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=pod

=head1 NAME

dos2unix - DOS/Mac to Unix and vice versa text file format converter

=head1 SYNOPSIS

    dos2unix [options] [FILE ...] [-n INFILE OUTFILE ...]
    unix2dos [options] [FILE ...] [-n INFILE OUTFILE ...]

=head1 DESCRIPTION

The Dos2unix package includes utilities C<dos2unix> and C<unix2dos> to convert
plain text files in DOS or Mac format to Unix format and vice versa.

In DOS/Windows text files a line break, also known as newline, is a combination
of two characters: a Carriage Return (CR) followed by a Line Feed (LF). In Unix
text files a line break is a single character: the Line Feed (LF). In Mac text
files, prior to Mac OS X, a line break was single Carriage Return (CR)
character. Nowadays Mac OS uses Unix style (LF) line breaks.

Binary files are automatically skipped, unless conversion is forced.

Non-regular files, such as directories and FIFOs, are automatically skipped.

Symbolic links and their targets are by default kept untouched.
Symbolic links can optionally be replaced, or the output can be written
to the symbolic link target.
Symbolic links on Windows are not supported. Windows symbolic links
always replaced, keeping the targets unchanged.

Dos2unix was modelled after dos2unix under SunOS/Solaris and has similar
conversion modes.

=head1 OPTIONS

=over 4

=item B<-->

Treat all following options as file names. Use this option if you want to
convert files whose names start with a dash. For instance to convert
a file named "-foo", you can use this command:

    dos2unix -- -foo

Or in new file mode:

    dos2unix -n -- -foo out.txt

=item B<-ascii>

Convert only line breaks. This is the default conversion mode.

=item B<-iso>

Conversion between DOS and ISO-8859-1 character set. See also section
CONVERSION MODES.

=item B<-1252>

Use Windows code page 1252 (Western European).

=item B<-437>

Use DOS code page 437 (US). This is the default code page used for ISO conversion.

=item B<-850>

Use DOS code page 850 (Western European).

=item B<-860>

Use DOS code page 860 (Portuguese).

=item B<-863>

Use DOS code page 863 (French Canadian).

=item B<-865>

Use DOS code page 865 (Nordic).

=item B<-7>

Convert 8 bit characters to 7 bit space.

=item B<-c, --convmode CONVMODE>

Set conversion mode. Where CONVMODE is one of:
I<ascii>, I<7bit>, I<iso>, I<mac>
with ascii being the default.

=item B<-f, --force>

Force conversion of binary files.

=item B<-h, --help>

Display help and exit.

=item B<-k, --keepdate>

Keep the date stamp of output file same as input file.

=item B<-L, --license>

Display program's license.

=item B<-l, --newline>

Add additional newline.

B<dos2unix>: Only DOS line breaks are changed to two Unix line breaks.
In Mac mode only Mac line breaks are changed to two Unix
line breaks.

B<unix2dos>: Only Unix line breaks are changed to two DOS line breaks.
In Mac mode Unix line breaks are changed to two Mac line breaks.

=item B<-m, --add-bom>

Write an UTF-8 Byte Order Mark in the output file. Never use this option when
the output encoding is other than UTF-8. See also section UNICODE.

=item B<-n, --newfile INFILE OUTFILE ...>

New file mode. Convert file INFILE and write output to file OUTFILE.
File names must be given in pairs and wildcard names should I<not> be
used or you I<will> lose your files.

The person who starts the conversion in new file (paired) mode will be the owner
of the converted file. The read/write permissions of the new file will be the
permissions of the original file minus the umask(1) of the person who runs the
conversion.

=item B<-o, --oldfile FILE ...>

Old file mode. Convert file FILE and overwrite output to it. The program
defaults to run in this mode. Wildcard names may be used.

In old file (in-place) mode the converted file gets the same owner, group, and
read/write permissions as the original file. Also when the file is converted by
another user who has write permissions on the file (e.g. user root).  The
conversion will be aborted when it is not possible to preserve the original
values.  Change of owner could mean that the original owner is not able to read
the file any more. Change of group could be a security risk, the file could be
made readable for persons for whom it is not intended.  Preservation of owner,
group, and read/write permissions is only supported on Unix.

=item B<-q, --quiet>

Quiet mode. Suppress all warnings and messages. The return value is zero.
Except when wrong command-line options are used.

=item B<-s, --safe>

Skip binary files (default).

=item B<-F, --follow-symlink>

Follow symbolic links and convert the targets.

=item B<-R, --replace-symlink>

Replace symbolic links with converted files
(original target files remain unchanged).

=item B<-S, --skip-symlink>

Keep symbolic links and targets unchanged (default).

=item B<-V, --version>

Display version information and exit.

=back

=head1 MAC MODE

In normal mode line breaks are converted from DOS to Unix and vice versa.
Mac line breaks are not converted.

In Mac mode line breaks are converted from Mac to Unix and vice versa. DOS
line breaks are not changed.

To run in Mac mode use the command-line option C<-c mac> or use the
commands C<mac2unix> or C<unix2mac>.

=head1 CONVERSION MODES

Conversion modes I<ascii>, I<7bit>, and I<iso>
are similar to those of dos2unix/unix2dos under SunOS/Solaris.

=over 4

=item B<ascii>

In mode C<ascii> only line breaks are converted. This is the default
conversion mode.

Although the name of this mode is ASCII, which is a 7 bit standard, the
actual mode is 8 bit. Use always this mode when converting Unicode UTF-8
files.

=item B<7bit>

In this mode all 8 bit non-ASCII characters (with values from 128 to 255)
are converted to a 7 bit space.

=item B<iso>

Characters are converted between a DOS character set (code page) and ISO
character set ISO-8859-1 (Latin-1) on Unix. DOS characters without ISO-8859-1
equivalent, for which conversion is not possible, are converted to a dot. The
same counts for ISO-8859-1 characters without DOS counterpart.

When only option C<-iso> is used dos2unix will try to determine the active code
page. When this is not possible dos2unix will use default code page CP437,
which is mainly used in the USA.  To force a specific code page use options
C<-437> (US), C<-850> (Western European), C<-860> (Portuguese), C<-863> (French
Canadian), or C<-865> (Nordic).  Windows code page CP1252 (Western European) is
also supported with option C<-1252>. For other code pages use dos2unix in
combination with iconv(1).  Iconv can convert between a long list of character
encodings.

Never use ISO converion on Unicode text files. It will corrupt UTF-8 encoded files.

Some examples:

Convert from DOS default code page to Unix Latin-1

    dos2unix -iso -n in.txt out.txt

Convert from DOS CP850 to Unix Latin-1

    dos2unix -850 -n in.txt out.txt

Convert from Windows CP1252 to Unix Latin-1

    dos2unix -1252 -n in.txt out.txt

Convert from Windows CP1252 to Unix UTF-8 (Unicode)

    iconv -f CP1252 -t UTF-8 in.txt | dos2unix > out.txt

Convert from Unix Latin-1 to DOS default code page.

    unix2dos -iso -n in.txt out.txt

Convert from Unix Latin-1 to DOS CP850

    unix2dos -850 -n in.txt out.txt

Convert from Unix Latin-1 to Windows CP1252

    unix2dos -1252 -n in.txt out.txt

Convert from Unix UTF-8 (Unicode) to Windows CP1252

    unix2dos < in.txt | iconv -f UTF-8 -t CP1252 > out.txt

See also L<http://czyborra.com/charsets/codepages.html>
and L<http://czyborra.com/charsets/iso8859.html>.

=back

=head1 UNICODE

=head2 Encodings

There exist different Unicode encodings. On Unix and Linux Unicode files are
typically encoded in UTF-8 encoding. On Windows Unicode text files can be
encoded in UTF-8, UTF-16, or UTF-16 big endian, but are mostly encoded in
UTF-16 format.

=head2 Conversion

Unicode text files can have DOS, Unix or Mac line breaks, like regular text
files.

All versions of dos2unix and unix2dos can convert UTF-8 encoded files, because
UTF-8 was designed for backward compatiblity with ASCII.

Dos2unix and unix2dos with Unicode UTF-16 support, can read little and big
endian UTF-16 encoded text files. To see if dos2unix was built with UTF-16
support type C<dos2unix -V>.

The Windows versions of dos2unix and unix2dos convert UTF-16 encoded files
always to UTF-8 encoded files. Unix versions of dos2unix/unix2dos convert
UTF-16 encoded files to the locale character encoding when it is set to UTF-8.
Use the locale(1) command to find out what the locale character encoding is.

Because UTF-8 formatted text files are well supported on both Windows and Unix,
dos2unix and unix2dos have no option to write UTF-16 files. All UTF-16
characters can be encoded in UTF-8. Conversion from UTF-16 to UTF-8 is without
loss. UTF-16 files will be skipped on Unix when the locale character encoding
is not UTF-8, to prevent accidental loss of text. When an UTF-16 to UTF-8
conversion error occurs, for instance when the UTF-16 input file contains
an error, the file will be skipped.

ISO and 7-bit mode conversion do not work on UTF-16 files.

=head2 Byte Order Mark

On Windows Unicode text files typically have a Byte Order Mark (BOM), because
many Windows programs (including Notepad) add BOMs by default. See also
L<http://en.wikipedia.org/wiki/Byte_order_mark>.

On Unix Unicode files typically don't have a BOM. It is assumed that text files
are encoded in the locale character encoding.

Dos2unix can only detect if a file is in UTF-16 format if the file has a BOM.
When an UTF-16 file doesn't have a BOM, dos2unix will see the file as a binary
file.

Use dos2unix in combination with iconv(1) to convert an UTF-16 file without
BOM.

Dos2unix never writes a BOM in the output file, unless you use option C<-m>.

Unix2dos writes a BOM in the output file when the input file has a BOM, or
when option C<-m> is used.

=head2 Unicode examples

Convert from Windows UTF-16 (with BOM) to Unix UTF-8

    dos2unix -n in.txt out.txt

Convert from Windows UTF-16 (without BOM) to Unix UTF-8

    iconv -f UTF-16 -t UTF-8 in.txt | dos2unix > out.txt

Convert from Unix UTF-8 to Windows UTF-8 with BOM

    unix2dos -m -n in.txt out.txt

Convert from Unix UTF-8 to Windows UTF-16

    unix2dos < in.txt | iconv -f UTF-8 -t UTF-16 > out.txt

=head1 EXAMPLES

Read input from 'stdin' and write output to 'stdout'.

    dos2unix
    dos2unix -l -c mac

Convert and replace a.txt. Convert and replace b.txt.

    dos2unix a.txt b.txt
    dos2unix -o a.txt b.txt

Convert and replace a.txt in ascii conversion mode.

    dos2unix a.txt

Convert and replace a.txt in ascii conversion mode.
Convert and replace b.txt in 7bit conversion mode.

    dos2unix a.txt -c 7bit b.txt
    dos2unix -c ascii a.txt -c 7bit b.txt
    dos2unix -ascii a.txt -7 b.txt

Convert a.txt from Mac to Unix format.

    dos2unix -c mac a.txt
    mac2unix a.txt

Convert a.txt from Unix to Mac format.

    unix2dos -c mac a.txt
    unix2mac a.txt

Convert and replace a.txt while keeping original date stamp.

    dos2unix -k a.txt
    dos2unix -k -o a.txt

Convert a.txt and write to e.txt.

    dos2unix -n a.txt e.txt

Convert a.txt and write to e.txt, keep date stamp of e.txt same as a.txt.

    dos2unix -k -n a.txt e.txt

Convert and replace a.txt. Convert b.txt and write to e.txt.

    dos2unix a.txt -n b.txt e.txt
    dos2unix -o a.txt -n b.txt e.txt

Convert c.txt and write to e.txt. Convert and replace a.txt.
Convert and replace b.txt. Convert d.txt and write to f.txt.

    dos2unix -n c.txt e.txt -o a.txt b.txt -n d.txt f.txt

=head1 RECURSIVE CONVERSION

Use dos2unix in combination with the find(1) and xargs(1) commands to
recursively convert text files in a directory tree structure. For instance to
convert all .txt files in the directory tree under the current directory type:

    find . -name *.txt |xargs dos2unix

=head1 LOCALIZATION

=over 4

=item B<LANG>

The primary language is selected with the environment variable LANG. The LANG
variable consists out of several parts. The first part is in small letters the
language code. The second is optional and is the country code in capital
letters, preceded with an underscore. There is also an optional third part:
character encoding, preceded with a dot. A few examples for POSIX standard type
shells:

    export LANG=nl               Dutch
    export LANG=nl_NL            Dutch, The Netherlands
    export LANG=nl_BE            Dutch, Belgium
    export LANG=es_ES            Spanish, Spain
    export LANG=es_MX            Spanish, Mexico
    export LANG=en_US.iso88591   English, USA, Latin-1 encoding
    export LANG=en_GB.UTF-8      English, UK, UTF-8 encoding

For a complete list of language and country codes see the gettext manual:
L<http://www.gnu.org/software/gettext/manual/gettext.html#Language-Codes>

On Unix systems you can use to command locale(1) to get locale specific
information.

=item B<LANGUAGE>

With the LANGUAGE environment variable you can specify a priority list of
languages, separated by colons. Dos2unix gives preference to LANGUAGE over LANG.
For instance, first Dutch and then German: C<LANGUAGE=nl:de>. You have to first
enable localization, by setting LANG (or LC_ALL) to a value other than
"C", before you can use a language priority list through the LANGUAGE
variable. See also the gettext manual:
L<http://www.gnu.org/software/gettext/manual/gettext.html#The-LANGUAGE-variable>

If you select a language which is not available you will get the
standard English messages.


=item B<DOS2UNIX_LOCALEDIR>

With the environment variable DOS2UNIX_LOCALEDIR the LOCALEDIR set
during compilation can be overruled. LOCALEDIR is used to find the
language files. The GNU default value is C</usr/local/share/locale>.
Option B<--version> will display the LOCALEDIR that is used.

Example (POSIX shell):

    export DOS2UNIX_LOCALEDIR=$HOME/share/locale

=back


=head1 RETURN VALUE

On success, zero is returned.  When a system error occurs the last system error will be
returned. For other errors 1 is returned.

The return value is always zero in quiet mode, except when wrong command-line options
are used.

=head1 STANDARDS

L<http://en.wikipedia.org/wiki/Text_file>

L<http://en.wikipedia.org/wiki/Carriage_return>

L<http://en.wikipedia.org/wiki/Newline>

L<http://en.wikipedia.org/wiki/Unicode>

=head1 AUTHORS

Benjamin Lin - <blin@socs.uts.edu.au>
Bernd Johannes Wuebben (mac2unix mode) - <wuebben@kde.org>,
Christian Wurll (add extra newline) - <wurll@ira.uka.de>,
Erwin Waterlander - <waterlan@xs4all.nl> (Maintainer)

Project page: L<http://waterlan.home.xs4all.nl/dos2unix.html>

SourceForge page: L<http://sourceforge.net/projects/dos2unix/>

Freecode: L<http://freecode.com/projects/dos2unix>

=head1 SEE ALSO

file(1)
find(1)
iconv(1)
locale(1)
xargs(1)

=cut
