A set of tools that might be useful later (#7180)

tools/bootstrap/python

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+#!/bin/sh
+# bootstrap/python
+#
+# Python-finding script for all `sh` environments, including Linux, MSYS2,
+# Git for Windows, and GitHub Desktop. Invokable from CLI or automation.
+#
+# If a python.exe installed by `python_.ps1` is present, it will be used.
+# Otherwise, this script requires a system `python3` and `pip` to be provided,
+# and will create a standard virtualenv in which to install `requirements.txt`.
+set -e
+
+# Convenience variables
+Bootstrap="$(dirname "$0")"
+Sdk="$(dirname "$Bootstrap")"
+Cache="$Bootstrap/.cache"
+if [ "$TG_BOOTSTRAP_CACHE" ]; then
+	Cache="$TG_BOOTSTRAP_CACHE"
+fi
+OldPWD="$PWD"
+cd "$Bootstrap/../.."
+. ./_build_dependencies.sh  # sets PYTHON_VERSION
+cd "$OldPWD"
+PythonVersion="$PYTHON_VERSION"
+PythonDir="$Cache/python-$PythonVersion"
+PythonExe="$PythonDir/python.exe"
+Log="$Cache/last-command.log"
+
+# If a portable Python for Windows is not present, search on $PATH.
+if [ "$(uname)" = "Linux" ] || [ ! -f "$PythonExe" ]; then
+	# Strip the "App Execution Aliases" from $PATH. Even if the user installed
+	# Python using the Windows Store on purpose, these aliases always generate
+	# "Permission denied" errors when sh.exe tries to invoke them.
+	PATH=$(echo "$PATH" | tr ":" "\n" | grep -v "AppData/Local/Microsoft/WindowsApps" | tr "\n" ":")
+
+	# Try to find a Python executable.
+	if command -v python3 >/dev/null 2>&1; then
+		PythonExe=python3
+	elif command -v python >/dev/null 2>&1; then
+		PythonExe=python
+	elif command -v py >/dev/null 2>&1; then
+		PythonExe="py -3"
+	else
+		echo
+		if command -v apt-get >/dev/null 2>&1; then
+			echo "Please install Python using your system's package manager:"
+			echo "    sudo apt-get install python3 python3-pip"
+		elif [ "$(uname -o)" = "Msys" ]; then
+			echo "Please run tools/bootstrap/python.bat instead of tools/bootstrap/python once to"
+			echo "install Python automatically, or install it from https://www.python.org/downloads/"
+			# TODO: give MSYS pacman advice?
+		elif command -v pacman >/dev/null 2>&1; then
+			echo "Please install Python using your system's package manager:"
+			echo "    sudo pacman -S python python-pip"
+		else
+			echo "Please install Python from https://www.python.org/downloads/ or using your system's package manager."
+		fi
+		echo
+		exit 1
+	fi
+
+	# Create a venv and activate it
+	PythonDir="$Cache/venv"
+	if [ ! -d "$PythonDir" ]; then
+		echo "Creating virtualenv..."
+		"$PythonExe" -m venv "$PythonDir"
+	fi
+	if [ -f "$PythonDir/bin/python" ]; then
+		PythonExe="$PythonDir/bin/python"
+	elif [ -f "$PythonDir/scripts/python3.exe" ]; then
+		PythonExe="$PythonDir/scripts/python3.exe";
+	else
+		echo "bootstrap/python failed to find the python executable inside its virtualenv"
+		exit 1
+	fi
+fi
+
+# Use pip to install our requirements
+if [ ! -f "$PythonDir/requirements.txt" ] || [ "$(b2sum < "$Sdk/requirements.txt")" != "$(b2sum < "$PythonDir/requirements.txt")" ]; then
+	echo "Updating dependencies..."
+	"$PythonExe" -m pip install -U wheel
+	"$PythonExe" -m pip install -U pip -r "$Sdk/requirements.txt"
+	cp "$Sdk/requirements.txt" "$PythonDir/requirements.txt"
+	echo "---"
+fi
+
+# Verify version and deduce the path separator
+PythonMajor=${PythonVersion%%.*}
+PythonMinor=${PythonVersion#*.}
+PythonMinor=${PythonMinor%.*}
+PATHSEP=$("$PythonExe" - "$PythonMajor" "$PythonMinor" <<'EOF'
+import sys, os
+if sys.version_info.major != int(sys.argv[1]) or sys.version_info.minor < int(sys.argv[2]):
+	print("Error: Python ", sys.argv[1], ".", sys.argv[2], " or later is required, but you have:\n", sys.version, sep="", file=sys.stderr)
+	exit(1)
+print(os.pathsep)
+EOF
+)
+
+# Cheap shell function if tee.exe is not available
+if ! command -v tee >/dev/null 2>&1; then
+	tee() {
+		# Fudge: assume $1 is always "-a"
+		while read -r line; do
+			echo "$line" >> "$2"
+			echo "$line"
+		done
+	}
+fi
+
+# Invoke python with all command-line arguments
+export PYTHONPATH="$Sdk$PATHSEP${PYTHONPATH:-}"
+mkdir -p "$Cache"
+printf '%s\n' "$PythonExe" "$@" > "$Log"
+printf -- '---\n' >> "$Log"
+exec 4>&1
+exitstatus=$({ { set +e; "$PythonExe" -u "$@" 2>&1 3>&-; printf %s $? >&3; } 4>&- | tee -a "$Log" 1>&4; } 3>&1)
+exec 4>&-
+exit "$exitstatus"