brew which -- derefernce homebrew's symlinks.

brew-which

#!/usr/bin/env sh # "brew which" -- derefernce paths for homebrew symlinks.
                  # "brew exec" -- exec these instead of printing/returning.

# G. Nixon 2014. Public domain or license of your choice; no warranty, etc.

iam=$(echo "$(basename "$0")" | cut -c6-10); cellar="$(brew --prefix)"

bin=$cellar/bin
optbin=$cellar/opt/bin

## Option parse.
for what; do case $1 in
  -o | --opt*) OPT=1 && shift ;;
  -s | --silent) SILENT=1 && shift ;;

# To do: find unlinked bins. Implement as... -a ? (Changes the meaning.) -u?
  -a | --all) echo "brew $iam: -a flag is yet unimplemented." >&2 && exit 1 ;;

## Homebrew bug. brew does not pass -h | --help | help on to subcommands.
# -h | --help) echo 'Like $iam, but for path in Cellar.'      >&2 && exit 1 ;;
  -h | --*elp) echo "Like $iam, but for path in Cellar."      >&2 && exit 1 ;;

  '*') continue ;;
esac; done


## Work through a shell glob or multiple named arguments.

for what; do what="$(basename "$what")"

  which="$(command -v "$what")"
  binwhich="$bin/$what"
  optbinwhich="$optbin/$what"

  [ -x "$which" ]  && [ -x "$binwhich" ] && # Executable in path and prefix.
  [   -"$which"-    =    -"$binwhich"- ] || exit 1 # ...and they're the same.

  cellarwhich="$(echo "$(readlink "$which")" | sed "s|^\.\.|$cellar|")"
  whichwhat=$cellarwhich

  [ -$OPT-     =  -1- ] && whichwhat=$optbinwhich     # Override for -o flag.
  [ -x "$cellarwhich" ] || exit 1                     # Double check.

  [ "$iam" = "exec" ] && exec $whichwhat ||
    [ -$SILENT-  =  -1- ] || echo "$whichwhat"
done