From bbfa18d72c34d8710b5f4f3fa1fff54f5248fcc5 Mon Sep 17 00:00:00 2001
From: Kevin Sawatzky <66632997+nuclearkevin@users.noreply.github.com>
Date: Fri, 12 Dec 2025 03:29:43 -0600
Subject: [PATCH] Add a command-line argument for output verbosity (#3680)

Co-authored-by: Paul Romano <paul.k.romano@gmail.com>
---
 docs/source/usersguide/scripts.rst |  1 +
 man/man1/openmc.1                  |  3 +++
 src/finalize.cpp                   |  2 +-
 src/initialize.cpp                 | 13 ++++++++++++-
 src/output.cpp                     |  1 +
 src/settings.cpp                   |  6 ++++--
 6 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/docs/source/usersguide/scripts.rst b/docs/source/usersguide/scripts.rst
index 0879d63ef..eb0abeb0d 100644
--- a/docs/source/usersguide/scripts.rst
+++ b/docs/source/usersguide/scripts.rst
@@ -48,6 +48,7 @@ flags:
                        restart file
 -s, --threads N        Run with *N* OpenMP threads
 -t, --track            Write tracks for all particles (up to max_tracks)
+-q, --verbosity V      Set the output verbosity to *V*
 -v, --version          Show version information
 -h, --help             Show help message
 
diff --git a/man/man1/openmc.1 b/man/man1/openmc.1
index 7826a759a..30e8b2ce4 100644
--- a/man/man1/openmc.1
+++ b/man/man1/openmc.1
@@ -39,6 +39,9 @@ Use \fIN\fP OpenMP threads.
 .B "\-t\fR, \fP\-\-track"
 Write tracks for all particles (up to max_tracks).
 .TP
+.BI \-q " V" "\fR,\fP \-\-verbosity" " V"
+Set the output verbosity to \fIV\fP.
+.TP
 .B "\-v\fR, \fP\-\-version"
 Show version information.
 .TP
diff --git a/src/finalize.cpp b/src/finalize.cpp
index 9ee943409..344eaa1a0 100644
--- a/src/finalize.cpp
+++ b/src/finalize.cpp
@@ -142,7 +142,7 @@ int openmc_finalize()
   settings::uniform_source_sampling = false;
   settings::ufs_on = false;
   settings::urr_ptables_on = true;
-  settings::verbosity = 7;
+  settings::verbosity = -1;
   settings::weight_cutoff = 0.25;
   settings::weight_survive = 1.0;
   settings::weight_windows_file.clear();
diff --git a/src/initialize.cpp b/src/initialize.cpp
index e2a5b9743..a2269ed1e 100644
--- a/src/initialize.cpp
+++ b/src/initialize.cpp
@@ -226,6 +226,15 @@ int parse_command_line(int argc, char* argv[])
         i += 1;
         settings::n_particles = std::stoll(argv[i]);
 
+      } else if (arg == "-q" || arg == "--verbosity") {
+        i += 1;
+        settings::verbosity = std::stoi(argv[i]);
+        if (settings::verbosity > 10 || settings::verbosity < 1) {
+          auto msg = fmt::format("Invalid verbosity: {}.", settings::verbosity);
+          strcpy(openmc_err_msg, msg.c_str());
+          return OPENMC_E_INVALID_ARGUMENT;
+        }
+
       } else if (arg == "-e" || arg == "--event") {
         settings::event_based = true;
       } else if (arg == "-r" || arg == "--restart") {
@@ -376,8 +385,10 @@ bool read_model_xml()
   auto settings_root = root.child("settings");
 
   // Verbosity
-  if (check_for_node(settings_root, "verbosity")) {
+  if (check_for_node(settings_root, "verbosity") && settings::verbosity == -1) {
     settings::verbosity = std::stoi(get_node_value(settings_root, "verbosity"));
+  } else if (settings::verbosity == -1) {
+    settings::verbosity = 7;
   }
 
   // To this point, we haven't displayed any output since we didn't know what
diff --git a/src/output.cpp b/src/output.cpp
index 0a14e8843..80e2b10ab 100644
--- a/src/output.cpp
+++ b/src/output.cpp
@@ -281,6 +281,7 @@ void print_usage()
       "  -t, --track            Write tracks for all particles (up to "
       "max_tracks)\n"
       "  -e, --event            Run using event-based parallelism\n"
+      "  -q, --verbosity        Output verbosity\n"
       "  -v, --version          Show version information\n"
       "  -h, --help             Show this message\n");
   }
diff --git a/src/settings.cpp b/src/settings.cpp
index d47e9b5e6..5b472468f 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -145,7 +145,7 @@ int trace_gen;
 int64_t trace_particle;
 vector<array<int, 3>> track_identifiers;
 int trigger_batch_interval {1};
-int verbosity {7};
+int verbosity {-1};
 double weight_cutoff {0.25};
 double weight_survive {1.0};
 
@@ -396,8 +396,10 @@ void read_settings_xml()
   xml_node root = doc.document_element();
 
   // Verbosity
-  if (check_for_node(root, "verbosity")) {
+  if (check_for_node(root, "verbosity") && verbosity == -1) {
     verbosity = std::stoi(get_node_value(root, "verbosity"));
+  } else if (verbosity == -1) {
+    verbosity = 7;
   }
 
   // To this point, we haven't displayed any output since we didn't know what