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The shell has had pipes for a while with nothing to pipe *through*, and
an 18-row screen with no way to stop output scrolling off it.
- grep [-vin] PAT [file]: substring match (no regex), stdin or a file,
grep(1)'s exit convention. The other end of the pipe, at last.
- more [file]: pages 17 lines at a time, --More-- bar in white-on-blue,
any key pages, q quits. Counts *screen* rows, so wrapped lines pay
their real cost. Keys come from pollin/pollcon, not stdin, so
`cat big | more` still has a keyboard.
- cp SRC DST: the fs has rm/mkdir but no way to duplicate a file. mv is
this plus rm (there is no rename). Rejects SRC == DST, which would
otherwise truncate the source via O_WRITE before reading a byte.
- nc [-s] HOST PORT: raw TCP. Interactive (START sends the line with a
CRLF, /q quits) or -s to pump stdin and print the reply with its own
wall-clock idle timeout, because the kernel's blocking recv counts
pumps, not seconds. Generalizes what chat/irc hardcode:
`nc towel.blinkenlights.nl 23` works.
sys_pollcon now pumps the link before draining the console ring. The
ring is filled *by* net_pump, so a program that never touches the
network polled a ring nothing would ever fill: host-injected keys
(gbtype/gbdemo) hung `more` forever, and the Game Boy stopped answering
pings for as long as it ran. KGetc already pumps for this reason.
New tools take banks 35-38. Locals over statics in all four: a program's
_DATA starts at $A000, where the shell leaves the command line.
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