diff --git a/.github/workflows/full_ci.yml b/.github/workflows/full_ci.yml
index 826d11d68d583..d8328a5b01a2c 100644
--- a/.github/workflows/full_ci.yml
+++ b/.github/workflows/full_ci.yml
@@ -6,6 +6,7 @@ on:
     types: [opened, synchronize, reopened]
 
 env:
+  CARGO_TERM_VERBOSE: 1
   LIBC_CI: 1
 
 jobs:
diff --git a/ci/android-install-ndk.sh b/ci/android-install-ndk.sh
index b57370d81e6f7..eb666e2db5da1 100644
--- a/ci/android-install-ndk.sh
+++ b/ci/android-install-ndk.sh
@@ -2,10 +2,10 @@
 
 set -ex
 
-NDK=android-ndk-r27
-wget --tries=20 -q https://dl.google.com/android/repository/${NDK}-linux.zip
-unzip -q ${NDK}-linux.zip
+ndk=android-ndk-r27
+wget --tries=20 -q "https://dl.google.com/android/repository/${ndk}-linux.zip"
+unzip -q "${ndk}-linux.zip"
 
-mv ./${NDK}/toolchains/llvm/prebuilt/linux-x86_64 /android
+mv "./${ndk}/toolchains/llvm/prebuilt/linux-x86_64" /android
 
-rm -rf ./${NDK}-linux.zip ./${NDK}
+rm -rf "./${ndk}-linux.zip" "./${ndk}"
diff --git a/ci/android-install-sdk.sh b/ci/android-install-sdk.sh
index 5e7037df044ef..c600824fbbb17 100644
--- a/ci/android-install-sdk.sh
+++ b/ci/android-install-sdk.sh
@@ -2,17 +2,17 @@
 
 set -ex
 
-# Prep the SDK and emulator
+# Prep the sdk and emulator
 #
 # Note that the update process requires that we accept a bunch of licenses, and
 # we can't just pipe `yes` into it for some reason, so we take the same strategy
 # located in https://github.com/appunite/docker by just wrapping it in a script
 # which apparently magically accepts the licenses.
 
-SDK=6609375
+sdk=6609375
 mkdir -p sdk/cmdline-tools
-wget -q --tries=20 https://dl.google.com/android/repository/commandlinetools-linux-${SDK}_latest.zip
-unzip -q -d sdk/cmdline-tools commandlinetools-linux-${SDK}_latest.zip
+wget -q --tries=20 "https://dl.google.com/android/repository/commandlinetools-linux-${sdk}_latest.zip"
+unzip -q -d sdk/cmdline-tools "commandlinetools-linux-${sdk}_latest.zip"
 
 case "$1" in
   arm | armv7)
@@ -69,4 +69,4 @@ echo "no" |
         --name "${1}" \
         --package "${image}" | grep -v = || true
 
-rm -rf commandlinetools-linux-${SDK}_latest.zip emulator-linux_x64-9058569.zip
+rm -rf "commandlinetools-linux-${sdk}_latest.zip" emulator-linux_x64-9058569.zip
diff --git a/ci/build.sh b/ci/build.sh
index d8e9dadbc14f2..947d4a21bcb65 100644
--- a/ci/build.sh
+++ b/ci/build.sh
@@ -10,29 +10,28 @@ set -ex
 : "${TOOLCHAIN?The TOOLCHAIN environment variable must be set.}"
 : "${OS?The OS environment variable must be set.}"
 
-RUST=${TOOLCHAIN}
-VERBOSE=-v
+rust="$TOOLCHAIN"
 
-echo "Testing Rust ${RUST} on ${OS}"
+echo "Testing Rust $rust on $OS"
 
-if [ "${TOOLCHAIN}" = "nightly" ] ; then
+if [ "$TOOLCHAIN" = "nightly" ] ; then
     rustup component add rust-src
 fi
 
 test_target() {
-    BUILD_CMD="${1}"
-    TARGET="${2}"
-    NO_STD="${3}"
+    build_cmd="${1}"
+    target="${2}"
+    no_std="${3}"
 
     # If there is a std component, fetch it:
-    if [ "${NO_STD}" != "1" ]; then
+    if [ "${no_std}" != "1" ]; then
         # FIXME: rustup often fails to download some artifacts due to network
         # issues, so we retry this N times.
         N=5
         n=0
         until [ $n -ge $N ]
         do
-            if rustup target add "${TARGET}" --toolchain "${RUST}" ; then
+            if rustup target add "$target" --toolchain "$rust" ; then
                 break
             fi
             n=$((n+1))
@@ -41,56 +40,75 @@ test_target() {
     fi
 
     # Test that libc builds without any default features (no std)
-    if [ "${NO_STD}" != "1" ]; then
-        cargo "+${RUST}" "${BUILD_CMD}" "$VERBOSE" --no-default-features --target "${TARGET}"
+    if [ "$no_std" != "1" ]; then
+        cargo "+$rust" "$build_cmd" --no-default-features --target "$target"
     else
         # FIXME: With `build-std` feature, `compiler_builtins` emits a lof of lint warnings.
-        RUSTFLAGS="-A improper_ctypes_definitions" cargo "+${RUST}" "${BUILD_CMD}" \
-            -Z build-std=core,alloc "$VERBOSE" --no-default-features --target "${TARGET}"
+        RUSTFLAGS="-A improper_ctypes_definitions" \
+            cargo "+$rust" "$build_cmd" \
+            -Z build-std=core,alloc \
+            --no-default-features \
+            --target "$target"
     fi
+
     # Test that libc builds with default features (e.g. std)
     # if the target supports std
-    if [ "$NO_STD" != "1" ]; then
-        cargo "+${RUST}" "${BUILD_CMD}" "$VERBOSE" --target "${TARGET}"
+    if [ "$no_std" != "1" ]; then
+        cargo "+$rust" "$build_cmd" --target "$target"
     else
-        RUSTFLAGS="-A improper_ctypes_definitions" cargo "+${RUST}" "${BUILD_CMD}" \
-            -Z build-std=core,alloc "$VERBOSE" --target "${TARGET}"
+        RUSTFLAGS="-A improper_ctypes_definitions" \
+            cargo "+$rust" "${build_cmd}" \
+            -Z build-std=core,alloc \
+            --target "$target"
     fi
 
     # Test that libc builds with the `extra_traits` feature
-    if [ "${NO_STD}" != "1" ]; then
-        cargo "+${RUST}" "${BUILD_CMD}" "$VERBOSE" --no-default-features --target "${TARGET}" \
-            --features extra_traits
+    if [ "$no_std" != "1" ]; then
+        cargo "+$rust" "$build_cmd" \
+            --no-default-features \
+            --features extra_traits \
+            --target "$target"
     else
-        RUSTFLAGS="-A improper_ctypes_definitions" cargo "+${RUST}" "${BUILD_CMD}" \
-            -Z build-std=core,alloc "$VERBOSE" --no-default-features \
-            --target "${TARGET}" --features extra_traits
+        RUSTFLAGS="-A improper_ctypes_definitions" \
+            cargo "+$rust" "$build_cmd" \
+            -Z build-std=core,alloc \
+            --no-default-features \
+            --features extra_traits \
+            --target "$target"
     fi
 
     # Test the 'const-extern-fn' feature on nightly
-    if [ "${RUST}" = "nightly" ]; then
-        if [ "${NO_STD}" != "1" ]; then
-            cargo "+${RUST}" "${BUILD_CMD}" "$VERBOSE" --no-default-features --target "${TARGET}" \
-                --features const-extern-fn
+    if [ "${rust}" = "nightly" ]; then
+        if [ "${no_std}" != "1" ]; then
+            cargo "+$rust" "$build_cmd" \
+                --no-default-features \
+                --features const-extern-fn \
+                --target "$target"
         else
-            RUSTFLAGS="-A improper_ctypes_definitions" cargo "+${RUST}" "${BUILD_CMD}" \
-                -Z build-std=core,alloc "$VERBOSE" --no-default-features \
-                --target "${TARGET}" --features const-extern-fn
+            RUSTFLAGS="-A improper_ctypes_definitions" \
+                cargo "+$rust" "$build_cmd" \
+                -Z build-std=core,alloc \
+                --no-default-features \
+                --features const-extern-fn \
+                --target "$target"
         fi
     fi
 
     # Also test that it builds with `extra_traits` and default features:
-    if [ "$NO_STD" != "1" ]; then
-        cargo "+${RUST}" "${BUILD_CMD}" "$VERBOSE" --target "${TARGET}" \
+    if [ "$no_std" != "1" ]; then
+        cargo "+$rust" "$build_cmd" \
+            --target "$target" \
             --features extra_traits
     else
-        RUSTFLAGS="-A improper_ctypes_definitions" cargo "+${RUST}" "${BUILD_CMD}" \
-            -Z build-std=core,alloc "$VERBOSE" --target "${TARGET}" \
+        RUSTFLAGS="-A improper_ctypes_definitions" \
+            cargo "+$rust" "$build_cmd" \
+            -Z build-std=core,alloc \
+            --target "$target" \
             --features extra_traits
     fi
 }
 
-RUST_LINUX_TARGETS="\
+rust_linux_targets="\
 aarch64-linux-android \
 aarch64-unknown-linux-gnu \
 arm-linux-androideabi \
@@ -113,7 +131,7 @@ x86_64-unknown-linux-musl \
 x86_64-unknown-netbsd \
 "
 
-RUST_GT_1_13_LINUX_TARGETS="\
+rust_gt_1_13_linux_targets="\
 arm-unknown-linux-musleabi \
 arm-unknown-linux-musleabihf \
 armv7-unknown-linux-musleabihf \
@@ -121,16 +139,16 @@ sparc64-unknown-linux-gnu \
 wasm32-unknown-emscripten \
 x86_64-linux-android \
 "
-RUST_GT_1_19_LINUX_TARGETS="\
+rust_gt_1_19_linux_targets="\
 aarch64-unknown-linux-musl \
 sparcv9-sun-solaris \
 wasm32-unknown-unknown \
 "
-RUST_GT_1_24_LINUX_TARGETS="\
+rust_gt_1_24_linux_targets="\
 i586-unknown-linux-musl \
 "
 
-RUST_NIGHTLY_LINUX_TARGETS="\
+rust_nightly_linux_targets="\
 aarch64-unknown-fuchsia \
 armv5te-unknown-linux-gnueabi \
 armv5te-unknown-linux-musleabi \
@@ -145,65 +163,63 @@ x86_64-unknown-linux-gnux32 \
 x86_64-unknown-redox \
 "
 
-RUST_APPLE_TARGETS="\
+rust_apple_targets="\
 aarch64-apple-ios \
 "
 
-RUST_NIGHTLY_APPLE_TARGETS="\
+rust_nightly_apple_targets="\
 aarch64-apple-darwin \
 "
 
 # Must start with `x86_64-pc-windows-msvc` first.
-RUST_NIGHTLY_WINDOWS_TARGETS="\
+rust_nightly_windows_targets="\
 x86_64-pc-windows-msvc \
 x86_64-pc-windows-gnu \
 i686-pc-windows-msvc \
 "
 
 # The targets are listed here alphabetically
-TARGETS=""
+targets=""
 case "${OS}" in
     linux*)
-        TARGETS="${RUST_LINUX_TARGETS}"
+        targets="$rust_linux_targets"
 
-        if [ "${RUST}" != "1.13.0" ]; then
-            TARGETS="${TARGETS} ${RUST_GT_1_13_LINUX_TARGETS}"
-            if [ "${RUST}" != "1.19.0" ]; then
-                TARGETS="${TARGETS} ${RUST_GT_1_19_LINUX_TARGETS}"
-                if [ "${RUST}" != "1.24.0" ]; then
-                    TARGETS="${TARGETS} ${RUST_GT_1_24_LINUX_TARGETS}"
+        if [ "$rust" != "1.13.0" ]; then
+            targets="$targets $rust_gt_1_13_linux_targets"
+            if [ "$rust" != "1.19.0" ]; then
+                targets="$targets $rust_gt_1_19_linux_targets"
+                if [ "${rust}" != "1.24.0" ]; then
+                    targets="$targets $rust_gt_1_24_linux_targets"
                 fi
             fi
         fi
 
-        if [ "${RUST}" = "nightly" ]; then
-            TARGETS="${TARGETS} ${RUST_NIGHTLY_LINUX_TARGETS}"
+        if [ "$rust" = "nightly" ]; then
+            targets="$targets $rust_nightly_linux_targets"
         fi
 
         ;;
     macos*)
-        TARGETS="${RUST_APPLE_TARGETS}"
+        targets="$rust_apple_targets"
 
-        if [ "${RUST}" = "nightly" ]; then
-            TARGETS="${TARGETS} ${RUST_NIGHTLY_APPLE_TARGETS}"
+        if [ "$rust" = "nightly" ]; then
+            targets="$targets $rust_nightly_apple_targets"
         fi
 
         ;;
     windows*)
-        TARGETS=${RUST_NIGHTLY_WINDOWS_TARGETS}
-
-        ;;
-    *)
+        targets=${rust_nightly_windows_targets}
         ;;
+    *) ;;
 esac
 
-for TARGET in $TARGETS; do
-    if echo "$TARGET"|grep -q "$FILTER"; then
+for target in $targets; do
+    if echo "$target" | grep -q "$FILTER"; then
         if [ "${OS}" = "windows" ]; then
-            TARGET="$TARGET" sh ./ci/install-rust.sh
-            test_target build "$TARGET"
+            target="$target" sh ./ci/install-rust.sh
+            test_target build "$target"
         else
-            test_target build "$TARGET"
+            test_target build "$target"
         fi
     fi
 done
@@ -211,7 +227,7 @@ done
 # Targets which are not available via rustup and must be built with -Zbuild-std
 # FIXME(hexagon): hexagon-unknown-linux-musl should be tested but currently has
 # duplicate symbol errors from `compiler_builtins`.
-RUST_LINUX_NO_CORE_TARGETS="\
+rust_linux_no_core_targets="\
 aarch64-pc-windows-msvc \
 aarch64-unknown-freebsd \
 aarch64-unknown-hermit \
@@ -275,24 +291,24 @@ x86_64-unknown-openbsd \
 x86_64-wrs-vxworks \
 "
 
-if [ "${RUST}" = "nightly" ] && [ "${OS}" = "linux" ]; then
-    for TARGET in $RUST_LINUX_NO_CORE_TARGETS; do
-        if echo "$TARGET"|grep -q "$FILTER"; then
-            test_target build "$TARGET" 1
+if [ "${rust}" = "nightly" ] && [ "${OS}" = "linux" ]; then
+    for target in $rust_linux_no_core_targets; do
+        if echo "$target" | grep -q "$FILTER"; then
+            test_target build "$target" 1
         fi
     done
 fi
 
-RUST_APPLE_NO_CORE_TARGETS="\
+rust_apple_no_core_targets="\
 armv7s-apple-ios \
 i686-apple-darwin \
 i386-apple-ios \
 "
 
-if [ "${RUST}" = "nightly" ] && [ "${OS}" = "macos" ]; then
-    for TARGET in $RUST_APPLE_NO_CORE_TARGETS; do
-        if echo "$TARGET" | grep -q "$FILTER"; then
-            test_target build "$TARGET" 1
+if [ "${rust}" = "nightly" ] && [ "${OS}" = "macos" ]; then
+    for target in $rust_apple_no_core_targets; do
+        if echo "$target" | grep -q "$FILTER"; then
+            test_target build "$target" 1
         fi
     done
 fi
diff --git a/ci/docker/wasm32-unknown-emscripten/node-wrapper.sh b/ci/docker/wasm32-unknown-emscripten/node-wrapper.sh
index b1936f041070a..369439269a683 100755
--- a/ci/docker/wasm32-unknown-emscripten/node-wrapper.sh
+++ b/ci/docker/wasm32-unknown-emscripten/node-wrapper.sh
@@ -2,10 +2,10 @@
 
 set -e
 
-me=$1
+me="$1"
 shift
-dir=$(dirname $me)
-file=$(basename $me)
+dir=$(dirname "$me")
+file=$(basename "$me")
 
-cd $dir
-exec node $file "$@"
+cd "$dir"
+exec node "$file" "$@"
diff --git a/ci/emscripten.sh b/ci/emscripten.sh
index b99d2cfbe5397..b17a40c1a287d 100644
--- a/ci/emscripten.sh
+++ b/ci/emscripten.sh
@@ -4,12 +4,12 @@ set -ex
 
 # Note: keep in sync with:
 # https://github.com/rust-lang/rust/blob/master/src/ci/docker/scripts/emscripten.sh
-EMSDK_VERSION=3.1.68
+emsdk_version=3.1.68
 
 git clone https://github.com/emscripten-core/emsdk.git /emsdk-portable
 cd /emsdk-portable
-./emsdk install "${EMSDK_VERSION}"
-./emsdk activate "${EMSDK_VERSION}"
+./emsdk install "$emsdk_version"
+./emsdk activate "$emsdk_version"
 
 # Compile and cache libc
 # shellcheck disable=SC1091
diff --git a/ci/install-musl.sh b/ci/install-musl.sh
index 7ea50916c4caf..2375d7426df38 100644
--- a/ci/install-musl.sh
+++ b/ci/install-musl.sh
@@ -1,17 +1,17 @@
-#!/usr/bin/env sh
+#!/bin/sh
 #
 # Install musl and musl-sanitized linux kernel headers
 # to musl-{$1} directory
 
 set -ex
 
-MUSL_VERSION=1.1.24
-MUSL="musl-${MUSL_VERSION}"
+musl_version=1.1.24
+musl="musl-${musl_version}"
 
 # Download, configure, build, and install musl:
-curl --retry 5 https://www.musl-libc.org/releases/${MUSL}.tar.gz | tar xzf -
+curl --retry 5 https://www.musl-libc.org/releases/${musl}.tar.gz | tar xzf -
 
-cd $MUSL
+cd "$musl"
 case ${1} in
     aarch64)
         musl_arch=aarch64
@@ -62,15 +62,15 @@ esac
 
 # shellcheck disable=SC2103
 cd ..
-rm -rf $MUSL
+rm -rf "$musl"
 
 # Download, configure, build, and install musl-sanitized kernel headers:
-KERNEL_HEADER_VER="4.19.88"
+kernel_header_ver="4.19.88"
 curl --retry 5 -L \
-     "https://github.com/sabotage-linux/kernel-headers/archive/v${KERNEL_HEADER_VER}.tar.gz" | \
+     "https://github.com/sabotage-linux/kernel-headers/archive/v${kernel_header_ver}.tar.gz" | \
     tar xzf -
 (
-    cd kernel-headers-${KERNEL_HEADER_VER}
+    cd "kernel-headers-${kernel_header_ver}"
     make ARCH="${kernel_arch}" prefix="/musl-${musl_arch}" install -j4
 )
-rm -rf kernel-headers-${KERNEL_HEADER_VER}
+rm -rf kernel-headers-${kernel_header_ver}
diff --git a/ci/run-docker.sh b/ci/run-docker.sh
index 042303846f3fe..a812ee7ab183a 100755
--- a/ci/run-docker.sh
+++ b/ci/run-docker.sh
@@ -1,4 +1,4 @@
-#!/usr/bin/env sh
+#!/bin/sh
 
 # Disable SC2086 as it confuses the docker command.
 # shellcheck disable=SC2086
@@ -10,18 +10,18 @@ set -ex
 
 # Default to assuming the CARGO_HOME is one directory up (to account for a `bin`
 # subdir) from where the `cargo` binary in `$PATH` lives.
-DEFAULT_CARGO_HOME="$(dirname "$(dirname "$(command -v cargo)")")"
+default_cargo_home="$(dirname "$(dirname "$(command -v cargo)")")"
 # If the CARGO_HOME env var is already set, use that. If it isn't set use the
 # default.
-CARGO_HOME="${CARGO_HOME:-$DEFAULT_CARGO_HOME}"
+export CARGO_HOME="${CARGO_HOME:-$default_cargo_home}"
 
 echo "${HOME}"
 pwd
 
 # Avoid "no space left on device" failure.
 if [ "${1}" = "aarch64-linux-android" ] ; then
-  docker system prune -af
-  docker system df
+    docker system prune -af
+    docker system df
 fi
 
 run() {
@@ -37,21 +37,21 @@ run() {
     fi
 
     docker run \
-      --rm \
-      --user "$(id -u)":"$(id -g)" \
-      --env LIBC_CI \
-      --env LIBC_CI_ZBUILD_STD \
-      --env CARGO_HOME=/cargo \
-      --env CARGO_TARGET_DIR=/checkout/target \
-      --volume "$CARGO_HOME":/cargo \
-      --volume "$(rustc --print sysroot)":/rust:ro \
-      --volume "$(pwd)":/checkout:ro \
-      --volume "$(pwd)"/target:/checkout/target \
-      $kvm \
-      --init \
-      --workdir /checkout \
-      "libc-${1}" \
-      sh -c "HOME=/tmp PATH=\$PATH:/rust/bin exec ci/run.sh ${1}"
+        --rm \
+        --user "$(id -u)":"$(id -g)" \
+        --env LIBC_CI \
+        --env LIBC_CI_ZBUILD_STD \
+        --env CARGO_HOME=/cargo \
+        --env CARGO_TARGET_DIR=/checkout/target \
+        --volume "$CARGO_HOME":/cargo \
+        --volume "$(rustc --print sysroot)":/rust:ro \
+        --volume "$(pwd)":/checkout:ro \
+        --volume "$(pwd)"/target:/checkout/target \
+        $kvm \
+        --init \
+        --workdir /checkout \
+        "libc-${1}" \
+        sh -c "HOME=/tmp PATH=\$PATH:/rust/bin exec ci/run.sh ${1}"
 }
 
 build_switch() {
@@ -69,23 +69,23 @@ build_switch() {
     cp "$(command -v rustup)" "$(rustc --print sysroot)/bin"
 
     docker run \
-      --rm \
-      --user "$(id -u)":"$(id -g)" \
-      --env LIBC_CI \
-      --env CARGO_HOME=/cargo \
-      --env CARGO_TARGET_DIR=/checkout/target \
-      --volume "$CARGO_HOME":/cargo \
-      --volume "$(rustc --print sysroot)":/rust:ro \
-      --volume "$(pwd)":/checkout:ro \
-      --volume "$(pwd)"/target:/checkout/target \
-      --volume ~/.rustup:/.rustup:Z \
-      $kvm \
-      --init \
-      --workdir /checkout \
-      libc-switch \
-      sh -c "HOME=/tmp RUSTUP_HOME=/tmp PATH=\$PATH:/rust/bin rustup default nightly \
-        && rustup component add rust-src --target ci/switch.json \
-        && cargo build -Z build-std=core,alloc --target ci/switch.json"
+        --rm \
+        --user "$(id -u)":"$(id -g)" \
+        --env LIBC_CI \
+        --env CARGO_HOME=/cargo \
+        --env CARGO_TARGET_DIR=/checkout/target \
+        --volume "$CARGO_HOME":/cargo \
+        --volume "$(rustc --print sysroot)":/rust:ro \
+        --volume "$(pwd)":/checkout:ro \
+        --volume "$(pwd)"/target:/checkout/target \
+        --volume ~/.rustup:/.rustup:Z \
+        $kvm \
+        --init \
+        --workdir /checkout \
+        libc-switch \
+        sh -c "HOME=/tmp RUSTUP_HOME=/tmp PATH=\$PATH:/rust/bin rustup default nightly \
+            && rustup component add rust-src --target ci/switch.json \
+            && cargo build -Z build-std=core,alloc --target ci/switch.json"
 }
 
 if [ -z "${1}" ]; then
diff --git a/ci/run.sh b/ci/run.sh
index 4de8087699e24..f973631caa979 100755
--- a/ci/run.sh
+++ b/ci/run.sh
@@ -5,9 +5,9 @@
 
 set -ex
 
-MIRRORS_URL="https://ci-mirrors.rust-lang.org/libc"
+mirrors_url="https://ci-mirrors.rust-lang.org/libc"
 
-TARGET="${1}"
+target="$1"
 
 # If we're going to run tests inside of a qemu image, then we don't need any of
 # the scripts below. Instead, download the image, prepare a filesystem which has
@@ -23,21 +23,21 @@ if [ "$QEMU" != "" ]; then
     # image is .gz : download and uncompress it
     qemufile="$(echo "${QEMU%.gz}" | sed 's/\//__/g')"
     if [ ! -f "${tmpdir}/${qemufile}" ]; then
-      curl --retry 5 "${MIRRORS_URL}/${QEMU}" | \
+      curl --retry 5 "${mirrors_url}/${QEMU}" | \
           gunzip -d > "${tmpdir}/${qemufile}"
     fi
   elif [ -z "${QEMU#*.xz}" ]; then
     # image is .xz : download and uncompress it
     qemufile="$(echo "${QEMU%.xz}" | sed 's/\//__/g')"
     if [ ! -f "${tmpdir}/${qemufile}" ]; then
-      curl --retry 5 "${MIRRORS_URL}/${QEMU}" | \
+      curl --retry 5 "${mirrors_url}/${QEMU}" | \
           unxz > "${tmpdir}/${qemufile}"
     fi
   else
     # plain qcow2 image: just download it
     qemufile="$(echo "${QEMU}" | sed 's/\//__/g')"
     if [ ! -f "${tmpdir}/${qemufile}" ]; then
-      curl --retry 5 "${MIRRORS_URL}/${QEMU}" \
+      curl --retry 5 "${mirrors_url}/${QEMU}" \
         > "${tmpdir}/${qemufile}"
     fi
   fi
@@ -52,10 +52,10 @@ if [ "$QEMU" != "" ]; then
   # script to run just executes the binary.
   cargo build \
     --manifest-path libc-test/Cargo.toml \
-    --target "${TARGET}" \
+    --target "$target" \
     --test main ${LIBC_CI_ZBUILD_STD+"-Zbuild-std"}
-  rm "${CARGO_TARGET_DIR}/${TARGET}"/debug/main-*.d
-  cp "${CARGO_TARGET_DIR}/${TARGET}"/debug/main-* "${tmpdir}"/mount/libc-test
+  rm "${CARGO_TARGET_DIR}/${target}"/debug/main-*.d
+  cp "${CARGO_TARGET_DIR}/${target}"/debug/main-* "${tmpdir}"/mount/libc-test
   # shellcheck disable=SC2016
   echo 'exec $1/libc-test' > "${tmpdir}/mount/run.sh"
 
@@ -82,7 +82,7 @@ if [ "$QEMU" != "" ]; then
   exec grep -E "^(PASSED)|(test result: ok)" "${CARGO_TARGET_DIR}/out.log"
 fi
 
-if [ "$TARGET" = "s390x-unknown-linux-gnu" ]; then
+if [ "$target" = "s390x-unknown-linux-gnu" ]; then
   # FIXME: s390x-unknown-linux-gnu often fails to test due to timeout,
   # so we retry this N times.
   N=5
@@ -91,17 +91,17 @@ if [ "$TARGET" = "s390x-unknown-linux-gnu" ]; then
   until [ $n -ge $N ]
   do
     if [ "$passed" = "0" ]; then
-      if cargo test --no-default-features --manifest-path libc-test/Cargo.toml --target "${TARGET}" ${LIBC_CI_ZBUILD_STD+"-Zbuild-std"} ; then
+      if cargo test --no-default-features --manifest-path libc-test/Cargo.toml --target "$target" ${LIBC_CI_ZBUILD_STD+"-Zbuild-std"} ; then
         passed=$((passed+1))
         continue
       fi
     elif [ "$passed" = "1" ]; then
-      if cargo test --manifest-path libc-test/Cargo.toml --target "${TARGET}" ${LIBC_CI_ZBUILD_STD+"-Zbuild-std"} ; then
+      if cargo test --manifest-path libc-test/Cargo.toml --target "$target" ${LIBC_CI_ZBUILD_STD+"-Zbuild-std"} ; then
         passed=$((passed+1))
         continue
       fi
     elif [ "$passed" = "2" ]; then
-      if cargo test --features extra_traits --manifest-path libc-test/Cargo.toml --target "${TARGET}" ${LIBC_CI_ZBUILD_STD+"-Zbuild-std"}; then
+      if cargo test --features extra_traits --manifest-path libc-test/Cargo.toml --target "$target" ${LIBC_CI_ZBUILD_STD+"-Zbuild-std"}; then
         break
       fi
     fi
@@ -110,10 +110,10 @@ if [ "$TARGET" = "s390x-unknown-linux-gnu" ]; then
   done
 else
   cargo test --no-default-features --manifest-path libc-test/Cargo.toml \
-    --target "${TARGET}" ${LIBC_CI_ZBUILD_STD+"-Zbuild-std"}
+    --target "$target" ${LIBC_CI_ZBUILD_STD+"-Zbuild-std"}
 
-  cargo test --manifest-path libc-test/Cargo.toml --target "${TARGET}" ${LIBC_CI_ZBUILD_STD+"-Zbuild-std"}
+  cargo test --manifest-path libc-test/Cargo.toml --target "$target" ${LIBC_CI_ZBUILD_STD+"-Zbuild-std"}
 
   RUST_BACKTRACE=1 cargo test --features extra_traits --manifest-path libc-test/Cargo.toml \
-    --target "${TARGET}" ${LIBC_CI_ZBUILD_STD+"-Zbuild-std"}
+    --target "$target" ${LIBC_CI_ZBUILD_STD+"-Zbuild-std"}
 fi
diff --git a/ci/style.sh b/ci/style.sh
index c8d49e163de96..59f8452552b73 100755
--- a/ci/style.sh
+++ b/ci/style.sh
@@ -11,8 +11,7 @@ rustfmt -V
 cargo fmt --all -- --check
 
 if shellcheck --version ; then
-    # GHA's shellcheck is too old (0.4.6) and cannot handle SC2153 correctly.
-    shellcheck -e SC2103 -e SC2153 ci/*.sh
+    shellcheck ci/*.sh
 else
     echo "shellcheck not found"
     exit 1