Switch user ID (UNIX)
su [-c] [[-] userid [arguments]]
The su utility lets you temporarily become another user, then return to your regular userid.
The su utility requests the password of the given userid (root, by default) and changes to that userid, invoking its shell but modifying only essential elements of the environment. Only the HOME, PATH, and possibly SHELL environment variables are changed, but the new shell has the rights and privileges of the user specified. The new userid remains in effect until this shell exits.
|This utility needs to have the setuid (“set user ID”) bit set in its permissions. If you use mkefs, mketfs, or mkifs on a Windows host to include this utility in an image, use the perms attribute to specify its permissions explicitly, and the uid and gid attributes to set the ownership correctly.|
Logging In, Logging Out, and Shutting Down in the Neutrino User's Guide