How trash-put should choose in which trash directory the file should be trashed?
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When user launches::

  $ trash-put file-to-be-trashed

the file can be trashed in:
 1. "home trash" ($XDG_DATA_HOME/Trash)
 2. primary top trash directory ($topdir/.Trash/$uid)
 3. alternate top trash directory ($topdir/.Trash-$uid)

With these rules:
 - Home Trash
    1. when the file is in the same volume of the "home trash" should choose 
       "home trash"
    2. "home trash" should be available for each user
    3. "home trash" if not present should created with no delay
    4. "home trash" can be used as failsafe method, that means:
         when the file is different volume but it fails to use both the top 
         trash directories it chose "home trash"
 - Primary Top Trash Dir
    1. in $topdir/.Trash can be created by an admin
        - should be created by the admin
        - should permit user to create $topdir/.Trash/$uid
        - should not be a symbolic link
        - the $topdir/.Trash/$uid should not writable by others
    2. should be skipped if any of the conditions above is unsatisfied
    3. The $topdir/.Trash/$uid should be automatically created without delay
       if not present
 - Alternate Top Trash dir
    1. Should be created with any delay if needed

EOF
