Q: How do I search for a specific text string in a all files?
A: Say you want to find the string "sysadmin" in all files recursively in the folder /root/files.
# grep -R "sysadmin" /root/files/* > /root/files/sysadmin.txt
Saves all found duplicate lines to the file sysadmin.txt.
# sort -u /root/files/sysadmin.txt > /root/files/sysadmin.deduped.txt
Sorts and removes all duplicate lines, leaving one, then saves to the file sysadmin.deduped.txt.
Sources
https://www.cyberciti.biz/faq/unix-linux-shell-removing-duplicate-lines/