diff --git a/documentation/ioc.rst b/documentation/ioc.rst
index d9bfd13..190bef6 100644
--- a/documentation/ioc.rst
+++ b/documentation/ioc.rst
@@ -37,6 +37,20 @@ served by the Integrated PVA server.
     Print information about module versions, target, and toolchain.
     May be requested when reporting a bug.
 
+.. cpp:function:: void pvxs_log_config(const char *config)
+
+    Enable additional :ref:`logconfig` as if more comma separated key=VALUE pairs
+    were appended to the **$PVXS_LOG** environment variable.
+
+    Since UNRELEASED
+
+.. cpp:function:: void pvxs_log_reset()
+
+    Reset logging to defaults.  Negates the effects of **$PVXS_LOG** and later
+    configuration.
+
+    Since UNRELEASED
+
 Adding custom PVs to Server
 ---------------------------
 
diff --git a/documentation/util.rst b/documentation/util.rst
index 68a8137..5e7ff1e 100644
--- a/documentation/util.rst
+++ b/documentation/util.rst
@@ -23,6 +23,11 @@ To enable all logging at full detail. ::
 
     export PVXS_LOG="*=DEBUG"
 
+To enable all internal logging at INFO detail,
+and any entries with the prefix "pvxs.foo*" at DEBUG detail. ::
+
+    export PVXS_LOG="pvxs.*=INFO,pvxs.foo*=DEBUG"
+
 .. doxygenenum:: pvxs::Level
 
 Controlling Logging
diff --git a/ioc/iochooks.cpp b/ioc/iochooks.cpp
index fe50e6d..ae0455d 100644
--- a/ioc/iochooks.cpp
+++ b/ioc/iochooks.cpp
@@ -165,9 +165,17 @@ void testCleanupPrepare()
     resetGroups();
 }
 
-////////////////////////////////////
-// Two ioc shell commands for pvxs
-////////////////////////////////////
+static
+void pvxs_log_config(const char *str)
+{
+    logger_config_str(str);
+}
+
+static
+void pvxs_log_reset()
+{
+    logger_level_clear();
+}
 
 /**
  * Show the PVXS server report.
@@ -456,6 +464,12 @@ void pvxsBaseRegistrar() noexcept {
 
         bool enableQ = enable2();
 
+        IOCShCommand<const char*>("pvxs_log_config", "KEY=VAL,KEY=VAL,...",
+                                  "Append logger configuration.  eg. pvxs_log_config \"pvxs.*=DEBUG\"")
+                .implementation<&pvxs_log_config>();
+        IOCShCommand<>("pvxs_log_clear",
+                       "Reset logger configuration to defaults")
+                .implementation<&pvxs_log_reset>();
         IOCShCommand<int>("pvxsr", "[show_detailed_information?]", "PVXS Server Report.  "
                                                                    "Shows information about server config (level==0)\n"
                                                                    "or about connected clients (level>0).\n")
diff --git a/src/log.cpp b/src/log.cpp
index 46e4952..b3d3afc 100644
--- a/src/log.cpp
+++ b/src/log.cpp
@@ -340,12 +340,8 @@ void logger_level_clear()
     logger_gbl->config.clear();
 }
 
-void logger_config_env()
+void logger_config_str(const char *env)
 {
-    const char *env = getenv("PVXS_LOG");
-    if(!env || !*env)
-        return;
-
     threadOnce<&logger_prepare>();
 
     Guard G(logger_gbl->lock);
@@ -389,6 +385,15 @@ void logger_config_env()
     errlogFlush();
 }
 
+void logger_config_env()
+{
+    const char *env = getenv("PVXS_LOG");
+    if(!env || !*env)
+        return;
+
+    logger_config_str(env);
+}
+
 } // namespace pvxs
 
 namespace pvxs {namespace impl {
diff --git a/src/utilpvt.h b/src/utilpvt.h
index e8ffb81..fd7a261 100644
--- a/src/utilpvt.h
+++ b/src/utilpvt.h
@@ -252,6 +252,9 @@ using aligned_union = std::aligned_union<Len, Types...>;
 } // namespace impl
 using namespace impl;
 
+PVXS_API
+void logger_config_str(const char *env);
+
 inline
 timeval totv(double t)
 {