Adam Robertson shared a comment of this post/conversation

Mon, 27 Jun 2022 17:00:32 -0700

I am looking for advice on the proper way to run backup software in Linux. I've started using iDrive and it is reporting a bunch of files that it can't backup because it lacks permissions. It is running under my account and, without elevation, my account does not have permission to read those files. I looked to see how my soon-to-be-previous backup solution, SpiderOak, handled it only to discover it also isn't backing up those files, but I didn't know until now.

The 2 obvious possibilities are to run the backup service as root, which sounds scary or to make a new backup user specifically for this purpose and grant it lots of read permissions (which may not be as easy as it sounds, as I've never totally groked Linux file permissions when it comes to multiple users/groups).

Adam Robertson

Mon, 27 Jun 2022 18:29:40 -0700

...not sure how or what software is running for these backups, but one possible solution:

you can mount a folder on your linux system using bindfs that will mount the folder as a different user but give that backup user permissions for that folder. so if you had a user called backup, and the thing you are backing up is owned by root

sudo apt install bindfs
mkdir -p /home/backup/thefoldertobackup
chown -R backup:backup /home/backup/thefoldertobackup

sudo gedit /etc/fstab
##add this entry to your fstab file:
bindfs#/the/folder/to/backup /home/backup/thefoldertobackup fuse force-user=backup,force-group=backup,create-for-user=root,create-for-group=root,create-with-perms=0770,chgrp-ignore,chown-ignore,chmod-ignore 0 0

then mount that using
sudo mount /home/backup/thefoldertobackup

this leaves open the possibility to write a bash script that:

mounts the folder
runs the backup utility
unmounts the folder

Marshall Sutherland

Tue, 28 Jun 2022 04:59:44 -0700

Hmm, interesting. For Linux, iDrive is, in part, managed by a collection of scripts. I don't know, however, if those are just for user-managed things or is the automated system uses them as well. That certainly leads to the possibility that such changes could be introduced there.

I do have a ticket open with their support asking for advice, as well.

I seem to have fixed a large part of the problem. One of the folders in question contained email messages for my mail server. At some point permissions changed, allowing backup of email before a certain date. I changed permissions such that those older permissions applied across the board. I'll need to check and see if the more restrictive permissions are still being applied to new messages.

Adam Robertson

Tue, 28 Jun 2022 08:28:21 -0700

I use the above method to mount the /var/www folder on my webservers to my regular user directory at /home/me/www

..works great and solves all the permissions issues I would have while editing website files.

There are a few other cases where I use it as well for random permission issues. It is a good tool to have in the box

Cyborg 2-A ✅

Tue, 28 Jun 2022 20:44:32 -0700

Sudo is hella boring go full-on su

Marshall Sutherland

Mon, 04 Jul 2022 10:47:33 -0700

I was able to solve most of the issues by adding myself (which the backup service is currently running as) to some additional groups.

The problem child was the email server. it has folders of files with only owner permissions. It doesn't honor my attempts to set default permissions for the folder. As a hack, I made a cron job to run before the backup setting group read permissions.