Three versions of the dos2unix program, which converts line endings
between the DOS-style CRLF and Unix-style LF.

Ubuntu Linux:
$ dos2unix -h
tofrodos Ver 1.7.8 Converts text files between DOS and Unix formats.
Copyright 1996-2008 by Christopher Heng. All rights reserved.
Usage: dos2unix [options] [file...]
-a      Always convert (DOS to Unix: kill all CRs;
       Unix to DOS: convert all LFs to CRLFs)
-b      Make backup of original file (.bak).
-d      Convert DOS to Unix.
-e      Abort processing files on error in any file.
-f      Force: convert even if file is not writeable.
-h      Display help on usage and quit.
-l file Log most errors and verbose messages to <file>
-o      Overwrite original file (no backup).
-p      Preserve file owner and time.
-u      Convert Unix to DOS.
-v      Verbose.
-V      Show version and quit.

Arch Linux:
$ dos2unix -h
       dos2unix [--verbose|-v] [--test|-t] [--force|-f] \
               [--<x>2<y>|--auto|-<Z>] \
               [<file name> [...]]
       --auto, -A      output will be set based upon auto-detection
                       of source format
       --d2u, -U       perform DOS -> UNIX conversion
       --m2u, -T       perform MAC -> UNIX conversion
       --u2d, -D       perform UNIX -> DOS conversion
       --u2m, -M       perform UNIX -> MAC conversion
       --d2m, -O       perform DOS -> MAC conversion
       --m2d, -C       perform MAC -> DOS conversion

       --force         suppress internal conversion type corrections
                       based on autodetected input format
       --skipbin, -b   skip binary files
       --test, -t      don't write any conversion results; useful with
                       --verbose to just report on source type
       --verbose, -v   print extra information on stderr
       --version, -V   print version information on stderr

- when no options are given then input format will be automatically detected
 and converted as follows:
       DOS -> UNIX
       MAC -> UNIX
       UNIX -> DOS
- same as above applies if --auto option is used
- when no file is given, then stdin is used as input and stdout as output
- binary files will be skipped automatically if option --skipbin
 (or -b) is used
- stray '\r' characters (without a following '\n') in files in DOS format are
 reported but only conversion 'DOS -> Unix' affects them (they are skipped)
- stray '\n' characters in files in MAC format are not detected for now

Mac OSX (FreeBSD):
dos2unix 5.1.1 (2010-08-18)
Usage: dos2unix [-fhkLlqV] [-c convmode] [-o file ...] [-n infile outfile ...]
-c --convmode    conversion mode
 convmode       ascii, 7bit, iso, mac, default to ascii
-f --force       force conversion of all files
-h --help        give this help
-k --keepdate    keep output file date
-L --license     display software license
-l --newline     add additional newline
-n --newfile     write to new file
 infile         original file in new file mode
 outfile        output file in new file mode
-o --oldfile     write to old file
 file ...       files to convert in old file mode
-q --quiet       quiet mode, suppress all warnings
                always on in stdio mode
-V --version     display version number

$ dos2unix -h
dos2unix: unknown option -- h
usage: dos2unix [-p] [file ...]