Alex, I'm not (yet) an experienced sage user, but I have some experience in what you are trying to do, I also tried to write scripts which can be started from the normal shell (with "#!/usr/bin/env sage-python" as a first line, note that sage-python just refers to the python installation that comes with sage) as well as from the sage prompt by sage: load"script.sage" Doing this bears some bitfalls, e.g. note that there are different number types, even for integers, there are the sage 'Integer' and the python 'int' and 'long' types, so if you write a script with a line like a = 3/5 print a and run it from the shell by $ ./script.sage it prints out 0 because '3' and '5' are treated as python int's and not as sage Integer's, so the operator / refers to the python int division which is defined to be an int as well, of course this is not appropriate in an CAS, if you run the same script from the sage prompt sage: load "script.sage" it prints out 3/5 and this result is of type Rational (a sage type, you can prove this by typing "type(_)" at the sage prompt), because sage first wraps this line to a = Integer(3)/Integer(5) and stores it in script.py and the runs this script through python, here / refers to sage division (i.e. division of objects of type Integer). This is a drawback of the genious approach to use python as is, it's confusing for beginners, as a Java dev you should be familiar with operator overloading, in this case 3/5 does not has to be the same as 3/5. So if you want your script to behave the same in both cases you have to write a = Integer(3)/Integer(5) which then wraps to a = Integer(Integer(3))/Integer(Integer(5)) if you run it from the sage prompt, that's actually is no problem, just looks stupid..(maybe a performance issue?) you have the same issue with the operator "^" which normally should refer to exponentiation, but in python means the bitwise operator "xor", exponentiation in python is done by "**", e.g. 2**5, in sage you can use both 2^5 as well as 2**5, so in scripts which you want to run from both, the shell and sage, you have to write 2**5. As far as I know these are the only to cases to consider, in the sage tutorial in section 5 (programing) you can read something about this topics .... Another drawback is as far as I experienced that from a normal script you can't load and compile files with a .spyx ending (tutorial section 5.2 "creating compiled code") by inserting the line load "file.spyx" into your script I hope this helps a bit,... Georg
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