Execute Commands Sequentially in Python?

Question

I would like to execute multiple commands in a row:

i.e. (just to illustrate my need):

cmd (the shell)

then

cd dir

and

ls

and read the result of the ls.

Any idea with subprocess module?

Update:

cd dir and ls are just an example. I need to run complex commands (following a particular order, without any pipelining). In fact, I would like one subprocess shell and the ability to launch many commands on it.

Answer 1

To do that, you would have to:

• supply the shell=True argument in the subprocess.Popen call, and
• separate the commands with:
  • ; if running under a *nix shell (bash, ash, sh, ksh, csh, tcsh, zsh etc)
  • & if running under the cmd.exe of Windows

Answer 2

There is an easy way to execute a sequence of commands.

Use the following in subprocess.Popen

"command1; command2; command3" 

Or, if you're stuck with windows, you have several choices.

• Create a temporary ".BAT" file, and provide this to subprocess.Popen

• Create a sequence of commands with "\n" separators in a single long string.

Use """s, like this.

""" command1 command2 command3 """ 

Or, if you must do things piecemeal, you have to do something like this.

class Command( object ):     def __init__( self, text ):         self.text = text     def execute( self ):         self.proc= subprocess.Popen( ... self.text ... )         self.proc.wait()  class CommandSequence( Command ):     def __init__( self, *steps ):         self.steps = steps     def execute( self ):         for s in self.steps:             s.execute() 

That will allow you to build a sequence of commands.