User id and Group id in Linux

Kindly guide me to the tutorials where i could find information on User id (Real and Effective) and Group id (Real and Effective) with开发者_StackOverflow reference to Linux.

Thanks,LinuxPenseur

try this: http://www.cyberciti.biz/tips/linux-more-on-user-id-password-and-group-management.html

This is a surprisingly complicated question. For starters, you are forgetting about the Saved UID. I don't have an answer, but can give you some links for research:

• http://www.imodulo.com/gnu/glibc/Users-and-Groups.html
• http://www.stanford.edu/~stinson/cs155/notes/setuid.txt
• http://linux.die.net/man/2/setresuid