Testing for non-zero length string in ksh

Issue

• How to check whether the length of the string in the file is zero or non-zero in ksh?

• We have a ksh script that runs PROGRAM1 and writes its exit code to a file.

• We would like to implement a subsequent operation (PROGARM2) being performed after PROGRAM1 only when the file has some non-zero value which represents the exit code of PROGRAM1.

• If the file has zero length value (which means the file is empty), the subsequent operation (PROGRAM2) shouldn't be performed.