For bind mounts and without arguments, df only outputs the statistics for that device with the shortest mount point name in the list of file systems( mtab), i.e., it hides duplicate entries, unless the -a option is specified.
What does bind mount mean?
Can you give example for bind mounts and without arguments?
What does it by "df only outputs the statistics for that device with the shortest mount point name in the list of file systems( mtab), i.e., it hides duplicate entries"?
Thanks.
Google 'bind mount' first hit right here on Stack What is a bind mount?
An example of df without arguments is df. df /home has argument /home; df -h /dev/adisk has one argument -h which is an option or flag and another argument /dev/adisk which is not. df has no arguments and thus is 'without arguments'; another phrasing is 'with no arguments'.
df with no arguments -- or more exactly, with no non-option arguments -- lists the filesystems currently known to the system, whereas if you do give a non-option argument (or several) it selects (or tries to) that (or those) specific filesystem(s). But there can be many bind mounts that are all actually the same filesystem and thus have the same filesystem information, so there seems little point to listing all of them, and 'unless you specify the -a option' it only lists one of these 'duplicates', namely the one 'with the shortest mount point name'.
