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(wget.info)FTP Time-Stamping Internals

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FTP Time-Stamping Internals
===========================

   In theory, FTP time-stamping works much the same as HTTP, only FTP
has no headers--time-stamps must be ferreted out of directory listings.

   If an FTP download is recursive or uses globbing, Wget will use the
FTP `LIST' command to get a file listing for the directory containing
the desired file(s).  It will try to analyze the listing, treating it
like Unix `ls -l' output, extracting the time-stamps.  The rest is
exactly the same as for HTTP.  Note that when retrieving individual
files from an FTP server without using globbing or recursion, listing
files will not be downloaded (and thus files will not be time-stamped)
unless `-N' is specified.

   Assumption that every directory listing is a Unix-style listing may
sound extremely constraining, but in practice it is not, as many
non-Unix FTP servers use the Unixoid listing format because most (all?)
of the clients understand it.  Bear in mind that RFC959 defines no
standard way to get a file list, let alone the time-stamps.  We can
only hope that a future standard will define this.

   Another non-standard solution includes the use of `MDTM' command
that is supported by some FTP servers (including the popular
`wu-ftpd'), which returns the exact time of the specified file.  Wget
may support this command in the future.