trace-file.bash

trace-file() {
  local cmd="$1"
  local path
  if [[ "$cmd" == /* ]]; then
    path="$cmd"
  elif [[ "$cmd" == */* ]]; then
    path="$PWD/$cmd"
  else
    path="$(type -P "$cmd")"
  fi
  path="${path//"/./"/"/"}"
  if [[ "$path" == "" ]] || ! [[ -e "$path" ]]; then
    printf >&2 '%s: No such file or directory\n' "$cmd"
    return -1
  fi
  printf "%s\n" "${path//"$HOME"/"\$HOME"}"
  local i=0
  while true; do
    i=$(( i + 1 ))
    if [[ "$i" -gt 30 ]]; then
      printf >&2 'recursion limit exceeded\n'
      return -1
    fi
    local step=""
    local next
    if next="$(readlink "$path")"; then
      step=" -> "
    elif [[ "$(file "$path")" == *"ASCII text executable"* ]]; then
      if next="$(grep --max-count=1 --no-messages '^ *exec ' "$path")"; then

        while true; do
          local next_="$(printf %s "$next" | sed -e 's/^ *exec \+//; s/^-[^ a]*a *\+[^ ]\+ \+//; s/^-[^ ]\+ \+//; s/^\([^-][^ ]\+\) .*/\1/')"
          [[ "$next" == "$next_" ]] && break
          next="$next_"
        done
        step="exec"
      fi
    fi
    [[ "$step" == "" ]] || [[ "$next" == "" ]] && break
    [[ "$next" != /* ]] && [[ "$path" == */* ]] && next="$(dirname "$path")/$next"
    next="${next//"/./"/"/"}"
    [[ -e "$next" ]] || break
    printf "  %s %s\n" "$step" "$next"
    path="$next"
  done
  file --brief "$path"
}

$ trace-file ls
/run/current-system/sw/bin/ls
   ->  /nix/store/4g12477iwgjhxhpym3zb34qyp2x3lqjl-coreutils-8.26/bin/ls
   ->  /nix/store/4g12477iwgjhxhpym3zb34qyp2x3lqjl-coreutils-8.26/bin/coreutils
ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /nix/store/a5gvhlwrday3dj8z3v09nr65ngn5jzq3-glibc-2.25/lib/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32, not stripped

$ trace-file firefox
$HOME/.nix-profile/bin/firefox
   ->  /nix/store/0jbqb33sk7f2aqz8y2jzqi2m08yfdd3m-firefox-51.0.1/bin/firefox
   ->  /nix/store/0jbqb33sk7f2aqz8y2jzqi2m08yfdd3m-firefox-51.0.1/lib/firefox-51.0.1/firefox.uFGHd6
  exec /nix/store/fpvnrnj681d53bhm1ymvlh9gx3dl2i32-firefox-unwrapped-51.0.1/bin/firefox
   ->  /nix/store/fpvnrnj681d53bhm1ymvlh9gx3dl2i32-firefox-unwrapped-51.0.1/lib/firefox-51.0.1/firefox
ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /nix/store/amjgskg17wv125v9kahqdfxh8sx6mxgp-glibc-2.24/lib/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32, BuildID[sha1]=f66904e973d2de422b02f2e592c0cefafdf90e3c, stripped