File Attributes

Unix file attributes can be listed with the stat utility.

# stat /some/file
  File: ‘/some/file’
  Size: 13857688196     Blocks: 27066368   IO Block: 16777216 regular file
Device: 2dh/45d Inode: 12331       Links: 1
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Context: unconfined_u:object_r:unlabeled_t:s0
Access: 2018-09-06 17:30:48.650399353 -0600
Modify: 2018-09-01 22:26:44.904672188 -0600
Change: 2020-06-11 15:53:36.225415501 -0600
 Birth: -

Use the following tools to modify:

	Tool	Example
Permissions	chmod <permission>	# chmod 644 file.dat # chmod u+rw file.dat
Ownership	chown / chgrp	## Both # chown user:group file.dat ## Or individually # chown user file.dat # chgrp group file.dat
SELinux Context	chcon -R <context>	# chcon -R unconfined_u:object_r:user_home_t:s0 /home/user/.ssh/
Access Time	touch -a -t YYYYMMDDhhmm.ss	## Set access time to Dec 26 2020 at 1:30:30PM # touch -a -t 202012261330.30 /some/file ## Set a file based on a reference file # touch -a -r reference.ext target.ext
Modify Time	touch -m -t YYYYMMDDhhmm.ss	## Set modification time to Dec 26 2020 at 1:30:30PM # touch -m -t 202012261330.30 /some/file ## Set a file based on a reference file # touch -m -r reference.ext target.ext
Change Time	???

Tasks

Preserve File Ownership/Attributes

If you copied a set of files without preserving any of the attributes, rather than copying the data again, you can rsync again but this time using the archive option (which enables a bunch of other flags including the one for preserving ownership, permissions, and timestamps).

If you're in a rut like I was after recovering data from a tape, you can do something like this:

#!/bin/bash

# Replace files here to the root filesystem, but preserving timestamps
# Eg.  ./etc/fstab gets copied to /etc/fstab, but with timestamps, permissions retained.
find | while read i ; do
        if [ -f $i ] ; then
               touch -a -m -r /$i $i
               chown -v --reference /$i $i
               chmod -v --reference /$i $i

                # Replace source with the local copy I have here
                rm -v /$i
                mv -v $i /$i
        fi
done