.\" Hey Emacs! This file is -*- nroff -*- source.
.\"
.\" Copyright (C) 1996 Andries Brouwer (aeb@cwi.nl)
.\"
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.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" FIXME There is much that is missing and/or out of date in this page.
.\" (There is a quotactl.2 page in the quotactl package that seems to
.\" have more info than this page.)
.\" As things stand the page more or less documents Linux 2.2 reality:
.\"
.\" Linux 2.2 has:
.\"
.\"	Q_GETQUOTA
.\"	Q_GETSTATS
.\"	Q_QUOTAOFF
.\"	Q_QUOTAON
.\"	Q_RSQUASH (not currently documented)
.\"	Q_SETQLIM
.\"	Q_SETQUOTA
.\"	Q_SETUSE
.\"	Q_SYNC
.\"
.\" Linux 2.4 has:
.\"
.\"	Q_COMP_QUOTAOFF
.\"	Q_COMP_QUOTAON
.\"	Q_COMP_SYNC
.\"	Q_GETFMT
.\"	Q_GETINFO
.\"	Q_GETQUOTA
.\"	Q_QUOTAOFF
.\"	Q_QUOTAON
.\"	Q_SETINFO
.\"	Q_SETQUOTA
.\"	Q_SYNC
.\"	Q_V1_GETQUOTA Q_V1_GETSTATS Q_V1_RSQUASH Q_V1_SETQLIM
.\"	Q_V1_SETQUOTA Q_V1_SETUSE
.\"	Q_V2_GETINFO Q_V2_GETQUOTA Q_V2_SETFLAGS Q_V2_SETGRACE
.\"	Q_V2_SETINFO Q_V2_SETQUOTA Q_V2_SETUSE
.\"	Q_XGETQSTAT Q_XGETQUOTA Q_XQUOTAOFF Q_XQUOTAON Q_XQUOTARM
.\"	Q_XSETQLIM
.\"
.\" Linux 2.6.16 has:
.\"
.\"	Q_GETFMT
.\"	Q_GETINFO
.\"	Q_GETQUOTA
.\"	Q_QUOTAOFF
.\"	Q_QUOTAON
.\"	Q_SETINFO
.\"	Q_SETQUOTA
.\"	Q_SYNC
.\"	Q_XGETQSTAT
.\"	Q_XGETQUOTA
.\"	Q_XQUOTAOFF
.\"	Q_XQUOTAON
.\"	Q_XQUOTARM
.\"	Q_XQUOTASYNC
.\"	Q_XSETQLIM
.\"
.TH QUOTACTL 2 2007-06-01 "Linux" "Linux Programmer's Manual"
.SH NAME
quotactl \- manipulate disk quota
.SH SYNOPSIS
.nf
.B #include <sys/types.h>
.br
.B #include <sys/quota.h>
.sp
.BI "int quotactl(int " cmd ", const char *" special ", int " id \
", caddr_t " addr );
.fi
.SH DESCRIPTION
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
.BR quotactl ()
system call manipulates these quota.
Its first argument is
of the form
.BI QCMD( subcmd , type )
where
.I type
is either
.B USRQUOTA
or
.B GRPQUOTA
(for user quota and group quota, respectively), and
.I subcmd
is described below.

The second argument
.I special
is the block special device these quota apply to.
It must be mounted.

The third argument
.I id
is the user or group ID these quota apply to (when relevant).

The fourth argument
.I addr
is the address of a data structure, depending on the command.

The
.I subcmd
is one of
.TP 1.1i
.B Q_QUOTAON
Enable quota.
The
.I addr
argument is the pathname of the file containing
the quota for the file system.
.TP
.B Q_QUOTAOFF
Disable quota.
.TP
.B Q_GETQUOTA
Get limits and current usage of disk space.
The
.I addr
argument is a pointer to a dqblk structure (defined in
.IR <sys/quota.h> ).
.TP
.B Q_SETQUOTA
Set limits and current usage;
.I addr
is as before.
.TP
.B Q_SETQLIM
Set limits;
.I addr
is as before.
.TP
.B Q_SETUSE
Set usage.
.TP
.B Q_SYNC
Sync disk copy of a file system's quota.
.TP
.B Q_GETSTATS
Get collected stats.
.SH "RETURN VALUE"
On success,
.BR quotactl ()
returns 0.
On error, \-1 is returned, and
.I errno
is set appropriately.
.SH ERRORS
.TP 0.9i
.B EACCES
The quota file is not an ordinary file.
.TP
.B EBUSY
.B Q_QUOTAON
was asked, but quotas were enabled already.
.TP
.B EFAULT
Bad
.I addr
value.
.TP
.B EINVAL
.I type
is not a known quota type.
Or,
.I special
could not be found.
.TP
.B EIO
Cannot read or write the quota file.
.TP
.B EMFILE
Too many open files: cannot open quota file.
.TP
.B ENODEV
.I special
cannot be found in the mount table.
.TP
.B ENOPKG
The kernel was compiled without quota support.
.TP
.B ENOTBLK
.I special
is not a block special device.
.TP
.B EPERM
The process was not root (for the file system), and
.B Q_GETQUOTA
was asked for another
.I id
than that of the process itself, or anything other than
.B Q_GETSTATS
or
.B Q_SYNC
was asked.
.TP
.B ESRCH
.B Q_GETQUOTA
or
.B Q_SETQUOTA
or
.B Q_SETUSE
or
.B Q_SETQLIM
was asked for a file system that didn't have quota enabled.
.SH "CONFORMING TO"
BSD.
.SH "SEE ALSO"
.BR quota (1),
.BR getrlimit (2),
.BR setrlimit (2),
.BR ulimit (3),
.BR quotacheck (8),
.BR quotaon (8)