fix: commands on SSH hosts run under sh -c, so hosts whose login shell is csh or tcsh list, zip and send files too

internal/agent/sshfs_test.go

@@ -225,3 +225,18 @@ func TestListFolderLink(t *testing.T) {
 		}
 	}
 }
+
+// Commands go to the host as one argument of sh -c, so the user's own login
+// shell (fish, csh) cannot read them its way.
+func TestPosixCommand(t *testing.T) {
+	if got := posix(`if [ -d '/x' ]; then echo ok; fi`); got != `sh -c 'if [ -d '\''/x'\'' ]; then echo ok; fi'` {
+		t.Fatalf("%s", got)
+	}
+}
+
+// csh expands "!" even inside single quotes: it goes out as '\!'.
+func TestPosixCommandBang(t *testing.T) {
+	if got := posix(`ls .[!.]*`); got != `sh -c 'ls .['\!'.]*'` {
+		t.Fatalf("%s", got)
+	}
+}