Background
- UID: the ID for each user.
- effective UID: the ID assigned to program. Determine what a process can do and what it cannot
- Set-UID Program: this kind of program has a unique bit set in the file attribute. When this program is executed, it will be granted UID. E.g.
"passwd" has two IDs: eUID = 0, and real ID = 5000 (user's ID). However, For "ls", the eUID = 5000 and real ID = 5000. (ls is not set-UID program)
- How to make a program Set-UID:
chmod 4777 /folder name (4 will enable set-UID)
- How to change the linux
