How to grep only selected words from a file?

Question

I need to get a list of all the email addresses from a file.

I was trying to use

grep @ filename

but that returns the entire line.

Is there anyway I can get it to return only the email address and not the whole line?

Answer 1

That's going to depend on the format of the file. For example, let's say the file has

email@example.com stuff you don't want
email2@example.com more stuff you don't want
email3@example.com and more

then awk '/@/{print $1}' would seem to be the obvious answer.

Post an example of the file format if that's not what you've got.

Answer 2

Note that properly matching any valid email address is a deep magic, so if you really want to catch everything with no false positives or negatives, you should use a regex someone else has written. But if you're just looking for a quick grep that is Good Enough, check out the -o option which will show only the matching text.

$ grep -Po '\S+@\S+\.\w+' yourfile.txt

That will catch some simple email addresses, along with some things that are not valid email addresses (like "@@@@.a"). Adjust your regex as appropriate. E.g., this one is more restrictive:

$ grep -Po '[\w+.]+@[\w.]+\.\w+' yourfile.txt

Answer 3

@rbright this solution seems to work. the "-o" option is what I was missing! But I ended up just writing a php script before I got your response.

$handle = fopen("MYFILE.txt","r");

if ($handle) {  
    while (!feof($handle)) {
        $buffer = fgets($handle);

        $pieces = explode(" ",  $buffer);
        foreach($pieces as $piece){
            if( strstr($piece, '@' && $piece != " ")){              
           echo $piece;             
            }
        }   
    }
 fclose($handle);
} 

This is a fast and dirty but it will hold up until there is a @ that is not in a email address which is very unlikely in my situation