sh: test: argument expected

[Mike Rovner]

Iván Cabria wrote:

> I am a new user of python. I ran 
> a python script and I got the 
> following message:
> 
> sh: test: argument expected
> 
> I found that this error came from a 
> line in the script:
> energy = atoms.GetPotentialEnergy()

Aparently your python program calls shell script. Without seeing the 
python program it's hard to tell any more.

  > However, I was using the bash shell in the computer

Try (or confirm) that your login script (that you get on the first 
prompt after log in) is bash, not sh. To do that you may say:

     grep your-login-name-here /etc/passwd

and see that line you get ends with :/bin/bash

HTH,
Mike