NAME

Quota - Perl interface to file system quotas

SYNOPSIS

    use Quota;

    ($block_curr, $block_soft, $block_hard, $block_timelimit,
     $inode_curr, $inode_soft, $inode_hard, $inode_timelimit) =
    Quota::query($dev [,$uid [,isgrp]]);

    ($block_curr, $block_soft, $block_hard, $block_timelimit,
     $inode_curr, $inode_soft, $inode_hard, $inode_timelimit) =
    Quota::rpcquery($host, $path [,$uid]);

    Quota::setqlim($dev, $uid, $block_soft, $block_hard,
		   $inode_soft, $inode_hard [,$tlo [,isgrp]]);

    Quota::sync([$dev]);

    $arg = Quota::getqcarg([$path]);

    Quota::setmntent();
    ($dev, $path, $type, $opts) = Quota::getmntent();
    Quota::endmntent();

DESCRIPTION

The Quota module provides access to file system quotas. The quotactl system call or ioctl is used to query or set quotas on the local host, or queries are submitted via RPC to a remote host. Mount tables can be parsed with getmntent and paths can be translated to device files (or whatever the actual quotactl implementations needs as argument) of the according file system.

Functions

($bc,$bs,$bh,$bt, $ic,$is,$ih,$it) = Quota::query($dev, $uid, $isgrp)

Get current usage and quota limits for a given file system and user. The user is specified by its numeric uid; defaults to the process' real uid.

The type of $dev varies from system to system. It's the argument which is used by the quotactl implementation to address a specific file system. It may be the path of a device file (e.g. /dev/sd0a) or the path of the mount point or the quotas file at the top of the file system (e.g. /home.stand/quotas). However you do not have to worry about that; use Quota::getqcarg to automatically translate any path inside a file system to the required $dev argument.

$dev may also be in the form of hostname:path, which has the module transparently query the given host via a remote procedure call (RPC). In case you have NFS (or similar network mounts), this type of argument may also be produced by Quota::getqcarg. Note: RPC queries require rquotad(1m) to be running on the target system. If the daemon or host are down, the timeout is 12 seconds.

In $bc and $ic the current usage in blocks and inodes is returned. $bs and $is are the soft limits, $bh and $ih hard limits. If the soft limit is exceeded, writes by this user will fail for blocks or inodes after $bt or $it is reached. These times are expressed as usual, i.e. in elapsed seconds since 00:00 1/Jan/1970 GMT.

Note: When the quota limits are not exceeded, the timestamps are meaningless and should be ignored. When hard and soft limits are zero, there is no limit for that user. On most systems Quota::query will return undef in that case and errno will be set to ESRCH.

When $isgrp is given and set to 1, $uid is taken as gid and group quotas are queried. This is not supported across RPC and even locally only on a few architectures (e.g. Linux and other BSD based Unix variants, OSF/1 and AIX - check the quotactl(2) man page on your systems). If unsupported, this flag is ignored.

Quota::setqlim($dev, $uid, $bs,$bh, $is,$ih, $tlo, $isgrp)

Sets quota limits for the given user. Meanings of $dev, $uid, $bs, $bh, $is and $ih are the same as in Quota::query.

$tlo decides how the time limits are initialized: 0: The time limits are set to NOT STARTED, i.e. the time limits are not initialized until the first write attempt by this user. This is the default. 1: The time limits are set to 7.0 days. More alternatives (i.e. setting a specific time) aren't available in most implementations.

When $isgrp is given and set to 1, $uid is taken as gid and group quota limits are set. This is supported only on a few architectures (see above). If unsupported, this flag is ignored.

Note: if you want to set the quota of a particular user to zero, i.e. no write permission, you must not set all limits to zero, since that is equivalent to unlimited access. Instead set only the hard limit to 0 and the soft limit for example to 1.

Note that you cannot set quotas via RPC.

Quota::sync($dev)

Have the kernel update the quota file on disk or all quota files if no argument given (the latter doesn't work on all systems, in particular on HP-UX 10.10).

The main purpose of this function is to check if quota is enabled in the kernel and for a particular file system. Read the quotaon(1m) man page on how to enable quotas on a file system.

Note: on some systems this function always returns a success indication, even on partitions which do not have quotas enabled (e.g. Linux 2.4). This is not a bug in this module; it's a limitation in certain kernels.

($bc,$bs,$bh,$bt, $ic,$is,$ih,$it) =

Quota::rpcquery($host,$path,$uid)

This is equivalent to Quota::query("$host:$path",$uid), i.e. query quota for a given user on a given remote host via RPC. $path is the path of any file or directory inside the wanted file system on the remote host.

$arg = Quota::getqcarg($path)

Get the required $dev argument for Quota::query and Quota::setqlim for the file system you want to operate on. $path is any path of an existing file or directory inside that file system. The path argument is optional and defaults to the current working directory.

The type of $dev varies between operating systems, i.e. different implementations of the quotactl functionality. Hence it's important for compatibility to always use this module function and not really pass a device file to Quota::query (as returned by Quota::getdev). See also above at Quota::query

$dev = Quota::getdev($path)

Returns the device entry in the mount table for a particular file system, specified by any path of an existing file or directory inside it. $path defaults to the working directory. This device entry need not really be a device. For example on network mounts (NFS) it's "host:mountpath", with amd(1m) it may be something completely different.

NEVER use this to produce a $dev argument for other functions of this module, since it's not compatible. On some systems quotactl does not work on devices but on the quotas file or some other kind of argument. Always use Quota::getqcarg.

Quota::setmntent()

Opens or resets the mount table. This is required before the first invocation of Quota::getmntent.

Note: on some systems there is no equivalent function in the C library. But you still have to call this module procedure for initialization of module-internal variables.

($dev, $path, $type, $opts) = Quota::getmntent()

Returns the next entry in the system mount table. This table contains information about all currently mounted (local or remote) file systems. The format and location of this table (e.g. /etc/mtab) vary from system to system. This function is provided as a compatible way to parse it. (On some systems, like OSF/1, this table isn't accessible as a file at all, i.e. only via Quota::getmntent).

Quota::endmntent()

Close the mount table. Should be called after the last use of Quota::getmntent to free possibly allocated file handles and memory. Always returns undef.

Quota::strerr()

Translates $! to a quota-specific error text. You should always use this function to output error messages, since the normal messages don't always make sense for quota errors (e.g. ESRCH: No such process, here: No quota for this user)

Note that this function only returns a defined result if you called a Quota command directly before which returned an error indication.

RETURN VALUES

Functions that are supposed return lists or scalars, return undef upon errors. As usual $! contains the error code (see Quota::strerr).

Quota::endmntent always returns undef. All other functions return 0 upon success, non-zero integer otherwise.

EXAMPLES

An example for each function can be found in the test script test.pl. See also the contrib directory, which contains some longer scripts, kindly donated by users of the module.

BUGS

With remote quotas we have to rely on the remote system to state correctly which block size the quota values are referring to. Old versions of the Linux rpc.rquotad reported a block size of 4 kilobytes, which was wildly incorrect. For more info on this and other Linux bugs please see INSTALL.

AUTHORS

This module was created 1995 by Tom Zoerner (email: tomzo AT nefkom DOT net) and since then continually improved and ported to many operating- and file-systems. Numerous people have contributed to this process; for a complete list of names please see the CHANGES document.

SEE ALSO

perl(1), edquota(1m), quotactl(2) or quotactl(7I), mount(1m), mtab(4) or mnttab(4), quotaon(1m), setmntent(3), getmntent(3) or getmntinfo(3), endmntent(3), rpc(3), rquotad(1m).