[vox]$ echo foo > zzz
[vox]$ chmod 000 zzz
[vox]$ tar cvf /dev/null zzz
zzz
[vox]$ echo $?
0
[vox]$ tar cvf zzz.tar zzz
tar: zzz: Cannot open: Permission denied
tar: Exiting with failure status due to previous errors
[vox]$ echo $?
2
[vox]$