When I echo into files at some arbitrary locations in Linux, i.e.
echo > /tmp/file, some running processes respond. Is this IPC via file pipe?
Does this mean a running process always open the file to be read? But so, how can the file be written, since the file stream is locked by by its own process?
If you want use a file to communicate with another process, you should have a look at
I’ll report here just the first lines:
NAME fifo - first-in first-out special file, named pipe DESCRIPTION A FIFO special file (a named pipe) is similar to a pipe, except that it is accessed as part of the file system. It can be opened by multiple processes for reading or writing. When processes are exchanging data via the FIFO, the kernel passes all data internally without writing it to the file system. Thus, the FIFO special file has no contents on the file system; the file system entry merely serves as a reference point so that processes can access the pipe using a name in the file system.
I think this is what you need.
Just think to it as a buffer. It must be opened both for reading and for writing by different process. The process who’s reading will be blocked until the writing process doesn’t write on it. When the writing process finish to write, close the file and that is the green light for the reading process to start empty the buffer. It’s a FIFO, so the first line written will be the first line read. Then the writing process can open it again and they start again.
You can create a FIFO with
mkfifo. Have a look to
Answered By – Zagorax