Back up and restore file permissions

Question

Is there a way to back up and restore file ownership and permissions (the things that can be changed with chown and chmod)?

You can do this in Windows using icacls.

What about access control lists?

Solution 1

You can do this with the commands from the acl package (which should be available on all mainstream distributions, but might not be part of the base installation). They back up and restore ACL when ACL are present, but they also work for basic permissions even on systems that don't support ACL.

To back up permissions in the current directory and its subdirectories recursively:

getfacl -R . >permissions.facl

To restore permissions:

setfacl --restore=permissions.facl

Solution 2

I'm not aware of anything "off the shelf" that would do this. Here's a starter script for you, though, that will handle basic permissions. It does not handle ACLs of any description - but your Question explicitly excludes those. (It will also fail on pathological filenames - those starting with whitespace, or containing non-printable characters.)

Save the permissions

find * -depth -exec stat --format '%a %u %g %n' {} + >/tmp/save-the-list

Restore the permissions

while read PERMS OWNER GROUP FILE
do
    chmod "$PERMS" "$FILE"
    chown "${OWNER}:${GROUP}" "$FILE"
done </tmp/save-the-list

Comments

[Admin]

It would help if you stated which distro you are using, as different distros use different package managers.

[Admin]

@garethTheRed, does it also depend on the fs being used, or just the distro?

[Admin]

I doubt it would depend on the filesystem.

[roaima]

Hmm. I really need to read up on ACLs.

[leeand00]

In the generated file, are they relative to a directory too?

[Gilles 'SO- stop being evil']

@leeand00 Yes, the generated file always uses relative file names.

[kittygirl]

@Gilles,based on unix.stackexchange.com/questions/364517/… setfacl files then cannot chmod again,maybe will cause conflict?

[kittygirl]

do you mean ACL will also fail on pathological filenames?

[Gilles 'SO- stop being evil']

@kittygirl I have no idea what you're asking. What does “setfacl files then cannot chmod again” mean? What does this have to do with unix.stackexchange.com/questions/364517/… ? What conflict?

[roaima]

@kittygirl I didn't include any processing of ACLs in the scriptlet because the OP had explicitly excluded them from the requirements. You can add what you like, bearing in mind that the code isn't particularly robust (see the comment describing pathological filenames).

[kittygirl]

@Gilles,consider ACL is not respected by other linux function like cp, I am afraid of using setfacl.

[kittygirl]

@Gilles,for the files only defined by chmod and chown,can getfacl -R . >permissions.facl and setfacl --restore=permissions.facl get the origin permission of these files?

[Gilles 'SO- stop being evil']

@kittygirl Yes.

[kittygirl]

@Gilles,does it work for filenames starting with whitespace, or containing non-printable characters?

[Gilles 'SO- stop being evil']

@kittygirl Yes, including newlines.

[kittygirl]

I found a problem:cannot find .htaccess,gitignore...

[kittygirl]

@Gilles,there's big problem(maybe bug):run setfacl by root,cannot change a file like -rw-r--r-- 1 root root,

[Gilles 'SO- stop being evil']

@kittygirl I don't understand your comment. When run by root, setfacl can change the permissions for any file.

[kittygirl]

@Gilles,actually I found a bug.When you run by root, you cannot change -rw-r--r-- 1 root root to -rw-r--r-- 1 usernotexistinyourmachine apache.Normally,if username not exist,will be replaced by userid like 1001.But if owner is root, cannot change to 1001

[Gilles 'SO- stop being evil']

@kittygirl Uh? Why not? Of course notexistuser has to exist. If you request to make a file owned by a user but you give an invalid user name, then the request is rejected, this is the correct behavior. Restoring won't invent a user ID for you, you have to restore the user account before restoring the files.