SETXATTR(2) Linux Programmer's Manual SETXATTR(2)
setxattr, lsetxattr, fsetxattr - set an extended attribute value
#include <sys/types.h> #include <sys/xattr.h>
int setxattr(const char *path, const char *name, const void *value, size_t size, int flags); int lsetxattr(const char *path, const char *name, const void *value, size_t size, int flags); int fsetxattr(int fd, const char *name, const void *value, size_t size, int flags);
Extended attributes are name: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 stat(2) data). A complete overview of extended attributes concepts can be found in xattr(7).
setxattr() sets the value of the extended attribute identified by name and associated with the given path in the filesystem. The size argu- ment specifies the size (in bytes) of value; a zero-length value is permitted.
lsetxattr() is identical to setxattr(), except in the case of a sym- bolic link, where the extended attribute is set on the link itself, not the file that it refers to.
fsetxattr() is identical to setxattr(), only the extended attribute is set on the open file referred to by fd (as returned by open(2)) in place of path.
An extended attribute name is a null-terminated string. The name includes a namespace prefix; there may be several, disjoint namespaces associated with an individual inode. The value of an extended attribute is a chunk of arbitrary textual or binary data of specified length.
By default (i.e., flags is zero), the extended attribute will be cre- ated if it does not exist, or the value will be replaced if the attribute already exists. To modify these semantics, one of the fol- lowing values can be specified in flags:
XATTR_CREATE Perform a pure create, which fails if the named attribute exists already.
XATTR_REPLACE Perform a pure replace operation, which fails if the named attribute does not already exist.
On success, zero is returned. On failure, -1 is returned and errno is set appropriately.
EDQUOT Disk quota limits meant that there is insufficient space remain- ing to store the extended attribute.
EEXIST XATTR_CREATE was specified, and the attribute exists already.
ENOATTR XATTR_REPLACE was specified, and the attribute does not exist. (ENOATTR is defined to be a synonym for ENODATA in <attr/xattr.h>.)
ENOSPC There is insufficient space remaining to store the extended attribute.
ENOTSUP The namespace prefix of name is not valid.
ENOTSUP Extended attributes are not supported by the filesystem, or are disabled,
EPERM The file is marked immutable or append-only. (See ioctl_iflags(2).)
In addition, the errors documented in stat(2) can also occur.
These system calls have been available on Linux since kernel 2.4; glibc support is provided since version 2.3.
These system calls are Linux-specific.
getfattr(1), setfattr(1), getxattr(2), listxattr(2), open(2), removex- attr(2), stat(2), symlink(7), xattr(7)
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Linux 2017-03-13 SETXATTR(2)