run Make on Windows 95, you should be aware of the + letter-case issue. Make is internally case-sensitive, but all + file operations are case-insensitive on Windows 95, so + e.g. files `FAQ', `faq' and `Faq' all refer to the same file, as + far as Windows is concerned. The underlying DJGPP C library + functions honor the letter-case of the filenames they get from + the OS, except that by default, they down-case 8+3 DOS filenames + which are stored in upper case in the directory and would break + many Makefiles otherwise. (The details of which filenames are + converted to lower case are explained in the DJGPP libc docs, + under the `_preserve_fncase' and `_lfn_gen_short_fname' + functions, but as a thumb rule, any filename that is stored in + upper case in the directory, is a legal DOS 8+3 filename and + doesn't include characters illegal on MSDOS FAT filesystems, + will be automatically down-cased.) User reports that I have + indicate that this default behavior is generally what you'd + expect; however, since this is the first DJGPP port of Make that + supports long filenames, your input is most welcome. + + In any case, if you hit a situation where you must force Make to + get the 8+3 DOS filenames in upper case, set FNCASE=y in the + environment or in the Makefile. + + + 5. DOS-style pathnames. + + There are a lot of places throughout the program sources which + make implicit assumptions about the pathname syntax. In + particular, the directories are assumed to be separated by `/', + and any pathname which doesn't begin with a `/' is assumed to be + releative to the current directory. This port attempts to + support DOS-style pathnames which might include the drive letter + and use backslashes instead of forward slashes. However, this + support is not complete; I feel that pursuing this support too + far might break some more important features, particularly if + you use a Unix-style shell (where a backslash is a quote + character). I only consider support of backslashes desirable + because some Makefiles invoke non-DJGPP programs which don't + understand forward slashes. A notable example of such programs + is the standard programs which come with MSDOS. Otherwise, you + are advised to stay away from backslashes whenever possible. In + particular, filename globbing won't work on pathnames with + backslashes, because the GNU `glob' library doesn't support them + (backslash is special in filename wildcards, and I didn't want + to break that). + + One feature which *does* work with backslashes is the filename- + related built-in functions such as $(dir), $(notdir), etc. + Drive letters in pathnames are also fully supported. + + + +Bug reports: +----------- + + Bugs that are clearly related to the MSDOS/DJGPP port should be + reported first on the comp.os.msdos.djgpp news group (if you cannot + post to Usenet groups, write to the DJGPP mailing list, + <djgpp@delorie.com>, which is an email gateway into the above news + group). For other bugs, please follow the the procedure explained + in the "Bugs" chapter of the Info docs. If you don't have an Info + reader, look up that chapter in the `make.i1' file with any text + browser/editor. + + + Enjoy, + Eli Zaretskii <eliz@is.elta.co.il> |