sh: test: argument expected

[Iván Cabria]

Hi,

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()

I looked for a solution to this
problem in Internet and I found
(http://www.experts-exchange.com/Oper..._20706303.html)
that the problem was that the variable
was not initialised. I also found
that the bash shell initialises the variables
automatically and the Bourne shell (sh) does not.
(http://www.experts-exchange.com/Oper..._20706303.html)

I suppose that 'sh:' in the error message
means that the script is using the Bourne shell,
and hence, I understand the message error.

However, I was using the bash shell in the computer
I ran the script, not
the Bourne shell (sh). Hence, I do not
understand the 'sh:' in the error message.
Could be that python scripts are using by default the
Bourne shell?

The first line of the python script is:
#!/usr/bin/env python

Thanks in advance.

[Steve Holden]

Iván Cabria wrote:

Hi,

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()

I looked for a solution to this
problem in Internet and I found
(http://www.experts-exchange.com/Oper..._20706303.html)
that the problem was that the variable
was not initialised. I also found
that the bash shell initialises the variables
automatically and the Bourne shell (sh) does not.
(http://www.experts-exchange.com/Oper..._20706303.html)

I suppose that 'sh:' in the error message
means that the script is using the Bourne shell,
and hence, I understand the message error.

However, I was using the bash shell in the computer
I ran the script, not
the Bourne shell (sh). Hence, I do not
understand the 'sh:' in the error message.
Could be that python scripts are using by default the
Bourne shell?

The first line of the python script is:
#!/usr/bin/env python

Thanks in advance.

Question 1: if you run the script using "python scriptname.py" does the
error go away? If so then your script is being executed by the shell and
not by the python interpreter.

Question 2: Are there any blank lines or empty spaces before
#!/usr/bin/env python ?

regards
Steve
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