Question: It should be a very simple problem, or so I thought.
Here is the text:

```
MSYSID : 00014000 (TC1 Gen2)
PCIE   : x4ab     (neg: x4/x4)
TCID   : d7151210 (344017 @ 07/15/13 12:10)
SLOT   : 1

```

I'd like to match all the string after TCID. 
This regular expression should work:

```
(?<=TCID\s+:\s+).+

```

It has proper lookbehind and matching string, but it doesn't and I don't see why.
Anyone can find a mistake? I was using [regexpal](http://regexpal.com/) to verify it.

Thank you.

Answer: 
`((?<=TCID\s{3}:\s)).+`

The problem is that wildcards don work with look behind.
As wild cards have to be of fixed length.
Have a look at the Python columns [here](http://www.regular-expressions.info/refflavors.html). `TCID\s+:\s(\w.+)$` should work if you can get the captured portion of the match (the `(\w.+)`) and set to match ^$ at line breaks.

I don't believe [Regexpal](http://regexpal.com/) can handle lookbehinds at all (many flavours can't), and Python has a limitation that the lookbehind must be a fixed length. You shouldn't need a lookbehind if you can get the captured portion of the match.