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 March 30, 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.It Dv AT_EMPTY_PATH 107If the 108.Fa path 109argument is an empty string, operate on the file or directory 110referenced by the descriptor 111.Fa fd . 112If 113.Fa fd 114is equal to 115.Dv AT_FDCWD , 116operate on the current working directory. 117.El 118.Pp 119If 120.Fn chflagsat 121is passed the special value 122.Dv AT_FDCWD 123in the 124.Fa fd 125parameter, the current working directory is used. 126If also 127.Fa atflag 128is zero, the behavior is identical to a call to 129.Fn chflags . 130.Pp 131The flags specified are formed by 132.Em or Ns 'ing 133the following values 134.Pp 135.Bl -tag -width ".Dv SF_IMMUTABLE" -compact -offset indent 136.It Dv SF_APPEND 137The file may only be appended to. 138.It Dv SF_ARCHIVED 139The file has been archived. 140This flag means the opposite of the DOS, Windows and CIFS 141FILE_ATTRIBUTE_ARCHIVE attribute. 142This flag has been deprecated, and may be removed in a future release. 143.It Dv SF_IMMUTABLE 144The file may not be changed. 145.It Dv SF_NOUNLINK 146The file may not be renamed or deleted. 147.It Dv SF_SNAPSHOT 148The file is a snapshot file. 149.It Dv UF_APPEND 150The file may only be appended to. 151.It Dv UF_ARCHIVE 152The file needs to be archived. 153This flag has the same meaning as the DOS, Windows and CIFS 154FILE_ATTRIBUTE_ARCHIVE attribute. 155Filesystems in FreeBSD may or may not have special handling for this flag. 156For instance, ZFS tracks changes to files and will set this bit when a 157file is updated. 158UFS only stores the flag, and relies on the application to change it when 159needed. 160.It Dv UF_HIDDEN 161The file may be hidden from directory listings at the application's 162discretion. 163The file has the DOS, Windows and CIFS FILE_ATTRIBUTE_HIDDEN attribute. 164.It Dv UF_IMMUTABLE 165The file may not be changed. 166.It Dv UF_NODUMP 167Do not dump the file. 168.It Dv UF_NOUNLINK 169The file may not be renamed or deleted. 170.It Dv UF_OFFLINE 171The file is offline, or has the Windows and CIFS FILE_ATTRIBUTE_OFFLINE 172attribute. 173Filesystems in FreeBSD store and display this flag, but do not provide any 174special handling when it is set. 175.It Dv UF_OPAQUE 176The directory is opaque when viewed through a union stack. 177.It Dv UF_READONLY 178The file is read only, and may not be written or appended. 179Filesystems may use this flag to maintain compatibility with the DOS, Windows 180and CIFS FILE_ATTRIBUTE_READONLY attribute. 181.It Dv UF_REPARSE 182The file contains a Windows reparse point and has the Windows and CIFS 183FILE_ATTRIBUTE_REPARSE_POINT attribute. 184.It Dv UF_SPARSE 185The file has the Windows FILE_ATTRIBUTE_SPARSE_FILE attribute. 186This may also be used by a filesystem to indicate a sparse file. 187.It Dv UF_SYSTEM 188The file has the DOS, Windows and CIFS FILE_ATTRIBUTE_SYSTEM attribute. 189Filesystems in FreeBSD may store and display this flag, but do not provide 190any special handling when it is set. 191.El 192.Pp 193If one of 194.Dv SF_IMMUTABLE , SF_APPEND , 195or 196.Dv SF_NOUNLINK 197is set a non-super-user cannot change any flags and even the super-user 198can change flags only if securelevel is 0. 199(See 200.Xr init 8 201for details.) 202.Pp 203The 204.Dv UF_IMMUTABLE , UF_APPEND , UF_NOUNLINK , UF_NODUMP , 205and 206.Dv UF_OPAQUE 207flags may be set or unset by either the owner of a file or the super-user. 208.Pp 209The 210.Dv SF_IMMUTABLE , SF_APPEND , SF_NOUNLINK , 211and 212.Dv SF_ARCHIVED 213flags may only be set or unset by the super-user. 214Attempts to toggle these flags by non-super-users are rejected. 215These flags may be set at any time, but normally may only be unset when 216the system is in single-user mode. 217(See 218.Xr init 8 219for details.) 220.Pp 221The implementation of all flags is filesystem-dependent. 222See the description of the 223.Dv UF_ARCHIVE 224flag above for one example of the differences in behavior. 225Care should be exercised when writing applications to account for 226support or lack of support of these flags in various filesystems. 227.Pp 228The 229.Dv SF_SNAPSHOT 230flag is maintained by the system and cannot be toggled. 231.Sh RETURN VALUES 232.Rv -std 233.Sh ERRORS 234The 235.Fn chflags 236system call will fail if: 237.Bl -tag -width Er 238.It Bq Er ENOTDIR 239A component of the path prefix is not a directory. 240.It Bq Er ENAMETOOLONG 241A component of a pathname exceeded 255 characters, 242or an entire path name exceeded 1023 characters. 243.It Bq Er ENOENT 244The named file does not exist. 245.It Bq Er EACCES 246Search permission is denied for a component of the path prefix. 247.It Bq Er ELOOP 248Too many symbolic links were encountered in translating the pathname. 249.It Bq Er EPERM 250The effective user ID does not match the owner of the file and 251the effective user ID is not the super-user. 252.It Bq Er EPERM 253One of 254.Dv SF_IMMUTABLE , SF_APPEND , 255or 256.Dv SF_NOUNLINK 257is set and the user is either not the super-user or 258securelevel is greater than 0. 259.It Bq Er EPERM 260A non-super-user attempted to toggle one of 261.Dv SF_ARCHIVED , SF_IMMUTABLE , SF_APPEND , 262or 263.Dv SF_NOUNLINK . 264.It Bq Er EPERM 265An attempt was made to toggle the 266.Dv SF_SNAPSHOT 267flag. 268.It Bq Er EROFS 269The named file resides on a read-only file system. 270.It Bq Er EFAULT 271The 272.Fa path 273argument 274points outside the process's allocated address space. 275.It Bq Er EIO 276An 277.Tn I/O 278error occurred while reading from or writing to the file system. 279.It Bq Er EINTEGRITY 280Corrupted data was detected while reading from the file system. 281.It Bq Er EOPNOTSUPP 282The underlying file system does not support file flags, or 283does not support all of the flags set in 284.Fa flags . 285.El 286.Pp 287The 288.Fn fchflags 289system call will fail if: 290.Bl -tag -width Er 291.It Bq Er EBADF 292The descriptor is not valid. 293.It Bq Er EINVAL 294The 295.Fa fd 296argument 297refers to a socket, not to a file. 298.It Bq Er EPERM 299The effective user ID does not match the owner of the file and 300the effective user ID is not the super-user. 301.It Bq Er EPERM 302One of 303.Dv SF_IMMUTABLE , SF_APPEND , 304or 305.Dv SF_NOUNLINK 306is set and the user is either not the super-user or 307securelevel is greater than 0. 308.It Bq Er EPERM 309A non-super-user attempted to toggle one of 310.Dv SF_ARCHIVED , SF_IMMUTABLE , SF_APPEND , 311or 312.Dv SF_NOUNLINK . 313.It Bq Er EPERM 314An attempt was made to toggle the 315.Dv SF_SNAPSHOT 316flag. 317.It Bq Er EROFS 318The file resides on a read-only file system. 319.It Bq Er EIO 320An 321.Tn I/O 322error occurred while reading from or writing to the file system. 323.It Bq Er EINTEGRITY 324Corrupted data was detected while reading from the file system. 325.It Bq Er EOPNOTSUPP 326The underlying file system does not support file flags, or 327does not support all of the flags set in 328.Fa flags . 329.It Bq Er ENOTCAPABLE 330.Fa path 331is an absolute path, 332or contained a ".." component leading to a 333directory outside of the directory hierarchy specified by 334.Fa fd , 335and the process is in capability mode or the 336.Dv AT_RESOLVE_BENEATH 337flag was specified. 338.El 339.Sh SEE ALSO 340.Xr chflags 1 , 341.Xr fflagstostr 3 , 342.Xr strtofflags 3 , 343.Xr init 8 , 344.Xr mount_unionfs 8 345.Sh HISTORY 346The 347.Fn chflags 348and 349.Fn fchflags 350system calls first appeared in 351.Bx 4.4 . 352The 353.Fn lchflags 354system call first appeared in 355.Fx 5.0 . 356The 357.Fn chflagsat 358system call first appeared in 359.Fx 10.0 . 360