find / -name fastjson-1.2.7.jar starts from the root directory, that is, searches the entire disk
find . Search the current directory, including subdirectories
find .-maxdepth 1 Search the current directory, the depth is 1, that is, do not search subdirectories
find ./ -name '*.log'| xargs grep ERROR -l list filenames containing ERROR
find ./ -name '*.log'| xargs grep ERROR List the file names and ERROR information containing ERROR