On Mon, Aug 30, 2021 at 09:01:33PM +0200, Rainer Dorsch wrote: > rd@h370:~/tmp.nobackup$ ls -l /tmp/123 > -rw-rw-r-- 1 rd users 0 30. Aug 20:42 /tmp/123
> User ka overwrites it with the content of another file (atomically): > > ka@h370:~$ echo test > 123 > ka@h370:~$ mv 123 /tmp/123 > mv: cannot move '123' to '/tmp/123': Operation not permitted In order to perform this move, ka would first need to unlink the existing /tmp/123 file. ka cannot do that, because the /tmp directory is "sticky". Only "rd" (or root) can do it. > Maybe moving removes a node in /tmp, Yes. You can verify with strace if you're curious enough. > so I am trying to append to the file as a > test: > > -rw-rw-r-- 1 rd users 0 30. Aug 20:35 /tmp/123 > ka@h370:~$ id > uid=1401(ka) gid=1401(ka) Gruppen=1401(ka),20(dialout),21(fax),24(cdrom), > 30(dip),44(video),46(plugdev),100(users),1000(sispmctl) > ka@h370:~$ ls -l /tmp/123 > -rw-rw-r-- 1 rd users 0 30. Aug 20:35 /tmp/123 > ka@h370:~$ echo test >> /tmp/123 > -bash: /tmp/123: Permission denied That one should have worked, due to the secondary group membership. unicorn:~$ sudo touch /tmp/123; sudo chgrp video /tmp/123; sudo chmod 664 /tmp/123 [sudo] password for greg: unicorn:~$ ls -l /tmp/123 -rw-rw-r-- 1 root video 0 Aug 30 15:56 /tmp/123 unicorn:~$ id uid=1000(greg) gid=1000(greg) groups=1000(greg),24(cdrom),25(floppy),27(sudo),29(audio),30(dip),44(video),46(plugdev),108(netdev) unicorn:~$ echo stuff >> /tmp/123 unicorn:~$ It works for me. Is your /tmp a non-Unix file system, or is it mounted with any unusual options?
