diff --git a/ci/.shellcheckrc b/ci/.shellcheckrc
index 3ee2a1e6e..0260dcca3 100644
--- a/ci/.shellcheckrc
+++ b/ci/.shellcheckrc
@@ -1,3 +1,7 @@
+# Disable the "variable appears unused" warning caused by the use of getopts
+# with an obligatory (but unused) variable name in the main function.
+disable=SC2034
+
 # Disable all the "quote to prevent globbing or word splitting" advice.
 # We need word splitting for well-known variables like MAKEFLAGS and CFLAGS.
 disable=SC2086,SC2206
diff --git a/ci/ci_lint_ci.sh b/ci/ci_lint_ci.sh
index fa45c5473..13a9d21d6 100755
--- a/ci/ci_lint_ci.sh
+++ b/ci/ci_lint_ci.sh
@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 set -e
 
-# Copyright (c) 2019-2023 Cosmin Truta.
+# Copyright (c) 2019-2024 Cosmin Truta.
 #
 # Use, modification and distribution are subject
 # to the Boost Software License, Version 1.0.
@@ -58,11 +58,22 @@ function ci_lint_ci_scripts_license {
     }
 }
 
+function usage {
+    echo "usage: $CI_SCRIPT_NAME"
+    exit 0
+}
+
 function main {
-    [[ $# -eq 0 ]] || {
-        ci_info "usage: $CI_SCRIPT_NAME"
-        ci_err "unexpected command argument: '$1'"
-    }
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help ]] && usage
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    # And... go!
+    [[ $# -eq 0 ]] || ci_err "unexpected argument: '$1'"
     ci_lint_ci_config_files
     ci_lint_ci_scripts
     ci_lint_ci_scripts_license
diff --git a/ci/ci_verify_cmake.sh b/ci/ci_verify_cmake.sh
index b46e9c6bf..06c46a0ba 100755
--- a/ci/ci_verify_cmake.sh
+++ b/ci/ci_verify_cmake.sh
@@ -169,12 +169,25 @@ function ci_build {
     ci_info "## END OF BUILD ##"
 }
 
+function usage {
+    echo "usage: $CI_SCRIPT_NAME"
+    exit 0
+}
+
 function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help ]] && usage
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
     ci_init_build
     ci_trace_build
     [[ $# -eq 0 ]] || {
-        ci_info "note: this program accepts environment options only (see above)"
-        ci_err "unexpected command argument: '$1'"
+        ci_info "note: this program accepts environment options only"
+        ci_err "unexpected argument: '$1'"
     }
     ci_cleanup_old_build
     ci_build
diff --git a/ci/ci_verify_configure.sh b/ci/ci_verify_configure.sh
index fa7e82e65..94abda794 100755
--- a/ci/ci_verify_configure.sh
+++ b/ci/ci_verify_configure.sh
@@ -122,12 +122,26 @@ function ci_build {
     ci_info "## END OF BUILD ##"
 }
 
+function usage {
+    echo "usage: $CI_SCRIPT_NAME"
+    exit 0
+}
+
 function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help ]] && usage
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    # And... go!
     ci_init_build
     ci_trace_build
     [[ $# -eq 0 ]] || {
-        ci_info "note: this program accepts environment options only (see above)"
-        ci_err "unexpected command argument: '$1'"
+        ci_info "note: this program accepts environment options only"
+        ci_err "unexpected argument: '$1'"
     }
     ci_cleanup_old_build
     ci_build
diff --git a/ci/ci_verify_makefiles.sh b/ci/ci_verify_makefiles.sh
index 79b97a383..95a64bb21 100755
--- a/ci/ci_verify_makefiles.sh
+++ b/ci/ci_verify_makefiles.sh
@@ -137,12 +137,26 @@ function ci_build {
     ci_info "## END OF BUILD ##"
 }
 
+function usage {
+    echo "usage: $CI_SCRIPT_NAME"
+    exit 0
+}
+
 function main {
+    local opt
+    while getopts ":" opt
+    do
+        # This ain't a while-loop. It only pretends to be.
+        [[ $1 == -[?h]* || $1 == --help ]] && usage
+        ci_err "unknown option: '$1'"
+    done
+    shift $((OPTIND - 1))
+    # And... go!
     ci_init_build
     ci_trace_build
     [[ $# -eq 0 ]] || {
-        ci_info "note: this program accepts environment options only (see above)"
-        ci_err "unexpected command argument: '$1'"
+        ci_info "note: this program accepts environment options only"
+        ci_err "unexpected argument: '$1'"
     }
     ci_cleanup_old_build
     ci_build
diff --git a/ci/lib/ci.lib.sh b/ci/lib/ci.lib.sh
index fc3e1b653..8700f3161 100644
--- a/ci/lib/ci.lib.sh
+++ b/ci/lib/ci.lib.sh
@@ -1,4 +1,4 @@
-# Copyright (c) 2019-2023 Cosmin Truta.
+# Copyright (c) 2019-2024 Cosmin Truta.
 #
 # Use, modification and distribution are subject
 # to the Boost Software License, Version 1.0.
@@ -73,7 +73,7 @@ function ci_spawn {
     "$@"
 }
 
-# Ensure that the initialization is correct.
+# Ensure that the internal initialization is correct.
 [[ $CI_TOPLEVEL_DIR/ci/lib/ci.lib.sh -ef ${BASH_SOURCE[0]} ]] ||
     ci_err_internal "bad or missing \$CI_TOPLEVEL_DIR"
 [[ $CI_SCRIPT_DIR/$CI_SCRIPT_NAME -ef $0 ]] ||
@@ -82,3 +82,11 @@ function ci_spawn {
     ci_err_internal "missing \$CI_BUILD_ARCH or \$CI_BUILD_SYSTEM"
 [[ $CI_TARGET_ARCH && $CI_TARGET_SYSTEM ]] ||
     ci_err_internal "missing \$CI_TARGET_ARCH or \$CI_TARGET_SYSTEM"
+
+# Ensure that the user initialization is correct.
+[[ ${CI_NO_TEST:-0} == [01] ]] ||
+    ci_err "bad boolean option: \$CI_NO_TEST: '$CI_NO_TEST'"
+[[ ${CI_NO_INSTALL:-0} == [01] ]] ||
+    ci_err "bad boolean option: \$CI_NO_INSTALL: '$CI_NO_INSTALL'"
+[[ ${CI_NO_CLEAN:-0} == [01] ]] ||
+    ci_err "bad boolean option: \$CI_NO_CLEAN: '$CI_NO_CLEAN'"