Remove trailing white space with:
for f in *.{h,c}; do sed -i .sed 's/[[:blank:]]*$//' $f; done
(Thanks to Nicolás Wolovick)

Remove puts in favor of printf.
Allow multiple arguments to ls.

cleanup

make ls work on directories

remove _ prefixes

wrap long lines

weird spacing

standardize various * conventions

spacing fixes: no tabs, 2-space indents (for rtm)

i/o redirection in sh
better parsing of sh commands (copied from jos sh)
cat: read from 1 if no args
sbrk system call, but untested
getpid system call
moved locks in keyboard intr, but why do we get

i/o redirection in sh
better parsing of sh commands (copied from jos sh)
cat: read from 1 if no args
sbrk system call, but untested
getpid system call
moved locks in keyboard intr, but why do we get intr w. null characters from keyboard?

show more ...

chdir
cd in shell
nits in mkdir, ls, etc.

user-level programs: mkdir and rm
shell parses arguments (very simplistic)
readme version of README (sh doesn't deal with capital characters)
printf recognizes %c
nicer output format for ls

set size for directories correctly in wdir and mkfs
mkdir
ls shows stat info for each dir entry

start on mkdir
stat

don't print unallocated dir entries

fstat
primitive ls