I am not sure of the internals of implementation, but in my mind 'tar' should never overwrite a file unless with explicit permission (possibly with an -f flag). That way whether arguments were passed in the wrong order or a user tries to create an archive when it already exists, it should simply fail and complain.
I don't know if the problems are technical or due to backward compatibility. Best On Mon, Sep 23, 2013 at 7:53 PM, Connor Behan <connor.be...@gmail.com>wrote: > On 23/09/13 02:16 AM, Joerg Schilling wrote: > > Pulkit Bhuwalka <pulkit.bosc...@gmail.com> wrote: > > > >> Hi, > >> > >> This is to report an issue that I have run into while using tar. > >> > >> *Issue* - tar destroys file when arguments are passed in wrong order > >> leading to loss of data. > >> > >> *Correct tar order* - tar -cvzf "archive_file_name" > "file_to_be_archived" > >> > >> *Order actually passed* - tar - cvzf "file_to_be_archived" > >> "archive_file_name" > >> > >> tar ignores the fact that the "file_to_be_archived" exists and simply > >> overwrites it, and then crashes out complaining that "archive_file_name" > >> doesn't exist. > > ....A problem that is known since before GNU tar exists... > > > > This is typical "tar" behavior and this is why "star" did never allow > this in > > case it was called as "star". When keeping compatibility with the SUSv2 > standard, > > I see no easy way to work around the problem. > > > > Jörg > > > What about the patch I just sent? It would make it slightly harder to > trigger this problem. The relevant part of the SUSv2 standard is the > line that says archives are written from the beginning instead of after > the last file, right? I think the patch still follows that by > overwriting existing archives as long as it can dump a file that exists. > > -- Pulkit
