man2/setxattr.2

.\" Copyright (C) Andreas Gruenbacher, February 2001
.\" Copyright (C) Silicon Graphics Inc, September 2001
.\"
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.\"
.TH SETXATTR 2 2021-03-22 "Linux" "Linux Programmer's Manual"
.SH NAME
setxattr, lsetxattr, fsetxattr \- set an extended attribute value
.SH SYNOPSIS
.fam C
.nf
.B #include <sys/xattr.h>
.PP
.BI "int setxattr(const char\ *" path ", const char\ *" name ,
.BI "              const void\ *" value ", size_t " size ", int " flags );
.BI "int lsetxattr(const char\ *" path ", const char\ *" name ,
.BI "              const void\ *" value ", size_t " size ", int " flags );
.BI "int fsetxattr(int " fd ", const char\ *" name ,
.BI "              const void\ *" value ", size_t " size ", int " flags );
.fi
.fam T
.SH DESCRIPTION
Extended attributes are
.IR name :\c
.I value
pairs associated with inodes (files, directories, symbolic links, etc.).
They are extensions to the normal attributes which are associated
with all inodes in the system (i.e., the
.BR stat (2)
data).
A complete overview of extended attributes concepts can be found in
.BR xattr (7).
.PP
.BR setxattr ()
sets the
.I value
of the extended attribute identified by
.I name
and associated with the given
.I path
in the filesystem.
The
.I size
argument specifies the size (in bytes) of
.IR value ;
a zero-length value is permitted.
.PP
.BR lsetxattr ()
is identical to
.BR setxattr (),
except in the case of a symbolic link, where the extended attribute is
set on the link itself, not the file that it refers to.
.PP
.BR fsetxattr ()
is identical to
.BR setxattr (),
only the extended attribute is set on the open file referred to by
.I fd
(as returned by
.BR open (2))
in place of
.IR path .
.PP
An extended attribute name is a null-terminated string.
The
.I name
includes a namespace prefix; there may be several, disjoint
namespaces associated with an individual inode.
The
.I value
of an extended attribute is a chunk of arbitrary textual or
binary data of specified length.
.PP
By default
(i.e.,
.IR flags
is zero),
the extended attribute will be created if it does not exist,
or the value will be replaced if the attribute already exists.
To modify these semantics, one of the following values can be specified in
.IR flags :
.TP
.B XATTR_CREATE
Perform a pure create, which fails if the named attribute exists already.
.TP
.B XATTR_REPLACE
Perform a pure replace operation,
which fails if the named attribute does not already exist.
.SH RETURN VALUE
On success, zero is returned.
On failure, \-1 is returned and
.I errno
is set to indicate the error.
.SH ERRORS
.TP
.B EDQUOT
Disk quota limits meant that
there is insufficient space remaining to store the extended attribute.
.TP
.B EEXIST
.B XATTR_CREATE
was specified, and the attribute exists already.
.TP
.B ENODATA
.B XATTR_REPLACE
was specified, and the attribute does not exist.
.\" .RB ( ENOATTR
.\" is defined to be a synonym for
.\" .BR ENODATA
.\" in
.\" .IR <attr/attributes.h> .)
.TP
.B ENOSPC
There is insufficient space remaining to store the extended attribute.
.TP
.B ENOTSUP
The namespace prefix of
.I name
is not valid.
.TP
.B ENOTSUP
Extended attributes are not supported by the filesystem, or are disabled,
.TP
.B EPERM
The file is marked immutable or append-only.
(See
.BR ioctl_iflags (2).)
.PP
In addition, the errors documented in
.BR stat (2)
can also occur.
.TP
.B ERANGE
The size of
.I name
or
.I value
exceeds a filesystem-specific limit.
.SH VERSIONS
These system calls have been available on Linux since kernel 2.4;
glibc support is provided since version 2.3.
.SH CONFORMING TO
These system calls are Linux-specific.
.\" .SH AUTHORS
.\" Andreas Gruenbacher,
.\" .RI < a.gruenbacher@computer.org >
.\" and the SGI XFS development team,
.\" .RI < linux-xfs@oss.sgi.com >.
.\" Please send any bug reports or comments to these addresses.
.SH SEE ALSO
.BR getfattr (1),
.BR setfattr (1),
.BR getxattr (2),
.BR listxattr (2),
.BR open (2),
.BR removexattr (2),
.BR stat (2),
.BR symlink (7),
.BR xattr (7)