How to use os.execve in Python

Question

I just started learning Python today and couldn't find a good example online to help me understand os.execve(path, args, env) properly.

How do I use this method (os.execve) to achieve the following task in Python 3.4?
Execute an external command (this command is not some windows command like mkdir, cd... It's a custom command), its location is C:\blah and it takes 5 command line arguments.

Any simpler example of using this command would be much appreciated.

The os.exec* function will stop your program from executing. Is that really what you want? — Winston Ewert, Sep 15 '14 at 12:14
fine how to exexute the external command without stopping my program ? — Dhiwakar Ravikumar, Sep 15 '14 at 12:29
"I just started learning Python today and couldn't find a good example online to help me understand `os.execve(path, args, env)` properly.". Python has a superb online documentation, if you can find it, you are doing something wrong... [Link to os.execve documentation](https://docs.python.org/2/library/os.html#os.execve) — KurzedMetal, Sep 15 '14 at 13:13
@KurzedMetal The os.exec* has a horrible documentation. Which type should the `args` be? What should be the `env`? If the documentation bothered to give an example, perhaps I wouldn't be banging the wall with an `AttributeError: 'str' object has no attribute 'keys'` error right now. — Dr__Soul, Dec 25 '20 at 08:04
UPD. Ok, the following is a working example to execute a python script from python: `os.execv('./myscript.py', ['any_arbitrary_tag', '--my-argument', '--another-argument 42'])` The `env` means the PATH variable of current environment and can be retrieved by `os.environ.get('PATH')` — Dr__Soul, Dec 25 '20 at 08:24

score 3 · Accepted Answer · answered Sep 15 '14 at 12:32

3

You want to use subprocess:

import subprocess
subprocess.check_call(["C:\my program.exe", "all", "my", "args"])

os.exec* replaces the current program with another one. It has is uses, but its usually not what you want.

Note that there are several variants here:

call just calls the program.
check_call calls the program and throws an exception if it fails.
check_output calls the program, throws an exception if it fails, and returns the output of the program.

More advanced use cases can be handled by subprocess.Popen objects.

answered Sep 15 '14 at 12:32

Winston Ewert

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how would this work for a command like " login -u john -ac regular -p password" where login is login.exe ,the command – Dhiwakar Ravikumar Sep 15 '14 at 12:46
`subprocess.call(["login", "-u", "john", "-ac", "regular", "-p", "password"])`. (You may need to pass the full path to login) – Winston Ewert Sep 15 '14 at 12:54
@DhiwakarRavikumar, yes. – Winston Ewert Sep 15 '14 at 13:14
that was stupid to ask I should've tried first. it works on windows as well, is there any simpler way to write this as opposed to the CSV style ? its something that could be improved :) – Dhiwakar Ravikumar Sep 15 '14 at 15:53
@DhiwakarRavikumar, what do you mean by "csv" style? – Winston Ewert Sep 15 '14 at 15:58
I have some commmands that have quite a few arguments and this can get pretty tedious. CSV is Comma Separated Value – Dhiwakar Ravikumar Sep 15 '14 at 16:22
@DhiwakarRavikumar, there are alternatives, look at the subprocess documentation. But passing lists is the recommended way. – Winston Ewert Sep 15 '14 at 16:27
1

The best way to pass multiple arguments is to use [shlex](https://docs.python.org/3/library/shlex.html): `subprocess.call(shlex.split("/path/to/cmd --with --many args -p password"))` – BingsF Aug 14 '15 at 20:42

How to use os.execve in Python

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