."\ Master source for block : /usr/src/local/man/src/block.rof
.TH BLOCK P "Manual V1.0 for Program V1.0" "Julian H. Stacey" "Julian H. Stacey, http://www.berklix.com"
.\" A4 the cludgy way.
.pl 29.6c
.UC 4
.SH NAME
block \- Filter to output in fixed size blocks.
.SH SYNTAX
.B writing_process | block block_size_in_bytes | reading_process
.SH DESCRIPTION
Filter program, loops till end of file, reading standard input until
block size read, then writes block, then loops again.
.br
Although 
.I block
can be instructed to work in huge blocks, in practice Unix
.I pipe(2) 
limits this (see Limitations below).
.SH EXIT CODE
0 if no errors, else 1.
.SH HOST OP SYSTEM
This utility runs on both Msdos 3.2 & Unix.
.SH COPYRIGHT
Program Copyright Julian H. Stacey, Munich, 6th April 1990
.br
Document Copyright Julian H. Stacey, Munich, 6th April 1990
.so author.jhs
.SH LIMITATIONS
.I block
can be told to write in 64K chunks, but 
.I pipe(2)
only passes data to read process in 4096 byte chunks 
at a time to the next process.
All unixes suffer a similar limitation, though the block size varies.

Under Msdos, 
.I block
would appear pointless as Msdos 3.2 implements pipes by running files
to the completion of each process via temporary files in the root logged directory and drive, however maybe Msdos will improve ?!.
.SH ENHANCEMENTS LATER
BSD4.2 socketpair(2) might avoid the 4096 restriction,
this will be investigated.
.SH FILES
None
.\ End of file