Error executing python scripts

Question

When I try to execute a python script with arguments, the script fails and show the following error:

-bash: syntax error near unexpected token `"Lary",'

I try to execute the script like this:

display("Lary", 43, "M")

My code

#! /usr/bin/python
def display(name, age, sex):
 print "Name: ", name
 print "Age: ", age
 print "Sex: ", sex

I try setting execute rights to the script (chmod 755 test.py) and I always get the same error.

What is wrong?

• Bharat: Can you show your whole code including where you call display("Lary", 43, "M"). And does the script work when you invoke it by doing python test.py ?
• Bharat: And are you sure your python executable is at /usr/bin/ ?
• Paulo Scardine: try a shebang like #!/usr/bin/env python
• Tom Dalton: I think the comment above should read #!/usr/bin/env python
• Paulo Scardine: You have to place display("Lary", 43, "M") inside the script and call it like ./script_name.py. I guess bash is complaining because you are trying to use Python syntax on the command prompt.

Answer 1

If I understand correctly, you want to run something like:

 ./test.py "Lary" 43 "M"

from the command line. To do this, you set the permissions correctly. But you need to access the command line arguments using the sys module:

 #! /usr/bin/python
 import sys
 def display(name, age, sex):
 print "Name: ", name
 print "Age: ", age
 print "Sex: ", sex
 display(sys.argv[1],sys.argv[2],sys.argv[3])

sys.argv returns a list of the command line arguments with the name of the file being sys.argv[0] (in this case ./test.py). Of course, you should probably have some sort of argument checking making sure there are enough arguments, etc. Also, make sure to parse the commands correctly. For example, if age is supposed to be an integer, you need to do age = int(sys.argv[2]) as sys.argv is a list of strings, as is standard in most languages.

Answer 2

That error message means you're calling your function from the bash shell:

dsm@winter:~/coding$ display("Lary", 43, "M")
bash: syntax error near unexpected token `"Lary",'

You need to call it from the Python console:

dsm@winter:~/coding$ python -i display.py
>>> display("Larry", 43, "M")
Name: Larry
Age: 43
Sex: M

You can't really call Python functions from the bash console the way you're trying.

Answer 3

If you want to pass arguments to a python program, the simplest way is with sys.argv:

my_program.py:

#!/usr/bin/env python
import sys
print "Arguments passed:"
print sys.argv

Then run your program like:

./my_program.py this is "A test" 1 2 3

Answer 4

You do not execute a script calling the function display("Lary", 43, "M")

you use python my_script.py from bash or ./my_script.py

You are getting a bash error not a python error, to make a python script executable you just need chmod +x my_script.py.

~$ display("Lary", 43, "M")
bash: syntax error near unexpected token `"Lary",'

my_script.py:

import sys
def display(name, age, sex):
 print "Name: ", name
 print "Age: ", age
 print "Sex: ", sex
name = sys.argv[1]
age = sys.argv[2]
sex = sys.argv[3]
display(name, age, sex)
~$ python my_script.py foo 43 male
Name: foo
Age: 43
Sex: male