FORTRAN in UNIX

[ye qi]

Hi, 
Please excuse me if you think this net is an appropriate place to post the 
following question.

I am working on a fortran program under SPARCompiler environment.  I want to
use a system call in which the parameter is a variable.  For example:

      call ('uncompress filename') 

where filename is variable whose value is assigned in a previous statement. 
This doesn't work. However, it is ok when I replace variable filename with an 
actual file name.  Could anyone tell how to use system call in which the 
parameter is a variable.

Thank you very much.

Ye Qi