NAME
    upx - compress or expand executable files

SYNOPSIS
    upx [ *command* ] [ *options* ] *filename*...

ABSTRACT
                The Ultimate Packer for eXecutables
      Copyright (c) 1996-2000 Markus Oberhumer & Laszlo Molnar
           http://wildsau.idv.uni-linz.ac.at/mfx/upx.html
                      http://www.nexus.hu/upx
                        http://upx.tsx.org

    UPX is a portable, extendable, high-performance executable
    packer for several different executable formats. It achieves an
    excellent compression ratio and offers **very** fast
    decompression. Your executables suffer no memory overhead or
    other drawbacks for most of the formats supported.

    While you may use UPX freely for both non-commercial and
    commercial executables (for details see the file LICENSE), we
    would highly appreciate if you credit UPX and ourselves in the
    documentation, possibly including a reference to the UPX home
    page. Thanks.

    [ Using UPX in non-OpenSource applications without proper
    credits is considered not politically correct ;-) ]

DISCLAIMER
    UPX comes with ABSOLUTELY NO WARRANTY; for details see the file
    LICENSE.

    Having said that, we think that UPX is quite stable now. Indeed
    we have compressed lots of files without any problems. Also, the
    current version has undergone several months of beta testing -
    actually it's almost 2 years since our first public beta.

    This is the first production quality release, and we plan that
    future 1.xx releases will be backward compatible with this
    version.

    Please report all problems or suggestions to the authors.
    Thanks.

DESCRIPTION
    UPX is a versatile executable packer with the following
    features:

      - excellent compression ratio: compresses better than zip/gzip,
          use UPX to decrease the size of your distribution !

      - very fast decompression: about 10 MB/sec even on my old Pentium 133

      - no memory overhead for your compressed executables for most of the
          supported formats

      - safe: you can list, test and unpack your executables
          Also, a checksum of both the compressed and uncompressed file is
          maintained internally.

      - universal: UPX can pack a number of executable formats:
          * dos/exe
          * dos/sys
          * dos/com
          * djgpp2/coff
          * watcom/le (supporting DOS4G, PMODE/W, DOS32a and CauseWay)
          * win32/pe
          * rtm32/pe
          * tmt/adam
          * linux/i386
          * atari/tos

      - portable: UPX is written in portable endian-neutral C++

      - extendable: because of the class layout it's very easy to support
          new executable formats or add new compression algorithms

      - free: UPX can be distributed and used freely. And from version 0.99
          the full source code of UPX is released under the GNU General Public
          License (GPL) !

    You probably understand now why we call UPX the "*ultimate*"
    executable packer.

COMMANDS
  Compress

    This is the default operation, eg. upx yourfile.exe will
    compress the file specified on the command line.

  Decompress

    All UPX supported file formats can be unpacked using the -d
    switch, eg. upx -d yourfile.exe will uncompress the file you've
    just compressed.

  Test

    The -t command tests the integrity of the compressed and
    uncompressed data, eg. upx -t yourfile.exe check whether your
    file can be safely decompressed. Note, that this command doesn't
    check the whole file, only the part that will be uncompressed
    during program execution. This means that you should not use
    this command instead of a virus checker.

  List

    The -l command prints out some information about the compressed
    files specified on the command line as parameters, eg upx -l
    yourfile.exe shows the compressed / uncompressed size and the
    compression ratio of *yourfile.exe*.

OPTIONS
    -q: be quiet, suppress warnings

    -q -q (or -qq): be very quiet, suppress errors

    -q -q -q (or -qqq): produce no output at all

    --help: prints the help

    --version: print the version of UPX

    --stdout: writes all output to stdout

    [ ...to be written... - type `upx --help' for now ]

COMPRESSION LEVELS & TUNING
    UPX offers ten different compression levels from -1 to -9, and -
    -best. The default compression level is -7.

    *   Compression levels 1, 2 and 3 are pretty fast.

    *   Compression levels 4, 5 and 6 achieve a good time/ratio
        performance.

    *   Compression levels 7, 8 and 9 favor compression ratio over
        speed.

    *   Compression level --best may take a very long time.

    Note that compression level -9 can be quite slow for some large
    files, but you definitely should use it when releasing a final
    version of your program. (E.g. it took about 20 minutes to
    compress the almost 5 MB MAME 0.34 with -9 on my Pentium 133,
    but the resulting executable was still ~65 kB smaller than when
    using -7.)

    Since UPX 0.70 there is also an extra compression level --best
    which squeezes out even some more compression ratio. While it is
    usually fine to use this option with your favorite .com file it
    may take several hours to compress a multi-megabyte program. You
    have been warned.

    Tips for even better compression:

    *   Try if --overlay=strip works.

    *   For win32/pe programs there's --strip-relocs=0. See notes below.

OVERLAY HANDLING OPTIONS
    UPX handles overlays like many other executable packers do: it
    simply copies the overlay after the compressed image. This works
    with some files, but doesn't work with others.

    Since version 0.90 UPX defaults to --overlay=copy for all
    executable formats.

      --overlay=copy    Copy any extra data attached to the file. [DEFAULT]

      --overlay=strip   Strip any overlay from the program instead of
                        copying it. Be warned, this may make the compressed
                        program crash or otherwise unusable.

      --overlay=skip    Refuse to compress any program which has an overlay.

ENVIRONMENT
    The environment variable UPX can hold a set of default options
    for UPX. These options are interpreted first and can be
    overwritten by explicit command line parameters. For example:

        for DOS/Windows:   set UPX=-9 --compress-icons#1
        for sh/ksh/zsh:    UPX="-9 --compress-icons=1"; export UPX
        for csh/tcsh:      setenv UPX "-9 --compress-icons=1"

    Under DOS/Windows you must use '#' instead of '=' when setting
    the environment variable because of a command.com limitiation.

    On Vax/VMS, the name of the environment variable is UPX_OPT, to
    avoid a conflict with the symbol set for invocation of the
    program.

    Not all of the options are valid in the environment variable -
    UPX will tell you.

    You can use the --no-env option to turn this support off.

NOTES FOR THE SUPPORTED EXECUTABLE FORMATS
  NOTES FOR ATARI/TOS

    This is the executable format used by the Atari ST, a 68000
    based personal computer which was popular in the late '80s.
    Support of this format is only because of nostalgic feelings of
    one of the authors and serves no practical purpose :-).

    Packed programs will be byte-identical to the original after
    uncompression. All debug information will be stripped, though.

    Extra options available for this executable format:

      (none)

  NOTES FOR DOS/COM

    Obviously UPX won't work with executables that want to read data
    from themselves (like some commandline utilities that ship with
    Win95/98).

    Compressed programs only work on a 286+.

    Packed programs will be byte-identical to the original after
    uncompression.

    Maximum uncompressed size: ~65100 bytes.

    Extra options available for this executable format:

      --8086              Create an executable that works on any 8086 CPU.

  NOTES FOR DOS/EXE

    dos/exe stands for all "normal" 16-bit DOS executables.

    Obviously UPX won't work with executables that want to read data
    from themselves (like some command line utilities that ship with
    Win95/98).

    Compressed programs only work on a 286+.

    Extra options available for this executable format:

      --8086              Create an executable that works on any 8086 CPU.

      --no-reloc          Use no relocation records in the exe header.

  NOTES FOR DOS/SYS

    You can only compress plain sys files, sys/exe (two in one)
    combos are not supported.

    Compressed programs only work on a 286+.

    Packed programs will be byte-identical to the original after
    uncompression.

    Maximum uncompressed size: ~65350 bytes.

    Extra options available for this executable format:

      --8086              Create an executable that works on any 8086 CPU.

  NOTES FOR DJGPP2/COFF