varnishlog output column meaning

Poul-Henning Kamp phk at
Sun Mar 22 10:08:55 CET 2009

In message <ca6364050903220201t1f50f65btd5b4904f5703f735 at>, Tung 
Nguyen writes:
>Hey guys,
>In the the varnishlog output
>Where can I find out more info on what the columns mean,
>So what does the 7 vs 10 mean in the first column?
>What does the b vs c mean in the second column?

The first column is a magic number for each transaction.

This is what allows you collect all the messages that
belong to the same transaction.

For the time being, it is also the file descriptor number
of the socket, but this is not guaranteed to always be the

The 'b' means "backend transaction, and 'c' client side

> 7 VCL_return   c pass
>10 BackendOpen  b default 57141 3000
> 7 Backend      c 10 default default
>10 TxRequest    b HEAD

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
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