logfile - memory-based append-only circular storage buffer logfile [ -size ] file Logfile creates a name at file (the containing directory must already exist). Each write to file appends the written data up to a maximum of size bytes; subsequent writes erase the existing data in a circular fashion. A read from file will return any currently stored data, if any; if there is none, then it will block until more data becomes available. Multiple readers will receive the data independently of one another. If a writing process is consistently producing data faster than a reading process, then the data read will have some bytes elided; a write is never blocked. /appl/cmd/logfile.b wm-logwindow (1), sys-file2chan (2) Restrictions on sys-file2chan (2) mean that the logfile process will not terminate automatically when its file is removed or unmounted.

There is no indication to a reader of any missing data.

It is not possible to do a non-blocking read of the log file.