Write a Makefile.
Add octal escape support to echo.
Rework yes(1) to buffer input. This achieves greater throughput per system call.

Write the following utilities:
 ar
 at/atd
 basename
 batch(?)
 bc
 cal
 cat (done)
 chgrp
 chmod
 chown
 cksum
 cmp
 comm
 compress(?)
 cp
 crond/crontab
 csplit
 cut
 dd
 df
 diff
 dirname
 du
 ed/x
 expand(?)
 expr
 file
 find
 fold
 fuser
 grep
 head
 iconv
 id
 join
 kill
 link(?)
 ln
 locale
 localedef
 logname
 lp(?)
 ls
 mesg
 mkdir
 mkfifo
 mknod
 mktemp
 more
 mv
 newgrp(?)
 nice
 nl
 paste
 pathchk(?)
 pax
 printf
 ps
 pwd
 renice
 rm
 rmdir
 sed
 sh
 sleep
 sort
 split
 strings
 tabs
 tail
 talk(?)
 tee
 test
 touch
 tput
 tr
 tsort
 uname
 uncompress(?)
 unexpand
 uniq
 wc [in progress]
 who
 write(?)
 xargs