Add a script to test SD cards

.editorconfig

@@ -0,0 +1,7 @@
+[*.sh]
+indent_style = space
+indent_size = 4
+
+[.envrc]
+indent_style = space
+indent_size = 4

scripts/test_sd_card.sh

@@ -0,0 +1,55 @@
+#!/usr/bin/env nix-shell
+#! nix-shell -i bash --pure
+#! nix-shell -p bash coreutils gawk hdparm iozone
+#! nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/d588537b901fe0020ab4405dd5829713da329b7c.tar.gz
+
+# Raspberry Pi microSD card benchmark script.
+#
+# A script I use to automate the running and reporting of benchmarks I compile
+# for: http://www.pidramble.com/wiki/benchmarks/microsd-cards
+#
+# Usage:
+#   # Run it locally.
+#   $ sudo ./microsd-benchmarks.sh
+#
+#   # Run it straight from GitHub.
+#   $ curl https://raw.githubusercontent.com/geerlingguy/raspberry-pi-dramble/master/setup/benchmarks/microsd-benchmarks.sh | sudo bash
+#
+# Another good benchmark:
+#   $ curl http://www.nmacleod.com/public/sdbench.sh | sudo bash
+#
+# Author: Jeff Geerling, 2016 (last updated 2020)
+
+printf "\n"
+printf "Raspberry Pi Dramble microSD benchmarks\n"
+
+CLOCK="$(grep "actual clock" /sys/kernel/debug/mmc0/ios 2>/dev/null | awk '{printf("%0.3f MHz", $3/1000000)}')"
+if [ -n "$CLOCK" ]; then
+    echo "microSD clock: $CLOCK"
+fi
+printf "\n"
+
+# Fail if $SUDO_USER is empty.
+if [ -z "$SUDO_USER" ]; then
+    printf "This script must be run with sudo.\n"
+    exit 1
+fi
+
+# Variables.
+USER_HOME_PATH=$(getent passwd $SUDO_USER | cut -d: -f6)
+
+# Run benchmarks.
+printf "Running hdparm test...\n"
+sudo hdparm -t /dev/mmcblk0
+printf "\n"
+
+printf "Running dd test...\n\n"
+dd if=/dev/zero of=${USER_HOME_PATH}/test bs=8k count=50k conv=fsync
+sudo rm -f ${USER_HOME_PATH}/test
+printf "\n"
+
+printf "Running iozone test...\n"
+sudo ./iozone -e -I -a -s 100M -r 4k -i 0 -i 1 -i 2
+printf "\n"
+
+printf "microSD card benchmark complete!\n\n"