The quota system defines for each user and/or group a soft limit and a hard
limit bounding the amount of disk space that can be used on a given file
system. The hard limit cannot be crossed. The soft limit can be crossed, but
warnings will ensue. Moreover, the user cannot be above the soft limit for
more than one week (by default) at a time: after this week the soft limit
counts as hard limit.
The quotactl system call manipulates these quota. Its first argument is
of the form QCMD(subcmd,type) where
type is either USRQUOTA or GRPQUOTA (for user quota and
group quota, respectively), and subcmd is described below.
The second argument special is the block special device these quota apply
to. It must be mounted.
The third argument id is the user or group ID these quota apply to (when
The fourth argument addr is the address of a data structure, depending on
The subcmd is one of
Enable quota. The addr argument is the pathname of
the file containing the quota for the filesystem.
Get limits and current usage of disk space. The addr
argument is a pointer to a dqblk structure (defined in