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 September 23, 2020 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_BENEATH 98Only allow to change flags for a file which is beneath of 99the topping directory. 100See the description of the 101.Dv O_BENEATH 102flag in the 103.Xr open 2 104manual page. 105.It Dv AT_RESOLVE_BENEATH 106Only walks paths below the topping directory. 107See the description of the 108.Dv O_RESOLVE_BENEATH 109flag in the 110.Xr open 2 111manual page. 112.El 113.Pp 114If 115.Fn chflagsat 116is passed the special value 117.Dv AT_FDCWD 118in the 119.Fa fd 120parameter, the current working directory is used. 121If also 122.Fa atflag 123is zero, the behavior is identical to a call to 124.Fn chflags . 125.Pp 126The flags specified are formed by 127.Em or Ns 'ing 128the following values 129.Pp 130.Bl -tag -width ".Dv SF_IMMUTABLE" -compact -offset indent 131.It Dv SF_APPEND 132The file may only be appended to. 133.It Dv SF_ARCHIVED 134The file has been archived. 135This flag means the opposite of the DOS, Windows and CIFS 136FILE_ATTRIBUTE_ARCHIVE attribute. 137This flag has been deprecated, and may be removed in a future release. 138.It Dv SF_IMMUTABLE 139The file may not be changed. 140.It Dv SF_NOUNLINK 141The file may not be renamed or deleted. 142.It Dv SF_SNAPSHOT 143The file is a snapshot file. 144.It Dv UF_APPEND 145The file may only be appended to. 146.It Dv UF_ARCHIVE 147The file needs to be archived. 148This flag has the same meaning as the DOS, Windows and CIFS 149FILE_ATTRIBUTE_ARCHIVE attribute. 150Filesystems in FreeBSD may or may not have special handling for this flag. 151For instance, ZFS tracks changes to files and will set this bit when a 152file is updated. 153UFS only stores the flag, and relies on the application to change it when 154needed. 155.It Dv UF_HIDDEN 156The file may be hidden from directory listings at the application's 157discretion. 158The file has the DOS, Windows and CIFS FILE_ATTRIBUTE_HIDDEN attribute. 159.It Dv UF_IMMUTABLE 160The file may not be changed. 161.It Dv UF_NODUMP 162Do not dump the file. 163.It Dv UF_NOUNLINK 164The file may not be renamed or deleted. 165.It Dv UF_OFFLINE 166The file is offline, or has the Windows and CIFS FILE_ATTRIBUTE_OFFLINE 167attribute. 168Filesystems in FreeBSD store and display this flag, but do not provide any 169special handling when it is set. 170.It Dv UF_OPAQUE 171The directory is opaque when viewed through a union stack. 172.It Dv UF_READONLY 173The file is read only, and may not be written or appended. 174Filesystems may use this flag to maintain compatibility with the DOS, Windows 175and CIFS FILE_ATTRIBUTE_READONLY attribute. 176.It Dv UF_REPARSE 177The file contains a Windows reparse point and has the Windows and CIFS 178FILE_ATTRIBUTE_REPARSE_POINT attribute. 179.It Dv UF_SPARSE 180The file has the Windows FILE_ATTRIBUTE_SPARSE_FILE attribute. 181This may also be used by a filesystem to indicate a sparse file. 182.It Dv UF_SYSTEM 183The file has the DOS, Windows and CIFS FILE_ATTRIBUTE_SYSTEM attribute. 184Filesystems in FreeBSD may store and display this flag, but do not provide 185any special handling when it is set. 186.El 187.Pp 188If one of 189.Dv SF_IMMUTABLE , SF_APPEND , 190or 191.Dv SF_NOUNLINK 192is set a non-super-user cannot change any flags and even the super-user 193can change flags only if securelevel is 0. 194(See 195.Xr init 8 196for details.) 197.Pp 198The 199.Dv UF_IMMUTABLE , UF_APPEND , UF_NOUNLINK , UF_NODUMP , 200and 201.Dv UF_OPAQUE 202flags may be set or unset by either the owner of a file or the super-user. 203.Pp 204The 205.Dv SF_IMMUTABLE , SF_APPEND , SF_NOUNLINK , 206and 207.Dv SF_ARCHIVED 208flags may only be set or unset by the super-user. 209Attempts to toggle these flags by non-super-users are rejected. 210These flags may be set at any time, but normally may only be unset when 211the system is in single-user mode. 212(See 213.Xr init 8 214for details.) 215.Pp 216The implementation of all flags is filesystem-dependent. 217See the description of the 218.Dv UF_ARCHIVE 219flag above for one example of the differences in behavior. 220Care should be exercised when writing applications to account for 221support or lack of support of these flags in various filesystems. 222.Pp 223The 224.Dv SF_SNAPSHOT 225flag is maintained by the system and cannot be toggled. 226.Sh RETURN VALUES 227.Rv -std 228.Sh ERRORS 229The 230.Fn chflags 231system call will fail if: 232.Bl -tag -width Er 233.It Bq Er ENOTDIR 234A component of the path prefix is not a directory. 235.It Bq Er ENAMETOOLONG 236A component of a pathname exceeded 255 characters, 237or an entire path name exceeded 1023 characters. 238.It Bq Er ENOENT 239The named file does not exist. 240.It Bq Er EACCES 241Search permission is denied for a component of the path prefix. 242.It Bq Er ELOOP 243Too many symbolic links were encountered in translating the pathname. 244.It Bq Er EPERM 245The effective user ID does not match the owner of the file and 246the effective user ID is not the super-user. 247.It Bq Er EPERM 248One of 249.Dv SF_IMMUTABLE , SF_APPEND , 250or 251.Dv SF_NOUNLINK 252is set and the user is either not the super-user or 253securelevel is greater than 0. 254.It Bq Er EPERM 255A non-super-user attempted to toggle one of 256.Dv SF_ARCHIVED , SF_IMMUTABLE , SF_APPEND , 257or 258.Dv SF_NOUNLINK . 259.It Bq Er EPERM 260An attempt was made to toggle the 261.Dv SF_SNAPSHOT 262flag. 263.It Bq Er EROFS 264The named file resides on a read-only file system. 265.It Bq Er EFAULT 266The 267.Fa path 268argument 269points outside the process's allocated address space. 270.It Bq Er EIO 271An 272.Tn I/O 273error occurred while reading from or writing to the file system. 274.It Bq Er EINTEGRITY 275Corrupted data was detected while reading from the file system. 276.It Bq Er EOPNOTSUPP 277The underlying file system does not support file flags, or 278does not support all of the flags set in 279.Fa flags . 280.El 281.Pp 282The 283.Fn fchflags 284system call will fail if: 285.Bl -tag -width Er 286.It Bq Er EBADF 287The descriptor is not valid. 288.It Bq Er EINVAL 289The 290.Fa fd 291argument 292refers to a socket, not to a file. 293.It Bq Er EPERM 294The effective user ID does not match the owner of the file and 295the effective user ID is not the super-user. 296.It Bq Er EPERM 297One of 298.Dv SF_IMMUTABLE , SF_APPEND , 299or 300.Dv SF_NOUNLINK 301is set and the user is either not the super-user or 302securelevel is greater than 0. 303.It Bq Er EPERM 304A non-super-user attempted to toggle one of 305.Dv SF_ARCHIVED , SF_IMMUTABLE , SF_APPEND , 306or 307.Dv SF_NOUNLINK . 308.It Bq Er EPERM 309An attempt was made to toggle the 310.Dv SF_SNAPSHOT 311flag. 312.It Bq Er EROFS 313The file resides on a read-only file system. 314.It Bq Er EIO 315An 316.Tn I/O 317error occurred while reading from or writing to the file system. 318.It Bq Er EINTEGRITY 319Corrupted data was detected while reading from the file system. 320.It Bq Er EOPNOTSUPP 321The underlying file system does not support file flags, or 322does not support all of the flags set in 323.Fa flags . 324.It Bq Er ENOTCAPABLE 325.Fa path 326is an absolute path, 327or contained a ".." component leading to a 328directory outside of the directory hierarchy specified by 329.Fa fd , 330and the process is in capability mode. 331.It Bq Er ENOTCAPABLE 332The 333.Dv AT_BENEATH 334flag was provided to 335.Fn chflagsat , 336and the absolute 337.Fa path 338does not have its tail fully contained under the topping directory, 339or the relative 340.Fa path 341escapes it. 342.El 343.Sh SEE ALSO 344.Xr chflags 1 , 345.Xr fflagstostr 3 , 346.Xr strtofflags 3 , 347.Xr init 8 , 348.Xr mount_unionfs 8 349.Sh HISTORY 350The 351.Fn chflags 352and 353.Fn fchflags 354system calls first appeared in 355.Bx 4.4 . 356The 357.Fn lchflags 358system call first appeared in 359.Fx 5.0 . 360The 361.Fn chflagsat 362system call first appeared in 363.Fx 10.0 . 364