Searching for files ?

 find command

find   -name aaa.txt    Finds all the files named abcd.txt in the current directory or

  any subdirectory tree.

find / -name vimrc      Find all the files named 'abcd' anywhere on the system.

find /usr/ -name "*abcd*"      

Find all files whose names contain the string 'abcd' which

exist within the '/usr/' directory tree.