[afnog] EXTRACTING A ZIP FILE ISSUE

[Stephane Bortzmeyer]

On Wed, Oct 21, 2015 at 11:25:08AM +0200,
 Grace <grace.i at ricta.org.rw> wrote 
 a message of 28 lines which said:

> Archive:  xx.bak.zip
> error [xx.bak.zip]:  start of central directory not found;
> zipfile corrupt.

On Unix, zip has options to fix broken files:

       -F
       --fix
       -FF
       --fixfix

The good practice is to start with -F (which is more gentle) and, if
it fails, try with the harsher -FF. (In your case, giving the error
message, you will probably needs -FF.)

>From the manual:

              Fix  the  zip archive. The -F option can be used if some portions of the archive are miss‐
              ing, but requires a reasonably intact central directory.  The input archive is scanned  as
              usual,  but zip will ignore some problems.  The resulting archive should be valid, but any
              inconsistent entries will be left out.

              When doubled as in -FF, the archive is scanned from the beginning and zip scans  for  spe‐
              cial  signatures to identify the limits between the archive members. The single -F is more
              reliable if the archive is not too much damaged, so try this option first.