Since the LSI-Unix system does not support pipes, the shell has been modified to simulate pipes through the use of disk files. When a command line which requires the use of a pipe is detected, a disk file is created and opened for reading and writing. The file is immediately unlinked, so that the name is available for another pipe right away. The file is called '.__pf'. Hopefully this name will not conflict with any user file names. Thus, the symbol '|' in a shell command line becomes equivalent to \&'> .__pf ; < .__pf'. The command: % foo ^ goo translates into: % foo > .__pf ; goo < .__pf The process writing on the pipe writes everything into the file, and when it exits, the reader process is swapped in. It reads what the writer has written on the pipe file. The only danger in this type of implementation is due to the limitation of space on the floppy disks. A very large amount of information going through a pipe could fill up the disk. Except for this, the fake pipe code is transparent to the user.