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 relevant).
The fourth argument
addr
is the address of a data structure, depending on the command.
The
subcmd
is one of
Q_QUOTAON
Enable quota.
The
addr
argument is the pathname of the file containing
the quota for the file system.
Q_QUOTAOFF
Disable quota.
Q_GETQUOTA
Get limits and current usage of disk space.
The
addr
argument is a pointer to a dqblk structure (defined in
<sys/quota.h>).
Q_SETQUOTA
Set limits and current usage;
addr
is as before.
Q_SETQLIM
Set limits;
addr
is as before.
Q_SETUSE
Set usage.
Q_SYNC
Sync disk copy of a file system's quota.
Q_GETSTATS
Get collected stats.
RETURN VALUE
On success,
quotactl()
returns 0.
On error, -1 is returned, and
errno
is set appropriately.
ERRORS
EACCES
The quota file is not an ordinary file.
EBUSY
Q_QUOTAON
was asked, but quotas were enabled already.
EFAULT
Bad
addr
value.
EINVAL
type
is not a known quota type.
Or,
special
could not be found.
EIO
Cannot read or write the quota file.
EMFILE
Too many open files: cannot open quota file.
ENODEV
special
cannot be found in the mount table.
ENOPKG
The kernel was compiled without quota support.
ENOTBLK
special
is not a block special device.
EPERM
The process was not root (for the file system), and
Q_GETQUOTA
was asked for another
id
than that of the process itself, or anything other than
Q_GETSTATS
or
Q_SYNC
was asked.
ESRCH
Q_GETQUOTA
or
Q_SETQUOTA
or
Q_SETUSE
or
Q_SETQLIM
was asked for a file system that didn't have quota enabled.
This page is part of release 3.14 of the Linux
man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
