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CHFLAGS(1) General Commands Manual CHFLAGS(1)

chflags — change file flags

chflags [-fhv] [-R [-H | -L | -P]] flags file ...

The chflags utility modifies the file flags of the listed files as specified by the flags operand.

The options are as follows:

Do not display a diagnostic message if chflags could not modify the flags for file, nor modify the exit status to reflect such failures.
If the -R option is specified, symbolic links on the command line are followed and hence unaffected by the command. (Symbolic links encountered during traversal are not followed.)
If the file is a symbolic link, change the file flags of the link itself rather than the file to which it points.
If the -R option is specified, all symbolic links are followed.
If the -R option is specified, no symbolic links are followed. This is the default.
Change the file flags of the file hierarchies rooted in the files, instead of just the files themselves. Beware of unintentionally matching the “..” hard link to the parent directory when using wildcards like “.*”.
Cause chflags to be verbose, showing filenames as the flags are modified. If the -v option is specified more than once, the old and new flags of the file will also be printed, in octal notation.

The flags are specified as an octal number or a comma separated list of keywords. The following keywords are currently defined:

, archived
set the archived flag (super-user only)
set the opaque flag (owner or super-user only)
set the nodump flag (owner or super-user only)
set the system nohistory flag (super-user only)
, nohistory
set the user nohistory flag (owner or super-user only)
, sappend
set the system append-only flag (super-user only)
, schange, simmutable
set the system immutable flag (super-user only)
, sunlink
set the system undeletable flag (super-user only)
, uappend
set the user append-only flag (owner or super-user only)
, uchange, uimmutable
set the user immutable flag (owner or super-user only)
, uunlink
set the user undeletable flag (owner or super-user only)
, ucache
control the data swapcache(8) (recursive, does not cross mounts) (owner or super-user only)
control the data swapcache(8) (recursive, does not cross mounts) (super-user only)

If a “no” prefix is added or removed from a keyword, the meaning is negated. For example:

clear the user immutable flag (owner or super-user only)
clear the nodump flag (owner or super-user only)

A few of the octal values include:

Clear all file flags.
Translates to the nodump keyword.
Translates to the uchg keyword.
Translates to the uchg, nodump keywords.
Translates to the uappnd keyword.
Translates to the opaque keyword.
translates to the uunlnk keyword.

Other combinations of keywords may be placed by using the octets assigned; however, these are the most notable.

Unless the -H, -L, or -h options are given, chflags on a symbolic link always succeeds and has no effect. The -H, -L and -P options are ignored unless the -R option is specified. In addition, these options override each other and the command's actions are determined by the last one specified.

You can use “ls -lo” to see the flags of existing files.

Note that the ability to change certain flags is dependent on the current kernel securelevel setting. See security(7) for more information on this setting.

The cache bit may be set to enable swapcache(8) data caching. The superuser flag, noscache may be used to disable swapcache(8) data caching and overrides the user flag.

The flag is recursive but does not cross mount points. Setting it on a top-level directories or mount point will automatically apply the flag to the entire subtree or until a mount point is hit. You may have to refresh the namecache with a dummy find(1) command after changing the flag in a top level directory. You do not have to recursive set the flag with chflags -R and, in fact, we do not recommend it under any circumstances. Filesystems which do not support flags generally have a cache mount option to enable swapcache operation on the mount.

If you intend to use swapcache data the vm.swapcache.use_chflags sysctl determines whether the chflags flags are used or not. If turned off and vm.swapcache.data_enable is turned on, data caching is turned on globally and the file flags are ignored. If use_chflags is turned on along with data_enable then only subtrees marked cacheable will be swapcached.

You would typically want to enable the cache on /usr, /home, and /bin and disable it for /usr/obj. Alternatively if you want to cache NFS mounts (where chflags doesn't work), you can set the flag on some parent directory, possibly even the root (/) itself, and then selectively disable it in places where you don't want it.

This only applies to data caching. Meta-data caching is universal when enabled.

The chflags utility exits 0 on success, and >0 if an error occurs.

ls(1), chflags(2), stat(2), fts(3), security(7), symlink(7), swapcache(8)

The chflags command first appeared in 4.4BSD.

Only a limited number of utilities are chflags aware. Some of these tools include ls(1), cp(1), find(1), install(1), dump(8), and restore(8). In particular a tool which is not currently chflags aware is the pax(1) utility.

May 11, 2016 DragonFly-5.6.1