os.py 文件源码

def _execvpe(file, args, env=None):
    if env is not None:
        func = execve
        argrest = (args, env)
    else:
        func = execv
        argrest = (args,)
        env = environ

    head, tail = path.split(file)
    if head:
        func(file, *argrest)
        return
    if 'PATH' in env:
        envpath = env['PATH']
    else:
        envpath = defpath
    PATH = envpath.split(pathsep)
    saved_exc = None
    saved_tb = None
    for dir in PATH:
        fullname = path.join(dir, file)
        try:
            func(fullname, *argrest)
        except error, e:
            tb = sys.exc_info()[2]
            if (e.errno != errno.ENOENT and e.errno != errno.ENOTDIR
                and saved_exc is None):
                saved_exc = e
                saved_tb = tb
    if saved_exc:
        raise error, saved_exc, saved_tb
    raise error, e, tb

# Change environ to automatically call putenv() if it exists