Grep-ing from standard error

Sometimes you find yoruself wanting to grep for content that's being sent to standard error instead of standard out. One example is the response header information sent from wget when passing the --server-response parameter.

What you do is to add this at the end of the command you want to grep the output of:

2>&1 >/dev/null

So, to grep on the response HTTP headers returned by wget command, you'd do:

$ wget \
  --quiet \
  --server-response \ \
  2>&1 >/dev/null | \
  grep <what ever you are looking for>

That's it!

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