CommandNotFound

#! /usr/bin/zsh (source)
# ZSH code for CommandNotFound support. Sourced from zshrc, but in a separate
# file so it can be updated without going through the UpdateSettings process.

# Defined as separate functions to ease the use of other precmd() functions in
# ~/.zshrc. Behaviour can be disabled with `unset -f CommandNotFound_preexec`.
function CommandNotFound_preexec() {
   setopt localoptions shwordsplit
   # Trim back to the command itself, chopping off everything until
   # a space, pipe, redirect, semicolon or ampersand.
   command="${1%%[|>< ;&]*}"
   # Our zshrc defines autocd by default, so ignore directory names
   [ -d "$command" ] && command=
   # If you define this variable to point to a tool that works like
   # "kfmclient exec", you can automatically launch a file with its
   # appropriate application just by typing its name. A little hacky, but
   # effective.
   if [ "$OPEN_COMMAND" -a -e "$command" ]
   then
      if ! whence -- "$command" >& /dev/null
      then
         # If it succeeds, suppress ZSH's default "command not found" message.
         $OPEN_COMMAND "$command" && exec 2>/dev/null
         command=
      fi
   fi
   # When there's an environment variable or function definition, a path,
   # or a shell expansion, just forget about it. They probably know what
   # they're doing.
   [ "$command" != "${command%%[\$~=(\\\"\'/]*}" ] && command=""
}

function CommandNotFound_precmd() {
   [ -z "$command" ] && [ "$OPEN_COMMAND" ] && exec 2>&1 # Restore stderr
   if [ $? -ne 0 ] && [ -n "$command" ]
   then
      whence -- "$command" >& /dev/null ||
         CommandNotFound $command
      unset command
   fi
}

# This initialises the list of precmd/preexec functions so the standard
# function names transparently work. It ensures the entries aren't
# duplicated if this file is sourced more than once.
if [ "$precmd_functions" ]
then
   precmd_functions=( "${precmd_functions[@]:#CommandNotFound_precmd}" CommandNotFound_precmd )
else
   precmd_functions=( CommandNotFound_precmd )
fi
if [ "$preexec_functions" ]
then
   preexec_functions=( "${preexec_functions[@]:#CommandNotFound_preexec}" CommandNotFound_preexec )
else
   preexec_functions=(CommandNotFound_preexec )
fi