Apply runtime shebanging to POSIX shell

1 files changed, 36 insertions, 0 deletions

diff --git a/games/dr.sh b/games/dr.sh
new file mode 100644
index 00000000..e1db163d
--- /dev/null
+++ b/games/dr.sh
@@ -0,0 +1,36 @@
+#!/bin/sh
+# Roll D&D-style dice in a ndn+n formula, e.g. 10d6+2
+
+# Need exactly one argument
+[ "$#" -eq 1 ] || exit 2
+
+# Arcane string chopping
+n=1 a=0
+nd=${1%+*}
+d=${nd#*d}
+[ "${nd%d*}" != "" ] && n=${nd%d*}
+[ "${1#*+}" = "$1" ] || a=${1#*+}
+
+# Check number of roles and addendum make sense
+[ "$((n > 0 && a >= 0))" -eq 1 ] || exit 2
+
+# Check this is a real die you can actually roll
+case $d in
+    4|6|8|10|12|20) : ;;
+    *) exit 2 ;;
+esac
+
+# Roll the dice the appropriate number of times using rndi(1df)
+i=0 t=0
+while [ "$i" -lt "$n" ] ; do
+    seed=$(rnds)
+    r=$(rndi 1 "$d" "$seed")
+    t=$((t + r))
+    i=$((i + 1))
+done
+
+# Add the addendum
+t=$((t + a))
+
+# Print it
+printf '%u\n' "$t"