<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def sh2(cmd):
 """Execute command in a subshell, return stdout. Stderr is unbuffered from the subshell.x"""

    p = Popen(cmd, stdout=PIPE, shell=True, env=sub_environment())
    out = p.communicate()[0]
    retcode = p.returncode
    if retcode:
        raise CalledProcessError(retcode, cmd)
    else:
        return out.rstrip()