UPX(1) UPX(1) (NAME) upx - (SYNOPSIS) upx [ command ] [ options ] filename... (ABSTRACT) The Ultimate Packer for eXecutables Copyright (c) 1996-2026 Markus Oberhumer, Laszlo Molnar & John Reiser https://upx.github.io UPX . (decompression) ** . ..SH " (DISCLAIMER)" UPX COPYING . . . (SECURITY CONTEXT) : UPX . . UPX ! (DESCRIPTION) UPX : - : UPX / UPX - : Zip UPX ! - : - (in-place decompression) - : . . - : UPX DLL Windows macOS Linux - : UPX C++ (endian-neutral) - : - : UPX (GNU General Public License v2+) UPX <<>> . (COMMANDS) (Compress) upx yourfile.exe . (Decompress) UPX -d upx -d yourfile.exe . (Test) -t upx -t yourfile.exe . . . (List) -l upx -l yourfile.exe / yourfile.exe . (OPTIONS) -q: -q -q ( -qq): -q -q -q ( -qqq): --help: --version: UPX --exact: -d . [: . - - .] -k: -o file: file [ ... ... - `upx --help' ].SH " (COMPRESSION LEVELS & TUNING)" UPX -1 -9 --best . 512 KiB -8 -7 . o . o / . o . o --best . --best . : o upx --brute --no-lzma myfile.exe upx --ultra-brute --no-lzma myfile.exe . o --lzma LZMA * * . . ( --lzma --all-methods --brute --no-lzma .) o --overlay=strip . o win32/pe --strip-relocs=0 . . (OVERLAY HANDLING OPTIONS) : <<>> (overlay) ( ). UPX : . . --overlay=copy . [] --overlay=strip . : . --overlay=skip . (ENVIRONMENT VARIABLE) UPX UPX . . : DOS/Windows: set UPX=-9 --compress-icons#0 sh/ksh/zsh: UPX="-9 --compress-icons=0"; export UPX csh/tcsh: setenv UPX "-9 --compress-icons=0" DOS/Windows COMMAND.COM '=' '#' . - UPX . --no-env . (NOTES FOR THE SUPPORTED EXECUTABLE FORMATS) ATARI/TOS (NOTES FOR ATARI/TOS) Atari ST/TT Motorola 68000 . :-). https://freemint.github.io . . (debug) . : --all-methods . . vmlinuz/i386. DOS/COM (NOTES FOR DOS/COM) UPX ( Win95/98/ME ) . +286 . . : ~65100 . : --8086 8086 . --all-methods . . --all-filters . . DOS/EXE (NOTES FOR DOS/EXE) dos/exe <<>> - DOS . UPX ( Win95/98/ME ) . +286 . : --8086 8086 . --no-reloc (relocation) exe. --all-methods . . DOS/SYS (NOTES FOR DOS/SYS) +286 . . : ~65350 . : --8086 8086 . --all-methods . . --all-filters . . DJGPP2/COFF (NOTES FOR DJGPP2/COFF) ** strip UPX . strip (stub) () . UPX / strip v2.8.x : 4 KiB . UPX stubify . COFF stubify . --coff ( ). UPX packfile Allegro . DLM ( ) . . . : --coff COFF EXE. UPX (stub) . --all-methods . . --all-filters . . Linux/386 UPX : ELF ("linux/elf386") ("linux/sh386") ("linux/386"). . - vmlinuz/386 . ``'' ( CD-ROM EPROM ) ``'' ( RAM swap /tmp ) . (CPU) . . (CPU overhead) I/O . RAM swap /tmp . I/O . (Paging) swap /tmp . ``'' / / . . UPX . . UPX RAM . RAM / swap . (bash csh ) `make' . UPX Linux : Linux/elf386 Linux/sh386 Linux/386. Linux/386 . (stub) UPX /tmp () . ELF Linux/elf386 UPX RAM exec /tmp /proc . ``-c'' Linux/sh386 . UPX ``-c'' . : - UPX AOUT ELF libc4 libc5 libc6 Shell/Perl/Python/... .class ... . - (self-contained) . . - UPX . gzip UPX . [ UPX (checksum) . ] - (stub) syscall libc ELF . - FreeBSD Linux . [ ] : - ( `sh' `make') . - `ldd' `size' (stub) . 0.82 UPX `size' . patches/patch-elfcode.h `size' GNU BFD . : - UPX strip . - (platform independence) - NFS . - suid guid sticky-bit . - suid . - UPX . Perl __DATA__ . - exitcode 127 . . `strace -o strace.log compressed_file' . . linux/elf386 RAM exec /tmp /proc . linux/elf386 Linux ELF . . : ELF UPX exec() PT_INTERP ( ) . brk() PT_LOAD . UPX Elf_auxv ( /lib/ld-linux.so ) e_entry . (stub) UPX syscall . libc . : - linux/elf386 linux/sh386 RAM swap . swap . << >> (out of memory) . malloc() 0 . (kill) . /usr/bin/top swap . : () LINUX/SH386 (NOTES FOR LINUX/SH386) . "-c" Linux/sh386 . UPX "-c" . /tmp /proc . Linux/sh386 . . : ( "#!/" "#! /" ) "-c " UPX ( PT_INTERP ) "-c" . : sh ash bash bsh csh ksh tcsh pdksh. : UPX (: "#! /bin/sh option3\n".) (stub) UPX syscall . libc . : - linux/elf386 linux/sh386 RAM swap . swap . << >> (out of memory) . malloc() 0 . (kill) . /usr/bin/top swap . : () . linux/386 /tmp /proc . execve() . linux/386 linux/elf386 linux/sh386 . . : ELF <<-c>> UPX execve() . - - . UPX stub overlay . UPX stub ELF (statically linked) : ) overlay /tmp ) ) (execve) /tmp /proc//fd/X ) (fork) /tmp UPX stub . libc . : - /tmp . . - /proc stub /proc//exe /proc//fd/X . (mount) /proc . - `top' . execve ( /proc//fd/3 ) . - . emacs ( :-)) . : --force-execve "execve" linux/386 linux/elf386 linux/sh386 . PS1/EXE (NOTES FOR PS1/EXE) Sony PlayStation (PSone) MIPS R3000 . Atari . . : / (MiB). : - UPX CD-Mastering . CD-Master "--boot-only" . upx Sony PlayStation (PSone) Sony PlayStation 2 (PS2, PStwo) Sony PlayStation Portable (PSP) . - . UPX 'packed data overlap' . "--force" UPX (relocate) . : --all-methods . . --8-bit [: ] --8mib-ram PSone RAM [: ] --boot-only CD-Mastering ! ! --no-align CD mode 2 . CD . ! win32/pe. TMT/ADAM (NOTES FOR TMT/ADAM) TMT Pascal - http://www.tmt.com . : --all-methods . . --all-filters . . VMLINUZ/386 (NOTES FOR VMLINUZ/386) vmlinuz/386 bvmlinuz/386 gzip ("vmlinuz" "zImage" "bzImage") UPX . vmlinuz/386 . : - "vmlinuz/386" "bvmlinuz/386" - . : - ( ). . 2.2.16 : 1589708 vmlinux 641073 bzImage [] 560755 bzImage.upx [ "upx -9"] - ( ). : () : --all-methods . . --all-filters . . WATCOM/LE (NOTES FOR WATCOM/LE) UPX (extenders) : DOS4G, DOS4GW, PMODE/W, DOS32a, CauseWay. WDOS/X ( BUGS ). DLL LX . : --le LE (unbound) (stub) . PE UPX . UPX ( ) . . . . DLL DLL UPX . msvcrt.dll dll . ".scr" ( exe ). PE UPX ( 10 - 30 KiB) "-i" . : --compress-exports=0 export . Wine . --compress-exports=1 export . [] export ( winword.exe) . UPX export DLL . --compress-icons=0 . --compress-icons=1 . --compress-icons=2 . [] --compress-icons=3 . --compress-resources=0 (resource) . --keep-resource=list . . : I. I . . I . : --keep-resource=2/MYBITMAP,5,6/12345 UPX "MYBITMAP" (5) 12345 . --force . . --strip-relocs=0 relocation . --strip-relocs=1 relocation . [] 0x400000 . . Windows 3.x (Win32s) . UPX relocation DLL . --all-methods . . --all-filters . . 0 1 2 . UPX . (BUGS) . (AUTHORS) Markus F.X.J. Oberhumer http://www.oberhumer.com Laszlo Molnar John F. Reiser (COPYRIGHT) Copyright (C) 1996-2026 Markus Franz Xaver Johannes Oberhumer Copyright (C) 1996-2026 Laszlo Molnar Copyright (C) 2000-2026 John F. Reiser UPX GNU General Public License v2+ GPLv2+ ( COPYING ) ( ) GPLv+2 ( LICENSE ). . UPX COPYING LICENSE . UPX . upx 5.2.0 2026-06-08 UPX(1)