Search Disallow: / in robots.txt

Question

I want to search Disallow: / in robots.txt of domains.
I have wrote regex, but it is not working.

if(preg_match("!Disallow:\s*/\s\r\n!i",$string,$disallow_char))
{
  print_r($disallow_char);
}

Following are two test cases.
1)

User-agent: * 
Disallow: /

2)

User-agent: *
Disallow: /product/generate_pdf/40
Disallow: /news/
Disallow: /news/bollards
Disallow: /product/generate_pdf/44
Disallow: /
Disallow: /page_management/insert
Disallow: /glossary/ajax_call/update_words

It should output true for both the cases.

Answer 1

You need to assert that either a newline sequence or the end of the string follows:

echo preg_match('~Disallow:\h*/(?:\R|$)~i', $string)

Explanation :

Disallow:      # 'Disallow:'
\h*            # horizontal whitespace (0 or more times)
/              # '/'
(?:            # group, but do not capture:
  \R           #   '\R' (any Unicode newline sequence) 
 |             #  OR
  $            #   before an optional \n, and the end of the string
)              # end of grouping