um rename to handle piped input

shell/rename.sh

@@ -2,16 +2,31 @@
 
 # Usage:
 
-# > rename 100.md bar
+# > um rename 100.md foo
 # or
-# > rename 100.foo.md bar
+# > um rename 100.foo.md bar
+# or
+# > um last | um rename baz
 
 # is equivalent to:
-# > mv 100.md 100.bar.md
+# > mv 100.md 100.foo.md
 # > mv 100.foo.md 100.bar.md
+# > mv 100.bar.md 100.baz.md
+
+# accept piped input
+# https://unix.stackexchange.com/a/537581
+if [[ ! -t 0 ]]; then
+    FROM=$(cat -)
+    TO=$1
+else
+    FROM=$1
+    TO=$2
+fi
+
+echo from: $FROM to: $TO
 
 # split the args by a newline so that awk reads them as separate "records"
-mvcmd=`echo "$1
-$2" | awk -f $UMBASEPATH/rename.awk`
+mvcmd=`echo "$FROM
+$TO" | awk -f $UMBASEPATH/rename.awk`
 
 mv $mvcmd

shell/test/um.bats

@@ -89,6 +89,21 @@ um_next_awk() {
 + foo'
 }
 
+@test "um rename" {
+    run um rename 001.md blah
+    run ls 001*
+    assert_output '001.blah.md'
+    mv 001.blah.md 001.md
+}
+
+# this doesn't work because bats doesn't handle stdin the way a tty does.
+# @test "um rename piped" {
+#     run um last | um rename gloo
+#     run ls 099*
+#     assert_output '099.gloo.md'
+#     mv 099.gloo.md 099.poo.md
+# }
+
 um_rename_awk() {
     echo "$1
 $2" | awk -f $DIR/../rename.awk