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 MiB/sec on an ancient Pentium 133,
about 200 MiB/sec on an Athlon XP 2000+.

- 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:
* atari/tos
* bvmlinuz/386 [bootable Linux kernel]
* djgpp2/coff
* dos/com
* dos/exe
* dos/sys
* linux/386
* linux/elf386
* linux/sh386
* ps1/exe
* rtm32/pe
* tmt/adam
* vmlinuz/386 [bootable Linux kernel]
* vmlinux/386
* watcom/le (supporting DOS4G, PMODE/W, DOS32a and CauseWay)
* win32/pe (exe and dll)
* win64/pe (exe and dll)
* arm/pe (exe and dll)
* linux/elfamd64
* linux/elfppc32
* mach/elfppc32

- 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.

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