I have a ReadyNAS box named storage that I believe is based on Debian.   I can ssh into it as root.   I'm trying to reconfigure the webserver, but I'm running into a file permissions problem that I just don't understand.   I can't do anything with /etc/frontview/apache/apache.pem even as root!  It doesn't appear to have any special permissions compared to other files in the same directory and I can work with those.storage:~# whoami rootstorage:~# cd /etc/frontview/apache/   storage:/etc/frontview/apache# ls -lah apache.pem*         -rw-------    1 admin    admin        4.0k Jul 10  2013 apache.pem-rw-------    1 admin    admin        4.0k Jun  9 05:57 apache.pem.2017-02-04-rw-------    1 admin    admin        1.5k Jun  9 05:57 apache.pem.origstorage:/etc/frontview/apache# touch apache.pem            touch: creating `apache.pem': Permission deniedstorage:/etc/frontview/apache# touch apache.pem.2017-02-04 storage:/etc/frontview/apache# rm -f apache.pemrm: cannot unlink `apache.pem': Operation not permittedWhat is so special about this file that it can't be touched?  I can't delete it.   I can't change the permissions on it.  I can't change the owner of it.The directory seems to be fine.  It has space left, it isn't mounted read-only.  In fact I can edit other files in the same directory.# ls -ld /etc/frontview/apachedrwxr-xr-x    8 admin    admin        4096 Jun  9 05:44 /etc/frontview/apache# df /etc/frontview/apacheFilesystem           1k-blocks      Used     Available Use% Mounted on/dev/hdc1            2015824        504944   1510880   26% /
Permission denied for only a single file in a directory as root user on an ext3 filesystem under RAIDiator OS
files;permissions;root;ext3
I just found the problem.   The immutable attribute was set on that file.   ls doesn't show it.   You need a different command to see it:# lsattr apache.pem*----i--------- apache.pem-------------- apache.pem.2017-02-04-------------- apache.pem.origOnce I remove the immutable bit, I can edit that file:# chattr -i apache.pem# touch apache.pem