from http://nedbatchelder.com/blog/200804/the_structure_of_pyc_files.html

pycat.py

import dis, marshal, struct, sys, time, types

def show_file(fname):
    f = open(fname, "rb")
    magic = f.read(4)
    moddate = f.read(4)
    modtime = time.asctime(time.localtime(struct.unpack('L', moddate)[0]))
    print "magic %s" % (magic.encode('hex'))
    print "moddate %s (%s)" % (moddate.encode('hex'), modtime)
    code = marshal.load(f)
    show_code(code)
     
def show_code(code, indent=''):
    print "%scode" % indent
    indent += '   '
    print "%sargcount %d" % (indent, code.co_argcount)
    print "%snlocals %d" % (indent, code.co_nlocals)
    print "%sstacksize %d" % (indent, code.co_stacksize)
    print "%sflags %04x" % (indent, code.co_flags)
    show_hex("code", code.co_code, indent=indent)
    dis.disassemble(code)
    print "%sconsts" % indent
    for const in code.co_consts:
        if type(const) == types.CodeType:
            show_code(const, indent+'   ')
        else:
            print "   %s%r" % (indent, const)
    print "%snames %r" % (indent, code.co_names)
    print "%svarnames %r" % (indent, code.co_varnames)
    print "%sfreevars %r" % (indent, code.co_freevars)
    print "%scellvars %r" % (indent, code.co_cellvars)
    print "%sfilename %r" % (indent, code.co_filename)
    print "%sname %r" % (indent, code.co_name)
    print "%sfirstlineno %d" % (indent, code.co_firstlineno)
    show_hex("lnotab", code.co_lnotab, indent=indent)
     
def show_hex(label, h, indent):
    h = h.encode('hex')
    if len(h) < 60:
        print "%s%s %s" % (indent, label, h)
    else:
        print "%s%s" % (indent, label)
        for i in range(0, len(h), 60):
            print "%s   %s" % (indent, h[i:i+60])
if __name__ == '__main__':
    show_file(sys.argv[1])