Example: using different input files
This example shows that you can use the same COBOL program to access different files by setting an environment variable before the programs runs.
Consider a COBOL program that contains the following SELECT
clause:
SELECT MAINFILE ASSIGN TO MAINA
Suppose you want the program to access either the checking
or
savings
file using the file called MAINFILE
within the program. To do so, set the MAINA environment variable before the
program runs by using one of the following two statements as appropriate, assuming that the
checking
and savings
files are in the /accounts
directory:
export MAINA=/accounts/checking
export MAINA=/accounts/savings
You can thus use the same program to access either the checking
or
savings
file as the file called MAINFILE
within the program without having to change or recompile the source.