CHFLAGS(2)

NAME
chflags, lchflags, fchflags, chflagsat - set file flags

LIBRARY
libc

SYNOPSIS
#include <sys/stat.h>
#include <unistd.h>
int
chflags(const char *path, unsigned long flags);
int
lchflags(const char *path, unsigned long flags);
int
fchflags(int fd, unsigned long flags);
int
chflagsat(int fd, const char *path, unsigned long flags, int atflag);

DESCRIPTION
The file whose name is given by path or referenced by the descriptor fd has its flags changed to flags.

The lchflags() system call is like chflags() except in the case where the named file is a symbolic link, in which case lchflags() will change the flags of the link itself, rather than the file it points to.

The chflagsat() is equivalent to either chflags() or lchflags() depending on the atflag except in the case where path specifies a relative path. In this case the file to be changed is determined relative to the directory associated with the file descriptor fd instead of the current working directory. The values for the atflag are constructed by a bitwise-inclusive OR of flags from the following list, defined in <fcntl.h>:

AT_SYMLINK_NOFOLLOW
    If path names a symbolic link, then the flags of the symbolic link are changed.

If chflagsat() is passed the special value AT_FDCWD in the fd parameter, the current working directory is used. If also atflag is zero, the behavior is identical to a call to chflags().

The flags specified are formed by or'ing the following values

UF_NODUMP
    Do not dump the file.
UF_IMMUTABLE
    The file may not be changed.
UF_APPEND
    The file may only be appended to.
UF_OPAQUE
    The directory is opaque when viewed through a union stack.
UF_NOUNLINK
    The file may not be renamed or deleted.
UF_NOHISTORY
    Do not retain history for file.
UF_CACHE
    Enable swapcache(8) data caching. The flag is recursive and need only be set on a top-level directory.
SF_ARCHIVED
    The file may be archived.
SF_IMMUTABLE
    The file may not be changed.
SF_APPEND
    The file may only be appended to.
SF_NOUNLINK
    The file may not be renamed or deleted.
SF_NOHISTORY
    Do not retain history for file.
SF_NOCACHE
    Disable swapcache(8) data caching. The flag is recursive and need only be set on a top-level directory.

The “UF_” prefixed flags may be set or unset by either the owner of a file or the super-user.

The “SF_” prefixed flags may only be set or unset by the super-user. Attempts by the non-super-user to set the super-user only flags are silently ignored. These flags may be set at any time, but normally may only be unset when the system is in single-user mode. (See init(8) for details.)

RETURN VALUES

ERRORS
Chflags() will fail if:

[ENOTDIR]
    A component of the path prefix is not a directory.

[ENAMETOOLONG]
    A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.

[ENOENT]
    The named file does not exist.

[EACCES]
    Search permission is denied for a component of the path prefix.

[ELOOP]
    Too many symbolic links were encountered in translating the pathname.

[EPERM]
    The effective user ID does not match the owner of the file and the effective user ID is not the super-user.

[EROFS]
    The named file resides on a read-only file system.

[EFAULT]
    Path points outside the process's allocated address space.

[EIO]
    An I/O error occurred while reading from or writing to the file system.

[EOPNOTSUPP]
    The underlying file system does not support file flags.

Fchflags() will fail if:

[EBADF]
    The descriptor is not valid.

[EINVAL]
    fd refers to a socket, not to a file.

[EPERM]
    The effective user ID does not match the owner of the file and the effective user ID is not the super-user.

[EROFS]
    The file resides on a read-only file system.

[EIO]
    An I/O error occurred while reading from or writing to the file system.

[EOPNOTSUPP]
    The underlying file system does not support file flags.

SEE ALSO
chflags(1), fflagstostr(3), strtofflags(3), init(8), swapcache(8)

HISTORY
The chflags and fchflags functions first appeared in 4.4BSD.