I altered the regex code to replace the first 5 commas instead of the first 4

Congratulations. That means you understood what was going on. Knowing that people learn from what I write, rather than just copy/pasting and moving on, is always a good feeling.

@PeterJones OK, sorry to bother, but new problem. When I import the altered files into Excel with comma as delimiter it creates too many columns when the tweets contain commas themselves. I was thinking what I could do is replace the 6th+ instances of commas (…) in a line with a very uncommon character like “ɤ” and then search/replace that character in excel after the fact. The thing is, I don’t know how to write the Regex code to replace not just the 6th instance, but the 7th, 8th, 9th, etc instances. Thanks for the help!

That’s one good idea. If I were to do it that way, step 1 would be to just replace all commas with ɤ. Step 2 would be your 5-space-to-comma replacement from above.

But since you’re trying to make valid CSV to open in Excel, CSV has a way of putting quotes around a field so that any commas inside will be treated as part of the text, not as a field separator. But that would mean that if you have any text with quotes in it, that will get messed up. But there’s a way around that by escaping the quote by changing any " to "". So my procedure for what I think what you want with your data:

0. Search Mode = regular expression for all of this
1. FIND = "
   REPLACE = "" to escape the quotes
2. FIND = ^(\S+) (\S+) (\S+) (\S+) (\S+) (.*$)
   REPLACE = $1,$2,$3,$4,$5,"$6" to change spaces to commas and to put quotes around the text.

data:

123456786 1999-12-31 23:59:57 -0400 <username> Three! with more spaces
123456787 1999-12-31 23:59:58 -0400 <username> Two! with more spaces
123456788 1999-12-31 23:59:59 -0400 <username> One! with more spaces
123456789 1900-01-01 00:00:00 -0400 <username> Happy Y2K Bug!

• FIND = ^(\S+) (\S+) (\S+) (\S+)\x20
  (I used a \x20, which is equivalent to a space character at the end to make it obvious that there’s something at the end, so you will get it when you copy/paste; if typing the regex, you could just use a space after the last parentheses)
• REPLACE = $1,$2,$3,$4,
• Search Mode = Regular expression

123456786,1999-12-31,23:59:57,-0400,<username> Three! with more spaces
123456787,1999-12-31,23:59:58,-0400,<username> Two! with more spaces
123456788,1999-12-31,23:59:59,-0400,<username> One! with more spaces
123456789,1900-01-01,00:00:00,-0400,<username> Happy Y2K Bug!