Failed to continue 6.4GB download after 4.2GB already downloaded

Question

I was trying to download a large iso (6,822,254,592 bytes). After 4,423,760,272 bytes (which is more than 4GB, so this isn't a simple 4GB limit problem) my network connection was interrupted for long enough to prevent wget from restarting automatically, so I tried to continue it. But although wget thinks it downloaded the rest of the file, it didn't actually change the file.

HTTP request sent, awaiting response... 206 Partial Content
Length: 6,822,254,592 (6.4G), 2,398,494,320 (2.2G) remaining [application/octet-stream]

100%[++++++++++++++++++++++============>] 6,822,254,592  205.39K/s    ETA 00:00

18:13:09 (191.53 KB/s) - `InstallDVD.iso' saved [6822254592/6822254592]


Q:\>dir
 Volume in drive Q is New Volume
 Volume Serial Number is F273-5A8A

 Directory of Q:\

14/01/2011  22:23     4,423,760,272 InstallDVD.iso
               1 File(s)  4,423,760,272 bytes

I'm using wget 1.10.2, in case this version is known to be buggy.

EDIT: s/resume/continue/g because it was unclear that's what I meant.

Answer 1

There is a feature of wget that supports continuing your download from where you left off. The following portion of wget's man page (from NetBSD) explains the "-c" and "--continue" switches:

-c
--continue
    Continue getting a partially-downloaded file.  This is useful when
    you want to finish up a download started by a previous instance of
    Wget, or by another program.  For instance:

            wget -c ftp://sunsite.doc.ic.ac.uk/ls-lR.Z

    If there is a file named ls-lR.Z in the current directory, Wget
    will assume that it is the first portion of the remote file, and
    will ask the server to continue the retrieval from an offset equal
    to the length of the local file.

...

By default, wget will attempt to download the file from the beginning rather than continue. This is a good thing though because if a smaller file of the same name already existed, then its contents would have extraneous data appended to it which could potentially lead to unexpected problems.