UNIX for Dummies Questions & Answers

So I have this sed command below. The content of the tmp.txt file is

Code:

dv01:at01,at05,at02:at04

Code:

sed 's/\:.*\,/\,/g' tmp.txt

Which produces
dv01,at02:at04
and I'm trying to use sed to get me

Code:

dv01,at05,at02

Stripping out the parts leading with ":". My sed is pretty basic, can anyone see at a glance how to fix the above command?

Code:

 echo 'dv01:at01,at05,at02:at04' |sed -r 's/.*:(.*):.*/\1/'
at01,at05,at02

A bit of explanation as to why yours wasn't behaving as desired. First, you don't need to escape the colon or comma which makes it easier to read:

Code:

sed 's/:.*,/,/g' tmp.txt

Regular expression matching is greedy so "colon followed by zero or more characters (.*) followed by a comma will match

Code:

dv01:at01,at05,

(all the way through the last comma) and not the desired dv01:at01.

I prefer to avoid using back references (\1 in the previous example) as they are fairly inefficient. This will work and should be more efficient:

Code:

$ echo "dv01:at01,at05:xxxx,at02:at04" | /usr/bin/sed -r 's/:[^,]*,/,/g; s/:[^,]*$//'
dv01,at05,at02

The code matches a colon, then all characters that are not a comma up to the next comma (just what we want to match) and replaces it with a comma. The last replacement handles the case where the pattern is at the end of the line (no trailing comma).

I do observe that the other example is removing the characters before the colon, and your example indicates that you want everything between colon and comma removed. My example removes the :yyyy from xxxx:yyyy, which is what I assumed you wanted.

Bit obscure and cumbersome 'sed' code:

Code:

echo 'dv01:at01,at05,at02:at04' | sed 's/\([^:]*\):\(.*\),\([^,]*\),\([^:]*\):.*/\1,\3,\4/'

gives output "dv01,at05,at02"

---------- Post updated at 10:58 AM ---------- Previous update was at 10:48 AM ----------

This fails for the agama's input "dv01:at01,at05:xxxx,at02:at04" and it is not at all giving "dv01"

Thanks for all the info, I ended up using agama's example.

But I also found this works pretty good.

Code:

echo 'dv01:at01,at05,at02:at04' | sed 's/:....//g'
dv01,at05,at02

Oops. I hadn't realised that I had left in that :xxxx. I was using that as a test to ensure that if there were such a pattern that it would do the job in addition to the original request.

Yep, that'll work. Your need (something quick to pass over a static set of data, or something that will be used on an ongoing basis) will likely influence what you write in the future. I prefer generic solutions especially if the script will be used on an ongoing basis. Your alternative would be very quickly implemented if you just needed it for a one time shot.