bash one-liners with multiple pipes

[daniel]

On May 11, 2004 12:55 pm, G. Matthew Rice wrote:
> Henry Spencer <henry-lqW1N6Cllo0sV2N9l4h3zg at public.gmane.org> writes:
> > What you *can* do, possibly at some cost in convenience, is try to roll
> > all the output processing into a single program.  In particular, note
> > that awk can do anything that grep and sed can do, so it might be
> > possible (if a little cumbersome) to just do "tail | awk".
>
> It doesn't solve the buffering problem but:
>
>          tail -f /some/log | awk '$7 !~ /\.(gif|png|css|jpg)/ {
>                  sub("&requestUrl=.*", "", $7);
>                  print $1, $7
>                 }'
>
> Should do it and it fixes a potential bug in his earlier example.
> The bug being that the first field [$1] is probably IP addresses but could
> also be domain names [such as i.am.a.gif.com ;)].

kickass.  thanks so much.  that's exactly what i'm looking for.  i'll have to 
alias this as "tailblog" or something.

> Even with fflush in awk, I still get the buffering.
>
> However, there's a bigger potential problem.  Is his version of tail going
> to notice when his log file gets truncated and/or moved out of the way?
> Something to test for, at least.

i'm not worried about this since (a) i don't rotate my logs and (b) it's just 
for when i feel like tailing it.  if for some reason i decided to rotate the 
log, i'd just re-run the script.

thanks so much.

-- 
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