EVERYTHING FROM THE OTHER REPO

include/dual_rootfs/usr/sbin/add-shell

@@ -0,0 +1,47 @@
+#!/bin/sh -e
+
+if test $# -eq 0
+then
+        echo "usage: $0 shellname [shellname ...]"
+        exit 1
+fi
+
+file="$DPKG_ROOT/etc/shells"
+# I want this to be GUARANTEED to be on the same filesystem as $file
+tmpfile="${file}.tmp"
+
+set -o noclobber
+
+cleanup() {
+	rm -f "$tmpfile"
+}
+trap cleanup EXIT
+
+if ! cat "$file" > "$tmpfile"
+then
+        cat 1>&2 <<EOF
+Either another instance of $0 is running, or it was previously interrupted.
+Please examine ${tmpfile} to see if it should be moved onto ${file}.
+EOF
+        exit 1
+fi
+
+for i
+do
+        REALDIR="$(dirname "$(realpath -m "$i")")/$(basename "$i")"
+        for j in "$i" "$REALDIR"
+        do
+                if ! grep -q "^${j}$" "$tmpfile"
+                then
+                        echo "$j" >> "$tmpfile"
+                fi
+        done
+done
+
+chmod --reference="${file}" "${tmpfile}" || chmod $(stat -c %a "${file}") "${tmpfile}"
+chown --reference="${file}" "${tmpfile}" || chown $(stat -c %U "${file}") "${tmpfile}"
+
+mv -Z "${tmpfile}" "${file}" || mv "${tmpfile}" "${file}"
+
+trap "" EXIT
+exit 0