From cd3e8631255561d8ab21352b8cb691c05ca47fcb Mon Sep 17 00:00:00 2001
From: Tom Ryder <tom@sanctum.geek.nz>
Date: Fri, 12 Feb 2016 16:53:20 +1300
Subject: Add try(1) and maybe(1)

---
 bin/maybe | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100755 bin/maybe

(limited to 'bin/maybe')

diff --git a/bin/maybe b/bin/maybe
new file mode 100755
index 00000000..2110a959
--- /dev/null
+++ b/bin/maybe
@@ -0,0 +1,79 @@
+#!/usr/bin/env bash
+
+#
+# maybe(1) -- Like true(1) or false(1); exit with either success or failure
+# randomly. Good for basic testing, but doesn't use precise probabilities, just
+# fractions of RANDOM's limit. Exits with 2 on usage errors so you can tell the
+# difference.
+#
+# -h gives help, -v gives you stdout specifying success or failure.
+#
+# Author: Tom Ryder <tom@sanctum.geek.nz>
+# Copyright: 2016
+#
+self=maybe
+
+# Print usage information
+usage() {
+    printf '%s: usage: %s [-hv] [-d DENOMINATOR]\n' \
+        "$self" "$self"
+}
+
+# Flag for whether to print diagnostics to stdout or not
+declare -i verbose
+verbose=0
+
+# Denominator of the probability fraction, e.g. 3 is a probability of 1/3;
+# defaults to 2
+declare -i denom
+denom=2
+
+# Process options
+while getopts 'hvd:' opt ; do
+    case $opt in
+
+        # -h: Print help
+        h)
+            usage
+            exit 0
+            ;;
+
+        # -v: Print diagnostics to stdout
+        v)
+            verbose=1
+            ;;
+
+        # -d: Set the denominator of the probability fraction
+        d)
+            denom=$OPTARG
+            ;;
+        
+        # Unknown option
+        \?)
+            usage >&2
+            exit 2
+            ;;
+    esac
+done
+shift "$((OPTIND-1))"
+
+# If there are any non-option arguments or our denominator isn't a positive
+# integer, we're being abused and we won't put up with it
+if (($#)) || ! ((denom > 0)) ; then
+    usage >&2
+    exit 2
+fi
+
+# Perform the test and print/exit appropriately
+((verbose)) && printf '%s: Testing with probability 1/%u ... \n' \
+    "$self" "$denom"
+if ((RANDOM < 32767/denom)) ; then
+    ((verbose)) && printf '%s: %s\n' \
+        "$self" 'Success!'
+    exit 0
+else
+    ((verbose)) && printf '%s: %s\n' \
+        "$self" 'Failure!'
+    exit 1
+fi
+
-- 
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