We've seen how suid works, and sgid works in a similar way. It allows programs to inherit the group ownership of the program rather than that of the current user.

Here's some miscellaneous yet important information about suid and sgid. First, suid and sgid bits occupy the same space as the x bits in a ls -l listing. If the x bit is also set, the respective bits will show up as s (lowercase). However, if the x bit is not set, it will show up as a S (uppercase).

Another important note: suid and suid come in handy in many circumstances, but improper use of these bits can allow the security of a system to be breached. It's best to have as few 'suid' programs as possible. The passwd command is one of the few that must be 'suid'.