LOGFILE(4)                                             LOGFILE(4)

     NAME
          logfile - memory-based append-only circular storage buffer

     SYNOPSIS
          logfile [-size] file

     DESCRIPTION
          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.

     SOURCE
          /appl/cmd/logfile.b

     SEE ALSO
          wm-logwindow(1), sys-file2chan(2)

     BUGS
          Restrictions on sys-file2chan(2) mean that the logfile pro-
          cess 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.

     Page 1                       Plan 9            (printed 12/18/25)