File::ExtAttr(3pm)

1File::ExtAttr(3)      User Contributed Perl Documentation     File::ExtAttr(3)
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NAME

6       File::ExtAttr - Perl extension for accessing extended attributes of
7       files
8

SYNOPSIS

10         use File::ExtAttr ':all';
11         use IO::File;
12
13         # Manipulate the extended attributes of files.
14         setfattr('foo.txt', 'colour', 'red') || die;
15         my $colour = getfattr('bar.txt', 'colour');
16         if (defined($colour))
17         {
18             print $colour;
19             delfattr('bar.txt', 'colour');
20         }
21
22         # Manipulate the extended attributes of a file via a file handle.
23         my $fh = new IO::File('<foo.txt') || die;
24         setfattr($fh, 'colour', 'red') || die;
25
26         $fh = new IO::File('<bar.txt') || die;
27         $colour = getfattr($fh, 'colour');
28         if (defined($colour))
29         {
30             print $colour;
31             delfattr($fh, 'colour');
32         }
33
34         # List attributes in the default namespace.
35         print "Attributes of bar.txt:\n";
36         foreach (listfattr($fh))
37         {
38           print "\t$_\n";
39         }
40
41         # Examine attributes in a namespace-aware manner.
42         my @namespaces = listfattrns($fh);
43
44         foreach my $ns (@namespaces)
45         {
46           print "Attributes in namespace '$ns': ";
47           my @attrs = listfattr($fh, { namespace => $ns });
48           print join(',', @attrs)."\n";
49         }
50

DESCRIPTION

52       File::ExtAttr is a Perl module providing access to the extended
53       attributes of files.
54
55       Extended attributes are metadata associated with a file.  Examples are
56       access control lists (ACLs) and other security parameters.  But users
57       can add their own key=value pairs.
58
59       Extended attributes may not be supported by your operating system.
60       This module is aimed at Linux, Unix or Unix-like operating systems
61       (e.g.: Mac OS X, FreeBSD, NetBSD, Solaris).
62
63       Extended attributes may also not be supported by your filesystem or
64       require special options to be enabled for a particular filesystem.
65       E.g.:
66
67         mount -o user_xattr /dev/hda1 /some/path
68
69   Supported OSes
70       Linux
71       Mac OS X
72       FreeBSD 5.0 and later
73       NetBSD 4.0 and later
74       Solaris 10 and later
75
76   Unsupported OSes
77       OpenBSD
78
79   Namespaces
80       Some implementations of extended attributes support namespacing.  In
81       those implementations, the attribute is referred to by namespace and
82       attribute name.
83
84       Linux
85           The primary namespaces are "user" for user programs; "security",
86           "system" and "trusted" for file security/access-control.  See
87           <http://www.die.net/doc/linux/man/man5/attr.5.html> for more
88           details.
89
90           Namespaces on Linux are described by a string, but only certain
91           values are supported by filesystems. In general "user", "security",
92           "system" and "trusted" are supported, by others may be supported --
93           e.g.: "os2" on JFS. File::Extattr will be able to access any of
94           these.
95
96       FreeBSD, NetBSD
97           *BSD have two namespaces: "user" and "system".
98
99           Namespaces on *BSD are described by an integer. File::ExtAttr will
100           only be able to access attributes in "user" and "system".
101
102       Mac OS X
103           OS X has no support for namespaces.
104
105       Solaris
106           Solaris has no support for namespaces.
107
108   Flags
109       The functions take a hash reference as their final parameter, which can
110       specify flags to modify the behaviour of the functions.  The flags
111       specific to a function are documented in the function's description.
112
113       All functions support a "namespace" flag. E.g.:
114
115         use File::ExtAttr ':all';
116         use IO::File;
117
118         # Manipulate the extended attributes of files.
119         setfattr('foo.txt', 'colour', 'red') || die;
120         my $colour = getfattr('bar.txt', 'colour', { namespace => 'user');
121
122       If no namespace is specified, the default namespace will be used.  On
123       Linux and *BSD the default namespace will be "user".
124

METHODS

126       getfattr([$filename | $filehandle], $attrname, [\%flags])
127           Return the value of the attribute named $attrname for the file
128           named $filename or referenced by the open filehandle $filehandle
129           (which should be an IO::Handle or subclass thereof).
130
131           If no attribute is found, returns "undef". Otherwise gives a
132           warning.
133
134       setfattr([$filename | $filehandle], $attrname, $attrval, [\%flags])
135           Set the attribute named $attrname with the value $attrval for the
136           file named $filename or referenced by the open filehandle
137           $filehandle (which should be an IO::Handle or subclass thereof).
138
139           %flags allows control of whether the attribute should be created or
140           should replace an existing attribute's value. If the key "create"
141           is true, setfattr will fail if the attribute already exists. If the
142           key "replace" is true, setfattr will fail if the attribute does not
143           already exist. If neither is specified, then the attribute will be
144           created (if necessary) or silently replaced.
145
146           If the attribute could not be set, a warning is issued.
147
148           Note that "create" cannot be implemented in a race-free manner on
149           *BSD.  If your code relies on the "create" behaviour, it may be
150           insecure on *BSD.
151
152       delfattr([$filename | $filehandle], $attrname, [\%flags])
153           Delete the attribute named $attrname for the file named $filename
154           or referenced by the open filehandle $filehandle (which should be
155           an IO::Handle or subclass thereof).
156
157           Returns true on success, otherwise false and a warning is issued.
158
159       listfattr([$filename | $filehandle], [\%flags])
160           Return an array of the attributes on the file named $filename or
161           referenced by the open filehandle $filehandle (which should be an
162           IO::Handle or subclass thereof).
163
164           Returns undef on failure and $! will be set.
165
166       listfattrns([$filename | $filehandle], [\%flags])
167           Return an array containing the namespaces of attributes on the file
168           named $filename or referenced by the open filehandle $filehandle
169           (which should be an IO::Handle or subclass thereof).
170
171           Returns undef on failure and $! will be set.
172

EXPORT

174       None by default.
175
176       You can request that "getfattr", "setfattr", "delfattr" and "listfattr"
177       be exported using the tag ":all".
178
179   Exportable constants
180       None
181

BUGS

183       You cannot set empty attributes on Mac OS X 10.4 and earlier.  This is
184       a bug in Darwin, rather than File::ExtAttr.
185

187       The latest version of this software should be available from its home
188       page: <http://sourceforge.net/projects/file-extattr/>
189
190       OS2::ExtAttr provides access to extended attributes on OS/2.
191
192       Eiciel, <http://rofi.pinchito.com/eiciel/>, is an access control list
193       (ACL) editor for GNOME; the ACLs are stored in extended attributes.
194
195       Various low-level APIs exist for manipulating extended attributes:
196
197       Linux
198           getattr(2), attr(5)
199
200           <http://www.die.net/doc/linux/man/man2/getxattr.2.html>
201
202           <http://www.die.net/doc/linux/man/man5/attr.5.html>
203
204       OpenBSD
205           OpenBSD 3.7 supported extended attributes, although support was
206           never built into the default GENERIC kernel. Its support was
207           documented in the "extattr" man page:
208
209           <http://www.openbsd.org/cgi-bin/man.cgi?query=extattr_get_file&apropos=0&sektion=0&manpath=OpenBSD+Current&arch=i386&format=html>
210
211           Support was removed in OpenBSD 3.8 -- see the CVS history for the
212           include file "sys/extattr.h".
213
214           <http://www.openbsd.org/cgi-bin/cvsweb/src/sys/sys/Attic/extattr.h>
215
216       FreeBSD
217           FreeBSD >= 5.0 supports extended attributes.
218
219           extattr(2)
220
221           <http://www.freebsd.org/cgi/man.cgi?query=extattr&sektion=2&apropos=0&manpath=FreeBSD+6.0-RELEASE+and+Ports>
222
223       NetBSD
224           NetBSD >= 3.0 supports extended attributes, but you'll need to use
225           NetBSD >= 4.0 to get UFS filesystem support for them.
226
227           <http://netbsd.gw.com/cgi-bin/man-cgi?extattr_get_file+2+NetBSD-current>
228
229           <http://www.netbsd.org/Changes/changes-4.0.html#ufs>
230
231       Mac OS X
232           getxattr(2)
233
234           <http://developer.apple.com/documentation/Darwin/Reference/ManPages/man2/getxattr.2.html>
235
236           <http://arstechnica.com/reviews/os/macosx-10.4.ars/7>
237
238       Solaris
239           attropen(3C), fsattr(5)
240
241           <http://docsun.cites.uiuc.edu/sun_docs/C/solaris_9/SUNWaman/hman3c/attropen.3c.html>
242
243           <http://docsun.cites.uiuc.edu/sun_docs/C/solaris_9/SUNWaman/hman5/fsattr.5.html>
244
245           Solaris also has extensible system attributes, which are used by
246           Solaris's CIFS support on ZFS, and have a confusingly similar name
247           to extended file attributes. These system attributes are stored in
248           extended file attributes called SUNWattr_ro and SUNWattr_rw.  See
249           PSARC 2007/315 for more details:
250
251           <http://opensolaris.org/os/community/arc/caselog/2007/315/spec-final-txt/>
252

AUTHOR

254       Kevin M. Goess, <kgoess@ensenda.com>
255
256       Richard Dawe, <richdawe@cpan.org>
257

COPYRIGHT AND LICENSE

259       Copyright (C) 2005 by Kevin M. Goess
260
261       Copyright (C) 2005, 2006, 2007, 2008 by Richard Dawe
262
263       This library is free software; you can redistribute it and/or modify it
264       under the same terms as Perl itself, either Perl version 5.8.5 or, at
265       your option, any later version of Perl 5 you may have available.
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269perl v5.28.1                      2009-03-05                  File::ExtAttr(3)