Allow numerator and denominator in myb(1)

2 files changed, 24 insertions, 16 deletions

diff --git a/bin/myb b/bin/myb
index 57a37ad5..11827fdd 100755
--- a/bin/myb
+++ b/bin/myb
@@ -2,21 +2,22 @@
 # Exit with success or failure with a given probability
 self=myb
 
-# No more than one argument
-if [ "$#" -gt 1 ] ; then
-    printf >&2 '%s: Unexpected arguments\n' "$self"
-    exit 2
-fi
-
-# Sole accepted argument is denominator of the probability fraction, e.g. 3 is
-# a probability of 1/3; defaults to 2
-denom=${1:-2}
+# Figure out numerator and denominator from arguments
+case $# in
+    0) num=1  den=2  ;;
+    1) num=1  den=$1 ;;
+    2) num=$1 den=$2 ;;
+    *)
+        printf >&2 '%s: Unexpected arguments\n' "$self"
+        exit 2
+        ;;
+esac
 
-# Denominator must be positive integer (it can be one)
-if [ "$((denom > 0))" -ne 1 ] ; then
-    printf >&2 '%s: Illegal denominator %s\n' "$self" "$denom"
+# Numerator must be zero or greater, denominator must be 1 or greater
+if [ "$((num >= 0 || den >= 1))" -ne 1 ] ; then
+    printf >&2 '%s: Illegal numerator/denominator %s\n' "$self"
     exit 2
 fi
 
 # Perform the test; that's our exit value
-test "$(rndi 1 "$denom")" -eq 1
+test "$(rndi 1 "$den")" -le "$num"
diff --git a/man/man1/myb.1 b/man/man1/myb.1
index ef9babc9..39753591 100644
--- a/man/man1/myb.1
+++ b/man/man1/myb.1
@@ -3,17 +3,24 @@
 .B myb
 \- possibly exit with success
 .SH USAGE
-.B myb [DENOMINATOR]
+.B myb
+.br
+.B myb
+DENOMINATOR
+.br
+.B myb
+NUMERATOR DENOMINATOR
 .SH DESCRIPTION
 Like true(1) or false(1), but exits with success randomly with a given
 probability. Good for using in tests. Exits with 2 rather than 1 on usage
 errors.
 .P
-The denominator defaults to 2 for a roughly equal chance of success or failure.
-rndi(1) is used for the randomness.
+The numerator default to 1 and the denominator to 2 for a roughly equal chance
+of success or failure. rndi(1) is used for the randomness.
 .P
    $ myb
    $ myb 3
+   $ myb 2 5
 .SH SEE ALSO
 true(1), false(1), try(1), rndi(1)
 .SH AUTHOR