apt-rdepends(1) clone(?): Recursively lists package dependencies

apt-rdepends.ksh

#!/bin/ksh93
##
## apt-rdepends(1) clone(?): Recursively lists package dependencies
## Copyright (c) 2012 SATOH Fumiyasu @ OSS Technology Corp.
##               <http://www.osstech.co.jp/>
##

set -u
if [ $# -ne 1 ]; then
  echo "Usage: $0 PACKAGE"
  exit 1
fi

pkg="$1"; shift

apt_rdepends_recurse()
{
  typeset pkg="$1"; shift
  typeset rev_pkg="${1-}"
  typeset dep_pkg pkg_tag pkg_tag_value

  apt-cache show "$pkg" \
  |sed -n 's/^Depends: *//p' \
  |tr ',' '\n' \
  |awk '{printf $1; gsub("[-+.]", "_", $1); print " pkg_tag_"$1;}' \
  |while read dep_pkg pkg_tag; do
    eval "pkg_tag_value=\${$pkg_tag-}"
    if [[ -z "$pkg_tag_value" ]]; then
      printf '%-30s %s\n' "$dep_pkg" ## "$rev_pkg"
      eval "$pkg_tag=$dep_pkg"
      apt_rdepends_recurse "$dep_pkg" "$pkg"
    fi
  done
  ;
}

apt_rdepends_recurse "$pkg"