Tofrodos

Contents

• What is Tofrodos?
• How to Use Tofrodos
• How to Install Tofrodos
  • Linux, macOS and Unix-type Systems
  • Windows
  • MSDOS, FreeDOS and Clones
• Compiling Tofrodos for Linux, macOS and Unix-type Systems
• Compiling Tofrodos for Windows
• Compiling Tofrodos for MSDOS
• Porting to Other Systems
• History of Changes
• Copyright and Licence

What is Tofrodos?

DOS (and Windows) text files traditionally have CR/LF (carriage return/line feed) pairs as their new line delimiters while Unix text files traditionally have LFs (line feeds) to terminate each line.

Tofrodos comprises two programs, "fromdos" and "todos", which convert ASCII and Unicode UTF-8 text files to and from these formats. Use "fromdos" to convert DOS text files to the Unix format, and "todos" to convert Unix text files to the DOS format.

How to Use Tofrodos

Tofrodos is a command line program. This means that if you use Windows, you will need to open Command Prompt. If you use any of the Unix-type systems like Linux, macOS, etc, you will need to start a shell (for example, bash).

To convert a plain text file with CR-LF line endings (which is used by Windows and DOS) to LF endings (used by Unix-type systems), do:

fromdos file-to-convert.txt

To convert a plain text file with LF to CR-LF, do:

todos file-to-convert.txt

If you have more than one file to convert, you can list them all on the command line at once, like so:

fromdos file1.txt file2.txt file3.txt

or even use wildcard characters, such as

todos *.txt

You can also put the program in a pipe (that is, cause it to get its input from another program and send its output to a third program), like so:

cat some-file.txt | todos | diff - reference.txt

The names todos and fromdos (or "todos.exe" and "fromdos.exe" in Windows) are traditionally the names under which this program is installed. But you can also rename the program files to unix2dos and dos2unix (or "unix2dos.exe" and "dos2unix.exe" in Windows), and they will work just fine. Under the hood, these are all the same program file. Tofrodos checks the name under which it is run (whether "todos", "fromdos", "unix2dos" or "dos2unix") and converts your files accordingly.

That's it. For more advanced options, please see the tofrodos manual. If you use Windows, open tofrodos.html in your web browser. If you use Linux and have installed Tofrodos in the usual way, type man fromdos or man todos.

How to Install Tofrodos

Linux, macOS and Unix-type Systems

If you use Linux, you may be able to get tofrodos from your distribution's repository. For example, on Ubuntu, install it with

sudo apt install tofrodos

Alternatively, you can also compile it youself. See the section Compiling Tofrodos for Linux, macOS and Unix-type Systems.

Windows

Download the binary distribution files from the tofrodos repository's releases page. It contains the precompiled 64-bit executables (binaries) for the Windows console (ie, Command Prompt). Just unpack the contents of the zip file into a directory of your choice.

To read the manual, open tofrodos.html (included in the distribution file) in a web browser.

Note that if you prefer the names "dos2unix.exe" and "unix2dos.exe", just make a copy of "todos.exe" (or "fromdos.exe") under those names. Tofrodos automatically detects the name under which it is run, and will change its behaviour accordingly. (That is, "dos2unix" will convert files from the DOS format to the Unix format, and "unix2dos" will convert files from the Unix format to the DOS format.)

If you wish to compile the program from the sources yourself, either download the sources from the releases page or clone the repository. See the section Compiling Tofrodos for Windows for more information.

MSDOS, FreeDOS and Clones

You will need to compile the sources. See the section Compiling Tofrodos for MSDOS.

Compiling Tofrodos for Linux, macOS and Unix-type Systems

First, get the source code from the Tofrodos repository at
https://www.github.com/ChristopherHeng/tofrodos That is, either download the source zip from the releases page or clone the repository.

Then, to compile everything, just type:

make -f makefile.gcc all

You can then install the binaries to /usr/bin and the man pages to /usr/man/man1 by typing:

make -f makefile.gcc install

Since you're installing the binary and manual page into your system directories with this command, you'll need to be logged in as root. (I know this is stating the obvious, but it's just in case you're new to installing programs.)

To install them somewhere other than the defaults, redefine BINDIR and MANDIR for the binary and manual page destinations respectively. For example, to install the binaries in /usr/local/bin and the manual page in /usr/local/man/man1, do the following:

make -f makefile.gcc BINDIR=/usr/local/bin MANDIR=/usr/local/man/man1 install

Note that macOS does not have a specific directory for man pages. As such, simply typing "make install" will fail on that system. You will need to set MANDIR to some directory that you know exists.

To read the manual page after installation, simply type

man fromdos

If you've installed MANDIR to a non-standard location, so that the above does not work (such as you may have done on macOS), just specify the path, for example:

man ./fromdos.1

Note that if you prefer the names "dos2unix" and "unix2dos", just rename the binaries accordingly and you're done. Tofrodos automatically detects the name under which it is run, and will change its behaviour accordingly. That is, "dos2unix" will convert files from the DOS format to the Unix format, and "unix2dos" will convert files from the Unix format to the DOS format. No code changes are necessary.

Compiling Tofrodos for Windows

You do not actually need to compile Tofrodos for Windows if you don't want to, since you can download the precompiled 64 bit binaries from Tofrodos' releases page

For those who prefer to compile it yourself, either download the source zip from the abovementioned releases page, or clone the repository, which is located at:
https://www.github.com/ChristopherHeng/tofrodos

You will need either Visual Studio or MinGW-w64's gcc.

To compile with Visual Studio, do the following:

nmake -f makefile.vs all

To compile with MinGW-w64, do this instead:

make -f makefile.min all

(Depending on which MinGW-w64 distribution you installed, you may have to invoke it with "mingw32-make" instead of "make".)

The distribution binaries were compiled with Visual Studio.

Compiling Tofrodos for MSDOS

To cross-compile for MSDOS, you will need OpenWatcom C/C++ and compile from Windows, rather than MSDOS, since many of the files have longer filenames than MSDOS can handle.

First, get the source zip from Tofrodos' releases page or clone the repository, which is located at:
https://www.github.com/ChristopherHeng/tofrodos

Next, copy the files src\startup\wildargv.c and src\startup\initarg.h from your WATCOM directory to Tofrodos' lib subdirectory. For example, if you installed Watcom to c:\watcom, and you expanded the tofrodos package into d:\tofrodos, do the following:

copy c:\watcom\src\startup\wildargv.c d:\tofrodos\lib
copy c:\watcom\src\startup\initarg.h d:\tofrodos\lib

The above files are needed so that Tofrodos can process wildcards on the command line.

Then, compile the source using the following command:

wmake -f makefile.wcc TARGET=dos16 all

Alternatively, you can also create a 32-bit version that uses a DOS extender:

wmake -f makefile.wcc TARGET=dos32 all

Make sure you do a

wmake -f makefile.wcc clean

before compiling again for a different target or the response files and object files will be wrong for the new target.

Note that the sources are configured for compilation with the "stable testing" version of OpenWatcom as found on https://openwatcom.org/ftp/source/ow_portable_v2_stable.zip The version I used identified itself as "Version 2.0beta1 LA". If you are using the earlier version 1.9, you may or may not have to tweak config.h to define some compatibility macros and typedefs. I have added information to that file on what to do if you compile with the old version and get errors.

Porting to Other Systems

If you want to compile Tofrodos for a system other than Linux, MSDOS or Windows, you may or may not have some work in store for you. The program is very small, so the work you need to do is probably (hopefully) minimal.

The first place to look into is probably the config.h file, where I tried to place as many system and compiler macros as I could think of.

If you are compiling on other Unix systems, tweaking the config.h file macros may well be all that you need to do. I have reports of success with people using it on macOS, FreeBSD, HP-UX and others.

History of Changes

The dates given are when the code base was finalised and do not necessarily refer to the date of public release.

Version 2.1.1 20 Apr 2026

• [Unix-type systems] fixed bug where Tofrodos was unable to convert a file in a directory that is not writeable by the user, even though the file itself is writeable.

Version 2.1.0 29 Mar 2026

• [All systems except MSDOS] fixed bug where Tofrodos would incorrectly handle files with multiple hard links.
• [Unix-type systems] fixed bug where in certain situations, earlier versions of Tofrodos could fail to correctly determine a file's read/write permissions. It only happens if you try to convert a file that you do not own.
• [All systems] if the --preserve option is used, and Tofrodos is not able to restore the file's original owner and/or time, it will now issue error messages to that effect. It would previously silently fail the change.
• [Unix-type systems] Tofrodos will no longer allow you to convert a read-only file that you are not the owner of, even if you use the --force option. (You can, of course, manually chmod the file to remove the read-only flag if you have the necessary pemissions.)
• In view of the non-trivial bug fixes here, this is a recommended upgrade.

Version 2.0.0 18 March 2026

• [All systems] the long options --unix and --dos have been renamed --unix2dos and --dos2unix respectively to make it easier to remember what it does. You can still type --unix or --dos if you like, since you are allowed to truncate long options provided the letters uniquely identify the option you want. Note: you do not need to use these options if you are using the default names for the program (todos, fromdos, unix2dos or dos2unix), since the direction of conversion is implicit from the name.
• [All systems] added long options --todos and --fromdos, which are synonyms for --unix2dos and --dos2unix respectively, for those who are more familiar with those names.
• [All systems] now checks to make sure the program is named either "todos", "fromdos", "dos2unix" or "unix2dos" or one of the --todos, --fromdos, --unix2dos, --dos2unix, -u, or -d options is specified, otherwise it will not proceed with the conversion. Previously, if the direction of conversion was not clear from the name of the program or from its options, it would assume the conversion was in a particular direction depending on the operating system. This meant that the program behaved differently on different systems if it was given some arbitrary name (other than one of the above).
• [All systems] the documentation has been updated (ie, the manual pages and this README file). The man page and its HTML equivalent are now generated from the same source file, making it easier to update in the future.
• [Windows] now supports the Windows' implementation of symbolic links introduced in Vista in 2007. Note that symlinks have been supported on Unix-type systems (eg, Linux, macOS, *BSD, etc) since 2003 (ver 1.7).
• [Windows] now supports '/' as directory separators (in addition to the usual '\') for pathnames since Windows can also handle these. (Specifically, Windows accepts both separators at the Win32 API level, though not all Windows programs, including Microsoft's own, support it. Now, Tofrodos also supports it.)

Version 1.9.0 10 March 2026

• [All systems] added support for long options (for example, instead of saying typing -h, you can now type --help, etc).
• [All systems] updated Tofrodos' URL to its new home, namely its git repository on GitHub.
• [Windows] the MinGW-w64 makefile has been updated. Apparently, newer versions of MinGW-w64 do not enable wildcard processing by default, so the revised makefile includes an additional module to make sure this is turned on.

Version 1.8.4 8 Jan 2026

• [Windows/MSDOS] fixed bug in my implementation of getopt() due to a misunderstanding of its return value when a missing option argument is encountered. This arose from an incompatibility between the POSIX specification and the BSD's implementation as described in its manual page. We now align with POSIX rather than BSD for this return value. Note that this only affects tofrodos if you compile with Visual Studio or OpenWatcom.
• [All systems except Windows/MSDOS] fixed cryptic error message about an invalid option when what is meant was that a required option argument was missing (it only occurs when the user used the -l option without supplying a filename).
• [Linux] the Linux Software Map (LSM) has been removed. This was an artifact from the 1990s when tofrodos was first written, but I don't think anyone uses it any more.
• [All systems] filelist.txt has been removed. It is unnecessary, and I doubt that anyone even looked at it.

Version 1.8.3 14 June 2024

• [All systems] The -a option, long deprecated since 2013, has been removed.
• [Windows/MSDOS] Options can now only be preceded by a '-' character, to align it with all the other systems (eg, Linux, macOS, etc). (You could previously also use '/'.)
• [Windows] Updated makefiles for MinGW-w64 and Visual Studio
• [Windows] Updated the precompiled binaries to 64-bit versions. If you are still using a 32-bit version of Windows, compile the program yourself using (say) MinGW-w64 with a 32-bit compiler.

Versions 1.8.0 to 1.8.2

• (Internal versions - not publicly released.)

Version 1.7.13 25 October 2013

• [Hurd, NetBSD, FreeBSD kernel] Added support for Hurd, NetBSD and FreeBSD kernel (a system that uses the FreeBSD kernel, but is not necessarily the full FreeBSD system). As a side benefit, tofrodos is slightly more portable since it no longer depends on certain system-specific macros (namely MAXPATHLEN from sys/param.h).
• [All] Tofrodos now displays information on what to do if it is not able to rename the temporary file back to the original filename after a successful conversion.
• [All] The -a option is now documented as "deprecated", since you shouldn't use it unless you have an unusual text file that you're trying to fix.
• [All] Minor improvements to the documentation.

Version 1.7.12 1 October 2012

• [All] Under certain error conditions, Tofrodos may fail to remove the temporary files that it creates. This is now fixed.
• [All] Fixed another bug where an exit code of 0, instead of 1, is returned under certain failure conditions.
• [MSDOS] Although MSDOS is not a multitasking system, and thus should not need it, the DOS port of Tofrodos now also uses my implementation of mkstemp(). This simplifies maintenance since I have fewer code paths to test.
• [Windows] Support for compiling the source code using DJGPP 2, Borland C/C++, LCC-Win32 and Digital Mars C has been removed. Please use one of the other supported compilers (eg, Open Watcom C, etc).
• [All] The documentation now has information about the exit codes returned by Tofrodos.

Version 1.7.11 27 September 2012

• [All] tofrodos now consistently returns an exit code of 1 when there's a failure. Previously, under certain error conditions, it could return an exit code of -1 (which is not a valid exit code for some operating systems).
• [Windows] This version now includes an implementation of mkstemp() for Windows (when compiled with Open Watcom C), bringing the Windows (Open Watcom) port of tofrodos up to par with versions for systems like Linux and Mac OS X which provide mkstemp() in their C libraries. Hopefully, this will help those of you who run multiple instances of tofrodos at the same time in the same directory.
• [Windows] Fixed a bug introduced in 1.7.9 where the Windows port of tofrodos always creates the temporary file in the current directory instead of the directory where the target file is.
• [Mac OS X] The Mac OS X port of tofrodos now uses mkstemp() to create the temporary file the way it does on Linux.
• [Mac OS X] Added more information in readme.txt for Mac users.
• [All] Improved documentation about the -p and -b options.

Version 1.7.10 25 September 2012

• Limited (beta) distribution only, not released for general use. If you have this version, please upgrade to 1.7.11.

Version 1.7.9 21 February 2011

• [Windows, Linux, Mac OS X, Unix] The behaviour of the -b option (create backup file) has been changed to be more useful on systems with support for long filenames and an arbitrary number of file extensions (ie, all systems except MSDOS). It now backs up "filename.ext" as "filename.ext.bak" instead of "filename.bak". Note that with this version, the DOS version no longer behaves the same way (when the -b option is used) as the Windows, Linux, Mac OS X, *BSD and other Unix versions, since DOS systems have filename limitations. At least this way, we're not held back by the least common denominator (DOS), especially since few people use DOS nowadays.
• [All] The documentation has been updated to explain the behaviour of the -b option in more detail.

Version 1.7.8 8 April 2008

• [Mac OS X] Fixed corrupted portion of config.h that only shows up when compiling under Mac OS X (sorry - I don't know what happened)

Version 1.7.7 1 April 2008

• [Mac OS X] Added support for compiling tofrodos under Mac OS X.
• [FreeBSD] Added support for compiling tofrodos under FreeBSD.
• [OpenBSD] Added support for compiling tofrodos under OpenBSD (not tested).
• [All] Fixed typos in documentation (Unix man page and HTML version).

Version 1.7.6 15 March 2005

• [All systems] New option: -l allows you to send the error messages to a log file. It's particularly convenient for systems with less powerful command line shells that do not allow you to easily redirect stderr.
• [All systems] Fixed: all error and verbose messages are now sent to stderr or the error log file (if -l is given).
• [Windows] Older versions of compilers like Borland 4.X and 5.0, Watcom 10.X and Visual C++ 6.0 no longer have makefiles. Use the latest versions; all these compilers are now available free of charge from their vendors so using the latest version to compile tofrodos should not be a great hardship.
• [All systems] Other minor fixes.

Version 1.7 26 November 2003

• [Linux/Unix] Bug fix: now handles symbolic link arguments correctly. This bug only affects Unix-type sytems (like Linux, FreeBSD, OpenBSD, etc).
• [Linux] tofrodos now uses mkstemp() to create the temporary file to avoid a race between file name creation and opening which may occur when using mktemp(). If you use a non-Linux system, and have mkstemp(), you can take advantage of this by defining HAVE_MKSTEMP in config.h (defined by default for Linux only).
• [Linux/Unix] "make install" now installs to /usr/bin by default (you can still change this easily) since Linux distributions using tofrodos appear to use this value. (Makes it easier for maintainers of those distributions.)
• [All systems] Made some error messages a bit more informative.
• [All systems] Verbose mode is slightly more informative.
• [Windows] Added support for compiling with the MinGW (GNU) C Compiler on Win32 systems.
• [All systems] Added an HTML version of the manual page. Useful for systems that don't have a built-in facility to read a man page (like MSDOS and Windows).

Version 1.6 1 July 2002

• Added support for LCC-Win32 and BCC 5.5

Version 1.5 19 June 2002

• Minor fixes to documentation.
• Added support for the Digital Mars C/C++ compiler (Win32 console mode)

Version 1.4 16 March 1999

• Fixed bug when using -b on a file not in the current directory.
• Added RPM support.

Version 1.3 8 October 1997

• Added new option (-p) to preserve file ownership and time.
• Added support for Win32 compilation and some compilers under DOS and Windows.

Version 1.2 5 April 1997

• (Internal version - not publicly released.)

Version 1.1 16 December 1996

• Fixed bug in creation of temporary filename on Linux.
• Fixed bug in creation of backup filename on Linux.

Version 1.0 22 June 1996

• Initial version.

Copyright and Licence

The program and its accompanying files and documentation are
Copyright 1996-2026 Christopher Heng. All rights reserved.

The included getopt.c and getopt.h are distributed under the terms of the GNU General Public License Version 3, a copy of which is enclosed in this package in the file COPYING-GPL3.txt

The other files are distributed under the terms of the GNU General Public License Version 2, which you can find in the file COPYING-GPL2.txt.

You can get the latest version of tofrodos from its repository at:
https://github.com/ChristopherHeng/tofrodos

Bugs can be reported there in the usual way.