[7m Builtin Commands [0;0m

  [I/O]           read   echo 
                  X readarray   X mapfile
  [Run Code]      source .   eval   trap
  [Set Options]   set   shopt
  [Working Dir]   cd   pwd   pushd   popd   dirs
  [Completion]    complete   compgen   compopt   compadjust
  [Shell Process] exec   X logout 
                  umask   X ulimit   X times
  [Child Process] jobs   wait   ampersand &
                  fg   X bg   X disown 
  [External]      test [   printf   getopts   X kill
  [Introspection] help   hash   type   X caller
  [Word Lookup]   command   builtin
  [Interactive]   alias   unalias   history   X fc   X bind
X [Unsupported]   enable
  [Oil Builtins]  cd   X shopt   X env   compatible, and takes a block
                  X fork   X wait        replaces & and (), takes a block
                  X fopen                Many open streams, takes a block
                  X use                  source with namespace, file-relative 
                  X opts                 getopts replacement
                  push                   add elements to end of array
                  repr                   Show debug representation of vars
                  getline                Instead of read -raw :name
                  write                  like echo, but with --, -sep, -end
                  X log   X die          common functions (polyfill)
  [Data Formats]  json   X tsv2   X html   X struct/binary
X [External Lang] BEGIN   END   when (awk)
                  rule (make)   each (xargs)   fs (find)
X [Testing]       check
