When I have searched for the header unistd.h, in The Open Group, I found that it contains the standard symbolic constants & types and for sys/types.h it said for data types.
Then I found that both have uid_t, pid_t and several similar types.
I am confused why they have divided so and what are the differences between them. I have googled but I didn't get a satisfactory answers.
I will be thankful if some one can give me detailed explanation.
Thank you.