List of Terms

digest

a collection of new messages mailed to the members of an archived list as one message. A list is called digested when it is archived and, periodically, a digest is sent out.

Group ID

(GID)

an identification number assigned to files, directories, and processes to restrict access--similar to UID except multiple people can be a member of a group. On Unix-type systems, groups can be set up (defined in the /etc/group file). When a user name is a member of a group, she can access files created with that GID (assuming permissions allow it).

Mail Transfer Agent

(MTA)

a program, such as Sendmail, responsible for passing mail from one location to another.

Set Group ID

(SGID)

a file attribute which allows a program to run with specific group privileges no matter who executes it.

smrsh

(SendMail Restricted SHell) the shell that Sendmail uses to execute programs. smrsh puts restrictions on the programs that can be run to make it safer than using a regular shell such as the Bourne Shell.

Set User ID

(SUID)

a file attribute which allows a program to run as a specific user no matter who executes it.

User ID

(UID)

an identification number assigned to files directories, and processes--similar to GID except every user has a unique UID. Every process must run under a UID (the one-to-one relationship between the UID and user name is defined in /etc/passwd). The process' UID determines what the program can access. In general a regular user can change the permissions on files that she owns unless the UID is 0 (the root user). In that case, root can modify any files on the system.

wrapper

a program used to start another program; usually a wrapper is SUID or SGID so it can bestow privileges onto another program that the other program would not normally have.