I have a text file with over 10,000 lines, each line have a word that starts with the **CDID\_** followed by 10 more characters with no spaces as below:

```
a <- c("Test CDID_1254WE_1023 Sky","CDID_1254XE01478 Blue","This File named as CDID_ZXASWE_1111")

```

I would like to extract the words that start with **CDID\_** only to make the lines above look like this:

```
CDID_1254WE_1023
CDID_1254XE01478
CDID_ZXASWE_1111

```