diff --git a/build-cran-package.sh b/build-cran-package.sh
index 04f207523aa6..06074e549966 100755
--- a/build-cran-package.sh
+++ b/build-cran-package.sh
@@ -63,7 +63,7 @@ CURRENT_DATE=$(date +'%Y-%m-%d')
 
 # R packages cannot have versions like 3.0.0rc1, but
 # 3.0.0-1 is acceptable
-LGB_VERSION=$(sed "s/rc/-/g" < VERSION.txt)
+LGB_VERSION=$(head -1 ./VERSION.txt | sed "s/rc/-/g")
 
 # move relevant files
 cp -R R-package/* "${TEMP_R_DIR}"
@@ -153,7 +153,6 @@ cd "${TEMP_R_DIR}"
         -e 's/^.*#pragma endregion.*$//' \
         -e 's/^.*#pragma warning.*$//' \
         {} +
-    find . -name '*.bak' -exec rm {} \;
 
     # 'processx' is listed as a 'Suggests' dependency in DESCRIPTION
     # because it is used in install.libs.R, a file that is not
@@ -164,7 +163,7 @@ cd "${TEMP_R_DIR}"
         DESCRIPTION
 
     echo "Cleaning sed backup files"
-    rm ./*.bak
+    find . -name '*.bak' -exec rm {} \;
 
 cd "${ORIG_WD}"
 
diff --git a/build-python.sh b/build-python.sh
index 68d1fc15095e..cf790737729e 100755
--- a/build-python.sh
+++ b/build-python.sh
@@ -340,20 +340,22 @@ fi
 if test "${BUILD_SDIST}" = true; then
     echo "--- building sdist ---"
     rm -f ../dist/*.tar.gz
+    # shellcheck disable=SC2086
     python -m build \
         --sdist \
         --outdir ../dist \
-        ${BUILD_ARGS:+${BUILD_ARGS}} \
+        ${BUILD_ARGS} \
         .
 fi
 
 if test "${BUILD_WHEEL}" = true; then
     echo "--- building wheel ---"
     rm -f ../dist/*.whl || true
+    # shellcheck disable=SC2086
     python -m build \
         --wheel \
         --outdir ../dist \
-        ${BUILD_ARGS:+${BUILD_ARGS}} \
+        ${BUILD_ARGS} \
         .
 fi
 
@@ -366,8 +368,9 @@ if test "${INSTALL}" = true; then
         PACKAGE_NAME="$(echo lightgbm*.tar.gz)"
     fi
     # ref for use of '--find-links': https://stackoverflow.com/a/52481267/3986677
+    # shellcheck disable=SC2086
     pip install \
-        ${PIP_INSTALL_ARGS:+ -o "$PIP_INSTALL_ARGS"} \
+        ${PIP_INSTALL_ARGS} \
         --force-reinstall \
         --no-cache-dir \
         --no-deps \