How can we find specific type of files i.e. doc pdf files present in nested directories.
command I tried:
$ ls -R | grep .doc
If you are more confortable with "ls" and "grep", you can do what you want using a regular expression in the grep command (the ending '$' character indicates that .doc must be at the end of the line. That will exclude "file.doc.txt"):
ls -R |grep .doc$
More information about using grep with regular expressions in the man.