Running commands

After the compilation and linkage are successful, run the command to see if the result is as expected. If not, figure out the difference of the result or failure. The difference or failure can be in the following areas:

Definition of the standard C variables is different
The definition of the standard C variables could be different for the different operating systems or compilers. Some special handling might be required. For example:
- int is 2 bytes long for DOS but it is 4 bytes long for the z/OS NFS, AIX, and Sun.
- tab has a different value, causing the spacing of the output to be different.
Definition of function calls is slightly different
Although a given function is supported, it might work slightly differently. For example, the "mount table" has a different format in AIX from Sun Solaris.
Library functions might have a defect
Some functions in the C libraries do not function as the documentation describes. You might report the problems or write your own functions to replace them.