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Editorial Team
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Asked: 2026-05-15T14:30:04+00:00

How can I read file from server starting with some offset (Similar behavior to

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How can I read file from server starting with some offset (Similar behavior to wget -c)? What headers I must send to server? What futures must server support?

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  1. Editorial Team

    You should use the Range header in the request. But you may use it only if the server informs you that it accept range request by Accept-Ranges response header.

    This is an example session. Suppose we are interested in getting a part of this picture. First, we send a HTTP HEAD request to determine: a) if the server supports byte ranges, b) the content-length:

    > HEAD /2238/2758537173_670161cac7_b.jpg HTTP/1.1
> Host: farm3.static.flickr.com
> Accept: */*
> 
< HTTP/1.1 200 OK
< Date: Thu, 08 Jul 2010 12:22:12 GMT
< Content-Type: image/jpeg
< Connection: keep-alive
< Server: Apache/2.0.52 (Red Hat)
< Expires: Mon, 28 Jul 2014 23:30:00 GMT
< Last-Modified: Wed, 13 Aug 2008 06:13:54 GMT
< Accept-Ranges: bytes
< Content-Length: 350015

    Next, we send a GET request with the Range header asking for the first 11 bytes of the picure:

    > GET /2238/2758537173_670161cac7_b.jpg HTTP/1.1
> Host: farm3.static.flickr.com
> Accept: */*
> Range: bytes=0-10
> 
< HTTP/1.1 206 Partial Content
< Date: Thu, 08 Jul 2010 12:26:54 GMT
< Content-Type: image/jpeg
< Connection: keep-alive
< Server: Apache/2.0.52 (Red Hat)
< Expires: Mon, 28 Jul 2014 23:30:00 GMT
< Last-Modified: Wed, 13 Aug 2008 06:13:54 GMT
< Accept-Ranges: bytes
< Content-Range: bytes 0-10/350015
< Content-Length: 11
<

    This is a hex dump of the first 11 bytes:

    00000000  ff d8 ff e0 00 10 4a 46  49 46 00                 |......JFIF.|
0000000b

    For more info see the Range header specification in HTTP RFC 2616.

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