Week 2, part 2: bash solution

2 files changed, 61 insertions, 0 deletions

diff --git a/challenge-002/abigail/README.md b/challenge-002/abigail/README.md
index bb5cb18c8f..83153f6088 100644
--- a/challenge-002/abigail/README.md
+++ b/challenge-002/abigail/README.md
@@ -37,6 +37,7 @@ one number per line. Programs will use an option, -t (to base 35), or
 
 ### Solutions
 * [AWK](awk/ch-2.awk)
+* [Bash](bash/ch-2.sh)
 * [C](c/ch-2.c)
 * [Lua](lua/ch-2.lua)
 * [Node](node/ch-2.js)
diff --git a/challenge-002/abigail/bash/ch-2.sh b/challenge-002/abigail/bash/ch-2.sh
new file mode 100644
index 0000000000..006c46a8d6
--- /dev/null
+++ b/challenge-002/abigail/bash/ch-2.sh
@@ -0,0 +1,60 @@
+#!/bin/sh
+
+#
+# See https://theweeklychallenge.org/blog/perl-weekly-challenge-002
+#
+
+#
+# Run as: bash ch-2.sh < input-file
+#
+
+set -f
+
+printf -v ord_0 %d "'0"
+printf -v ord_A %d "'A"
+
+while getopts "ft" opt
+do  case "${opt}" in
+        f) action=from ;;
+        t) action=to   ;;
+    esac
+done
+
+function from_base_35 () {
+    local in=$1
+    local ord
+    local char
+    base_10=0
+
+    for ((i = 0; i < ${#in}; i ++))
+    do  ((base_10 = 35 * base_10))
+        char=${in:$i:1}
+        printf -v ord %d "'$char"
+        if [[ $char =~ [0-9] ]]
+        then ((base_10 = base_10 + ord - ord_0))
+        else ((base_10 = base_10 + ord - ord_A + 10))
+        fi
+    done
+}
+
+function to_base_35 () {
+    local in=$1
+    base_35=""
+
+    while ((in > 0))
+    do  ((rem = in % 35))
+        ((in  = in / 35))
+        if ((rem > 9))
+        then printf -v char "\x$(printf %x $((ord_A + rem - 10)))"
+        else char=$rem
+        fi
+        base_35=${char}${base_35}
+    done
+}
+
+while read line
+do   if [[ "$action" = from ]]
+     then from_base_35 $line; echo $base_10
+     else to_base_35   $line; echo $base_35
+     fi
+done