bzexe

bzexe [-c | -d] [-s salt] [-k] [-f] infile [outfile]

-c
    Copy/decompress mode: treats infile as prior bzexe output, strips stub, decompresses to executable (outfile defaults to infile.out).

-d
    Shortcut for -c: decompress bzexe archive back to original executable.

-s salt
    Encrypt output using 16-character salt string for basic protection.

-k
    Keep: preserves original infile after creating outfile (default is delete).

-f
    Force: overwrites existing outfile without prompting.

bzexe is a utility from the bzip2 package that transforms a standard executable into a self-extracting, compressed archive.

It prepends a small bzip2 decompression stub (about 4-5 KB) to the bzip2-compressed executable data. When run, the stub automatically decompresses the payload in memory or to a temp file and executes it seamlessly, passing along all original arguments.

This is ideal for distributing binaries over space-constrained networks, as it reduces file size by 50-70% typically, while maintaining single-file executability without needing separate decompression tools.

Key workflow:
1. Run bzexe infile outfile → produces compressed outfile.
2. User runs outfile directly → auto-decompresses and executes infile contents.

The tool supports encryption via a salt for basic obfuscation. Decompression mode reverts bzexe files back to originals. Note: works best on position-independent executables or those without hard-coded paths; the stub uses execvp() for flexibility.

Linux/Unix focused, portable across similar systems. Compression ratio excels for text-heavy or repetitive binaries.

Stub adds ~5KB overhead; ineffective for already-compressed/large data. May fail on executables with argv[0] path dependencies or non-executable payloads. Not for scripts (use makeself). Encrypted files require exact salt to run.

Stub decompresses to /tmp/bz$$, execs with execvp(), cleans up. Supports ARGV[0] preservation.

bzexe -k myprog myprog.bzexe
Run: ./myprog.bzexe → executes myprog transparently.
Revert: bzexe -c myprog.bzexe myprog

Developed by Julian Seward as part of bzip2 (first release 1996). Included in bzip2 1.0+ distributions for Linux/Unix. Evolved minimally; still in active use for legacy software distribution.

bzip2(1), bunzip2(1), gzip(1), makeself(1)