SETXATTR(2) System Calls Manual SETXATTR(2)

setxattr, lsetxattr, fsetxattr - set an extended attribute value

Standard C library (libc, -lc)

#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 argument specifies the size (in bytes) of value; a zero-length value is permitted.

lsetxattr() is identical to 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.

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 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 flags:

Perform a pure create, which fails if the named attribute exists already.
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 to indicate the error.

Disk quota limits meant that there is insufficient space remaining to store the extended attribute.
XATTR_CREATE was specified, and the attribute exists already.
XATTR_REPLACE was specified, and the attribute does not exist.
There is insufficient space remaining to store the extended attribute.
The namespace prefix of name is not valid.
Extended attributes are not supported by the filesystem, or are disabled,
The file is marked immutable or append-only. (See ioctl_iflags(2).)

In addition, the errors documented in stat(2) can also occur.

The size of name or value exceeds a filesystem-specific limit.

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), removexattr(2), stat(2), symlink(7), xattr(7)

2022-10-09 Linux man-pages 6.01