[kwlug-disc] tar question regarding leading "/"

[Ronald Barnes]

I'm having issues with `tar` that I don't understand.


I'm trying to backup several files / folders of mailman resources, but 
am getting errors on *one* of them.

(I hope the following formatting is legible.)


The 2 sample files, which exist:

# ls -l /etc/apache2/sites-available/mailman2.conf 
/lib/systemd/system/mailman.service
-rw-r--r-- 1 root root 4793 2021-05-02 14:00 
/etc/apache2/sites-available/mailman2.conf
-rw-r--r-- 1 root root  401 2018-06-23 09:14 
/lib/systemd/system/mailman.service


The tar command changes directory to "/" then runs, so path names do not 
get leading "/" stripped and the associated message doesn't appear:

# tar -v  --directory=/ -pjcf /tmp/mailman-test.tar 
lib/systemd/system/mailman*  etc/apache2/sites-available/mailman2.conf

The error message:

tar: lib/systemd/system/mailman*: Cannot stat: No such file or directory
etc/apache2/sites-available/mailman2.conf
tar: Exiting with failure status due to previous errors


It worked on the apache file, not the systemd file.


If I run it with a leading "/" on the systemd file, this is the output:

# tar -v  --directory=/ -pjcf /tmp/mailman-test.tar 
/lib/systemd/system/mailman*  etc/apache2/sites-available/mailman2.conf
tar: Removing leading `/' from member names
/lib/systemd/system/mailman.service
tar: Removing leading `/' from hard link targets
etc/apache2/sites-available/mailman2.conf


So... now it removes the leading "/" and archives the systemd unit file.


What's going on?



Thanks!

rb