difference between regular file and pipe file in unix
Unix file types These named pipes are special files that can exist anywhere in the file system. These named pipe special files are made with the command mkfifo as in mkfifo mypipe.
printf format string "Printf" is the name of the most-used C output function, and stands for "print formatted". Printf format strings are complementary to scanf format strings, which provide formatted input (parsing). In both cases these provide simple functionality and fixed format compared to more sophisticated and flexible template engines or parsers, but are sufficient for many purposes.