getgid.2

UNIX v6源代码 这几乎是最经典的unix版本 unix操作系统设计和莱昂氏unix源代码分析都是用的该版

.th GETGID II 5/15/74
.sh NAME
getgid  \*-  get group identifications
.sh SYNOPSIS
(getgid = 47.; not in assembler)
.br
.ft B
sys getgid
.ft B
.s3
getgid( )
.ft R
.sh DESCRIPTION
.it Getgid
returns a word (in r0),
the low byte of which contains
the real group ID of
the current process.
The high byte contains the effective group ID
of the current process.
The real group ID identifies the group of the person who is logged in,
in contradistinction to the effective group ID, which
determines his access permission at the moment.
It is thus useful to programs which operate using
the ``set group ID'' mode, to find out who invoked them.
.sh "SEE ALSO"
setgid (II)
.sh DIAGNOSTICS
\*-