usr: ls -l, df, mv, tail, tee, sleep, help, poweroff

Filling in the core utilities the box was missing:

- ls -l: type, links and size, now that stat() exists. The screen is 40
  columns, so it is "d  1   256 name", not the GNU sprawl. Sizes were
  previously unknowable except one file at a time with wc -c.
- df: blocks and inodes, used and free, on the 32 KiB cart disk.
- mv: no rename syscall, so it is cp + rm - and the copy has to finish before
  the source goes, or a failure loses the file.
- tail [-n N]: no seek syscall, so it streams the input through a ring of N
  lines rather than jumping to the end. N is capped by that ring.
- tee: the missing half of a pipeline - `cat big | tee copy | wc -l`.
- sleep: the thing every script needs; the kernel counts 1/64 s ticks.
- help: lists every command the shell knows, walked out of the kernel's own
  name table. The box previously had no way to tell you what it could do.
- poweroff: the only safe way to stop a gbos that has data on it. The cart's
  battery RAM is written when the emulator exits cleanly, so killing it loses
  the whole filesystem - it comes back "formatted". Found while testing /rc.

1 files changed, 2 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index 53c8f21..de7175b 100644
--- a/Makefile
+++ b/Makefile
@@ -28,7 +28,8 @@ $(BUILD)/%.o: src/%.asm $(INCS) | $(BUILD)
 PROGS  := chello echo true false uname pid cat wc head args \
           ls save rm sh ps kill spin blk mkdir count ptest necho \
           wget chat netd ping nslookup dhcp irc uptime ansi \
-          grep more cp nc httpd ircd
+          grep more cp nc httpd ircd \
+          df mv sleep tee tail help poweroff
 CBLOBS := $(patsubst %,$(BUILD)/usr/%.bin,$(PROGS))
 $(BUILD)/programs.o: $(CBLOBS)