That is not the reason at all. In fact you should read about (POSIX basic) regular expressions, because you obviously don't correctly understand how they work:

The asterisk ("*") makes the previous expression optional, but it doesn't match anything in itself. It means "zero or more occurrences of what comes before". Here is an example:

The regular expression "abcd" matches a fixed string, "a", followed by "b", followed by "c", followed by "d". Now, if you change it to "abc*d" its meaning changes to: "a", followed by "b" followed by zero or more occurrences of "c", followed by "d". Here is an example list of strings that would be matched by this expression:

"abd"
"abcd"
"abccd"
"abccccccd"
etc.

Now, in light of this, read your regexp again:

Code:

s:.*<*mis>...

What you did by inserting the "*" after the "<" was to make the "<" optional. Instead of exactly one "<" you now match any number of "<", including zero (that makes it optional). But what you want is to match the "<", then anything that might precede a ":" including the ":" itself. To phrase it differently: a "<", then zeror or more occurrences of "something, followed by a ":", then what you already matched.

So, let us take you original regexp:

Code:

<mis>

and change it to the specification above. First: something, followed by a ':" - or, more robustly, any number of any character save for a ":", followed by a ":" is:

Code:

[^:]*:

Let us put that in:

Code:

<[^:]*:mis>

Next, we need "zero or more" occurrences of this whole group" and therefore we need to first group it to be able to address it with a single asterisk, hence:

Code:

<\([^:]*:\)*mis>

Note, that groups are numbered automatically, so you may need to replace "\1", "\2", etc. in your replacement string with other numbers maybe.

On a side note: you don't need the grep at all because sed can do that itself:

Change:

Code:

 grep 'pName="vin'  temp.txt | sed -n 's:.*<mis>\(.*\)</mis>.*<seg>\(.*\)</seg>.*:\1\,\2:p'

to

Code:

sed -n '/pName="vin/ s:.*<mis>\(.*\)</mis>.*<seg>\(.*\)</seg>.*:\1\,\2:p'

I hope this helps.

bakunin