$)

$)

The effective gid of this process. If you are on a machine that supports membership in multiple groups simultaneously, gives a space separated list of groups you are in. The first number is the one returned by getegid() , and the subsequent ones by getgroups() , one of which may be the same as the first number.

Similarly, a value assigned to $) must also be a space-separated list of numbers. The first number sets the effective gid, and the rest (if any) are passed to setgroups() . To get the effect of an empty list for setgroups() , just repeat the new effective gid; that is, to force an effective gid of 5 and an effectively empty setgroups() list, say $) = "5 5" .

You can change both the effective gid and the real gid at the same time by using POSIX::setgid() (use only a single numeric argument). Changes to $) require a check to $! to detect any possible errors after an attempted change.

$< , $> , $( and $) can be set only on machines that support the corresponding set[re][ug]id() routine. $( and $) can be swapped only on machines supporting setregid() .

Mnemonic: parentheses are used to group things. The effective gid is the group that's right for you, if you're running setgid.