CHFLAGS(2)

NAME
chflags, lchflags, fchflags - set file flags

LIBRARY
libc

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

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 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_NOUNLINK
    The file may not be renamed or deleted.
UF_OPAQUE
    The directory is opaque when viewed through a union stack.
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_SNAPSHOT
    The file is a snapshot file.

If one of SF_IMMUTABLE, SF_APPEND, or SF_NOUNLINK is set a non-super-user cannot change any flags and even the super-user can change flags only if securelevel is greater than 0. (See init(8) for details.)

The UF_IMMUTABLE, UF_APPEND, UF_NOUNLINK, UF_NODUMP, and UF_OPAQUE flags may be set or unset by either the owner of a file or the super-user.

The SF_IMMUTABLE, SF_APPEND, SF_NOUNLINK, and SF_ARCHIVED flags may only be set or unset by the super-user. Attempts to set these flags by non-super-users are rejected, attempts by non-superusers to clear flags that are already unset 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.)

The SF_SNAPSHOT flag is maintained by the system and cannot be changed by any user.

RETURN VALUES

ERRORS
The chflags() system call 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.

[EPERM]
    One of SF_IMMUTABLE, SF_APPEND, or SF_NOUNLINK is set and the user is either not the super-user or securelevel is greater than 0.

[EPERM]
    A non-super-user tries to set one of SF_ARCHIVED, SF_IMMUTABLE, SF_APPEND, or SF_NOUNLINK.

[EPERM]
    User tries to set or remove the SF_SNAPSHOT flag.

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

[EFAULT]
    The path argument 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.

The fchflags() system call will fail if:

[EBADF]
    The descriptor is not valid.

[EINVAL]
    The fd argument 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.

[EPERM]
    One of SF_IMMUTABLE, SF_APPEND, or SF_NOUNLINK is set and the user is either not the super-user or securelevel is greater than 0.

[EPERM]
    A non-super-user tries to set one of SF_ARCHIVED, SF_IMMUTABLE, SF_APPEND, or SF_NOUNLINK.

[EPERM]
    User tries to set or remove the SF_SNAPSHOT flag.

[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), mount_unionfs(8)

HISTORY
The chflags() and fchflags() system calls first appeared in 4.4BSD.