1.\" Copyright (c) 1989, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)chflags.2 8.3 (Berkeley) 5/2/95 29.\" $FreeBSD$ 30.\" 31.Dd February 23, 2021 32.Dt CHFLAGS 2 33.Os 34.Sh NAME 35.Nm chflags , 36.Nm lchflags , 37.Nm fchflags , 38.Nm chflagsat 39.Nd set file flags 40.Sh LIBRARY 41.Lb libc 42.Sh SYNOPSIS 43.In sys/stat.h 44.In unistd.h 45.Ft int 46.Fn chflags "const char *path" "unsigned long flags" 47.Ft int 48.Fn lchflags "const char *path" "unsigned long flags" 49.Ft int 50.Fn fchflags "int fd" "unsigned long flags" 51.Ft int 52.Fn chflagsat "int fd" "const char *path" "unsigned long flags" "int atflag" 53.Sh DESCRIPTION 54The file whose name 55is given by 56.Fa path 57or referenced by the descriptor 58.Fa fd 59has its flags changed to 60.Fa flags . 61.Pp 62The 63.Fn lchflags 64system call is like 65.Fn chflags 66except in the case where the named file is a symbolic link, 67in which case 68.Fn lchflags 69will change the flags of the link itself, 70rather than the file it points to. 71.Pp 72The 73.Fn chflagsat 74is equivalent to either 75.Fn chflags 76or 77.Fn lchflags 78depending on the 79.Fa atflag 80except in the case where 81.Fa path 82specifies a relative path. 83In this case the file to be changed is determined relative to the directory 84associated with the file descriptor 85.Fa fd 86instead of the current working directory. 87The values for the 88.Fa atflag 89are constructed by a bitwise-inclusive OR of flags from the following list, 90defined in 91.In fcntl.h : 92.Bl -tag -width indent 93.It Dv AT_SYMLINK_NOFOLLOW 94If 95.Fa path 96names a symbolic link, then the flags of the symbolic link are changed. 97.It Dv AT_RESOLVE_BENEATH 98Only walk paths below the directory specified by the 99.Ar fd 100descriptor. 101See the description of the 102.Dv O_RESOLVE_BENEATH 103flag in the 104.Xr open 2 105manual page. 106.El 107.Pp 108If 109.Fn chflagsat 110is passed the special value 111.Dv AT_FDCWD 112in the 113.Fa fd 114parameter, the current working directory is used. 115If also 116.Fa atflag 117is zero, the behavior is identical to a call to 118.Fn chflags . 119.Pp 120The flags specified are formed by 121.Em or Ns 'ing 122the following values 123.Pp 124.Bl -tag -width ".Dv SF_IMMUTABLE" -compact -offset indent 125.It Dv SF_APPEND 126The file may only be appended to. 127.It Dv SF_ARCHIVED 128The file has been archived. 129This flag means the opposite of the DOS, Windows and CIFS 130FILE_ATTRIBUTE_ARCHIVE attribute. 131This flag has been deprecated, and may be removed in a future release. 132.It Dv SF_IMMUTABLE 133The file may not be changed. 134.It Dv SF_NOUNLINK 135The file may not be renamed or deleted. 136.It Dv SF_SNAPSHOT 137The file is a snapshot file. 138.It Dv UF_APPEND 139The file may only be appended to. 140.It Dv UF_ARCHIVE 141The file needs to be archived. 142This flag has the same meaning as the DOS, Windows and CIFS 143FILE_ATTRIBUTE_ARCHIVE attribute. 144Filesystems in FreeBSD may or may not have special handling for this flag. 145For instance, ZFS tracks changes to files and will set this bit when a 146file is updated. 147UFS only stores the flag, and relies on the application to change it when 148needed. 149.It Dv UF_HIDDEN 150The file may be hidden from directory listings at the application's 151discretion. 152The file has the DOS, Windows and CIFS FILE_ATTRIBUTE_HIDDEN attribute. 153.It Dv UF_IMMUTABLE 154The file may not be changed. 155.It Dv UF_NODUMP 156Do not dump the file. 157.It Dv UF_NOUNLINK 158The file may not be renamed or deleted. 159.It Dv UF_OFFLINE 160The file is offline, or has the Windows and CIFS FILE_ATTRIBUTE_OFFLINE 161attribute. 162Filesystems in FreeBSD store and display this flag, but do not provide any 163special handling when it is set. 164.It Dv UF_OPAQUE 165The directory is opaque when viewed through a union stack. 166.It Dv UF_READONLY 167The file is read only, and may not be written or appended. 168Filesystems may use this flag to maintain compatibility with the DOS, Windows 169and CIFS FILE_ATTRIBUTE_READONLY attribute. 170.It Dv UF_REPARSE 171The file contains a Windows reparse point and has the Windows and CIFS 172FILE_ATTRIBUTE_REPARSE_POINT attribute. 173.It Dv UF_SPARSE 174The file has the Windows FILE_ATTRIBUTE_SPARSE_FILE attribute. 175This may also be used by a filesystem to indicate a sparse file. 176.It Dv UF_SYSTEM 177The file has the DOS, Windows and CIFS FILE_ATTRIBUTE_SYSTEM attribute. 178Filesystems in FreeBSD may store and display this flag, but do not provide 179any special handling when it is set. 180.El 181.Pp 182If one of 183.Dv SF_IMMUTABLE , SF_APPEND , 184or 185.Dv SF_NOUNLINK 186is set a non-super-user cannot change any flags and even the super-user 187can change flags only if securelevel is 0. 188(See 189.Xr init 8 190for details.) 191.Pp 192The 193.Dv UF_IMMUTABLE , UF_APPEND , UF_NOUNLINK , UF_NODUMP , 194and 195.Dv UF_OPAQUE 196flags may be set or unset by either the owner of a file or the super-user. 197.Pp 198The 199.Dv SF_IMMUTABLE , SF_APPEND , SF_NOUNLINK , 200and 201.Dv SF_ARCHIVED 202flags may only be set or unset by the super-user. 203Attempts to toggle these flags by non-super-users are rejected. 204These flags may be set at any time, but normally may only be unset when 205the system is in single-user mode. 206(See 207.Xr init 8 208for details.) 209.Pp 210The implementation of all flags is filesystem-dependent. 211See the description of the 212.Dv UF_ARCHIVE 213flag above for one example of the differences in behavior. 214Care should be exercised when writing applications to account for 215support or lack of support of these flags in various filesystems. 216.Pp 217The 218.Dv SF_SNAPSHOT 219flag is maintained by the system and cannot be toggled. 220.Sh RETURN VALUES 221.Rv -std 222.Sh ERRORS 223The 224.Fn chflags 225system call will fail if: 226.Bl -tag -width Er 227.It Bq Er ENOTDIR 228A component of the path prefix is not a directory. 229.It Bq Er ENAMETOOLONG 230A component of a pathname exceeded 255 characters, 231or an entire path name exceeded 1023 characters. 232.It Bq Er ENOENT 233The named file does not exist. 234.It Bq Er EACCES 235Search permission is denied for a component of the path prefix. 236.It Bq Er ELOOP 237Too many symbolic links were encountered in translating the pathname. 238.It Bq Er EPERM 239The effective user ID does not match the owner of the file and 240the effective user ID is not the super-user. 241.It Bq Er EPERM 242One of 243.Dv SF_IMMUTABLE , SF_APPEND , 244or 245.Dv SF_NOUNLINK 246is set and the user is either not the super-user or 247securelevel is greater than 0. 248.It Bq Er EPERM 249A non-super-user attempted to toggle one of 250.Dv SF_ARCHIVED , SF_IMMUTABLE , SF_APPEND , 251or 252.Dv SF_NOUNLINK . 253.It Bq Er EPERM 254An attempt was made to toggle the 255.Dv SF_SNAPSHOT 256flag. 257.It Bq Er EROFS 258The named file resides on a read-only file system. 259.It Bq Er EFAULT 260The 261.Fa path 262argument 263points outside the process's allocated address space. 264.It Bq Er EIO 265An 266.Tn I/O 267error occurred while reading from or writing to the file system. 268.It Bq Er EINTEGRITY 269Corrupted data was detected while reading from the file system. 270.It Bq Er EOPNOTSUPP 271The underlying file system does not support file flags, or 272does not support all of the flags set in 273.Fa flags . 274.El 275.Pp 276The 277.Fn fchflags 278system call will fail if: 279.Bl -tag -width Er 280.It Bq Er EBADF 281The descriptor is not valid. 282.It Bq Er EINVAL 283The 284.Fa fd 285argument 286refers to a socket, not to a file. 287.It Bq Er EPERM 288The effective user ID does not match the owner of the file and 289the effective user ID is not the super-user. 290.It Bq Er EPERM 291One of 292.Dv SF_IMMUTABLE , SF_APPEND , 293or 294.Dv SF_NOUNLINK 295is set and the user is either not the super-user or 296securelevel is greater than 0. 297.It Bq Er EPERM 298A non-super-user attempted to toggle one of 299.Dv SF_ARCHIVED , SF_IMMUTABLE , SF_APPEND , 300or 301.Dv SF_NOUNLINK . 302.It Bq Er EPERM 303An attempt was made to toggle the 304.Dv SF_SNAPSHOT 305flag. 306.It Bq Er EROFS 307The file resides on a read-only file system. 308.It Bq Er EIO 309An 310.Tn I/O 311error occurred while reading from or writing to the file system. 312.It Bq Er EINTEGRITY 313Corrupted data was detected while reading from the file system. 314.It Bq Er EOPNOTSUPP 315The underlying file system does not support file flags, or 316does not support all of the flags set in 317.Fa flags . 318.It Bq Er ENOTCAPABLE 319.Fa path 320is an absolute path, 321or contained a ".." component leading to a 322directory outside of the directory hierarchy specified by 323.Fa fd , 324and the process is in capability mode or the 325.Dv AT_RESOLVE_BENEATH 326flag was specified. 327.El 328.Sh SEE ALSO 329.Xr chflags 1 , 330.Xr fflagstostr 3 , 331.Xr strtofflags 3 , 332.Xr init 8 , 333.Xr mount_unionfs 8 334.Sh HISTORY 335The 336.Fn chflags 337and 338.Fn fchflags 339system calls first appeared in 340.Bx 4.4 . 341The 342.Fn lchflags 343system call first appeared in 344.Fx 5.0 . 345The 346.Fn chflagsat 347system call first appeared in 348.Fx 10.0 . 349