Bash – Pattern matching across multiple lines

awkbashgrepsed

What is a quick and easy way to validate if the pattern "301 domaname.com 200" is present within BASH when spread across multiple lines of output?

I was using something like the following:

 awk '/301|domain.com|200/'
 pcregrep -M '301|domain\.com|200'

but the order doesn't matter. I'm not sure how to state it so it does. What I thought would work apparently isn't catching the line endings. 

pcregrep -M '301.*domain\.com.*200'

Background:

I'm building a small mod_rewrite server and I need a way to monitor what domains are getting redirected to what destinations.

As a result I'm assembling a small Nagios check script that will handle this for me.

What I have so far is the following:

curl qa-mod-rewrite.domain.com -i -I -L

HTTP/1.1 301 Moved Permanently
Via: 1.1 GREGORY
Connection: close
Proxy-Connection: close
Date: Thu, 14 Nov 2013 16:35:19 GMT
Location: http://qa.domain.com/
Content-Type: text/html; charset=iso-8859-1
Server: Apache/2.2.3 (CentOS)

HTTP/1.1 200 OK
Via: 1.1 GREGORY
Connection: Keep-Alive
Proxy-Connection: Keep-Alive
Content-Length: 56772
Expires: -1
Date: Thu, 14 Nov 2013 16:35:03 GMT
Content-Type: text/html; charset=utf-8
Server: Microsoft-IIS/7.5
Cache-Control: no-cache, no-store
Pragma: no-cache
X-AspNet-Version: 2.0.50727
Set-Cookie: cfcausa.qa#sc_wede=1; path=/
Set-Cookie: ASP.NET_SessionId=i4z1c4ahqoiw13552z413hbs; path=/; HttpOnly
X-Powered-By: ASP.NET

Best Answer

There's scope for false positive there as 301.*domain\.com.*200 would match for instance on:

HTTP/1.1 404 Not found
Content-Length: 3010
X-Pingback: http://blah.domain.com/xmlrpc
Last-Modified: Thu, 14 Nov 2009 19:27:05 GMT

You could be a bit more thorough and write it for instance:

curl -sIL http://qa-mod-rewrite.domain.com |
  tr -d '\r' |
  awk -v RS= '
    NR == 1 && $2 == "301" && /\nLocation: [^\n]*domain\.com/ {redir=1}
    $2 == "200" {end=1}
    END {exit !(redir*end)}'

With variable data:

url=$1
EXPECTED_REDIRECTION=$2
EXPECTED_REDIRECTION_CODE=$3
EXPECTED_TERMINAL_CODE=$4
export EXPECTED_REDIRECTION EXPECTED_REDIRECTION_CODE EXPECTED_TERMINAL_CODE

curl -sIL "$url" |
  tr -d '\r' |
  awk -v RS= '
    BEGIN {
      re = ENVIRON["EXPECTED_REDIRECTION"]
      gsub(/[][^.$+?\\()]/, "\\&",re)
      re = "\nLocation: [^\n]*" re
    }
    NR == 1 && $2 == ENVIRON["EXPECTED_REDIRECTION_CODE"] && $0 ~ re {redir=1}
    $2 == $ENVIRON["EXPECTED_TERMINAL_CODE"] {end=1}
    END {exit !(redir*end)}'
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