Command | You can use the output of one command as the input of another command.
The rpm -qa|grep licq
command uses a pipe character "|" to create a pipe. The pipeline takes the output of the rpm -qa command (including all installed RPM packages on the system) as input to the grep command, which lists RPM packages with the licq character.
Command | provides a way to communicate between two processes.
———————————————————————————————————————————————
> means to enter the result into a file, and before | means as input to the next command, two processes, and > is one process.
But > means rewriting, which means overwriting the original content.
But >> means additional, adding something on the basis of the original content.