python中的commands模块，执行出错：'{' 不是内部或外部命令，也不是可运行的程序 或批处理文件。

def getstatus(file):
    """Return output of "ls -ld <file>" in a string."""
    import warnings
    warnings.warn("commands.getstatus() is deprecated", DeprecationWarning, 2)
    return getoutput(‘ls -ld‘ + mkarg(file))


# Get the output from a shell command into a string.
# The exit status is ignored; a trailing newline is stripped.
# Assume the command will work with ‘{ ... ; } 2>&1‘ around it..
#
def getoutput(cmd):
    """Return output (stdout or stderr) of executing cmd in a shell."""
    return getstatusoutput(cmd)[1]


# Ditto but preserving the exit status.
# Returns a pair (sts, output)
#
def getstatusoutput(cmd):
    """Return (status, output) of executing cmd in a shell."""
    import os
    pipe = os.popen(‘{ ‘ + cmd + ‘; } 2>&1‘, ‘r‘)
    text = pipe.read()
    sts = pipe.close()
    if sts is None: sts = 0
    if text[-1:] == ‘\n‘: text = text[:-1]
    return sts, text