[Dev] Create a script for building dgl from source. (#5294)

Co-authored-by: Ubuntu <ubuntu@ip-172-31-28-63.ap-northeast-1.compute.internal>

script/build_dgl.sh

+#!/bin/bash
+
+set -e
+
+usage() {
+cat << EOF
+usage: bash $0 OPTIONS
+examples:
+  Start a CPU only build: bash $0 -c
+  Start a CUDA build: bash $0 -g
+  Build incrementally: bash $0
+  Remove all intermediate output and restart a CPU only build: bash $0 -c -r
+
+Build DGL. By default, build incrementally on top of the current state.
+
+OPTIONS:
+  -h           Show this message.
+  -c           Restart CPU only build.
+  -g           Restart CUDA build.
+  -r           Remove all intermediate output.
+EOF
+}
+
+# Parse flags.
+while getopts "cghr" flag; do
+  if [[ ${flag} == "c" ]]; then
+    cuda="OFF"
+  elif [[ ${flag} == "g" ]]; then
+    cuda="ON"
+  elif [[ ${flag} == "r" ]]; then
+    remove="YES"
+  elif [[ ${flag} == "h" ]]; then
+    usage
+    exit 0
+  else
+    usage
+    exit 1
+  fi
+done
+
+if [[ -z ${DGL_HOME} ]]; then
+  echo "ERROR: Please make sure environment variable DGL_HOME is set correctly."
+  exit 1
+fi
+
+if [[ ! ${PWD} == ${DGL_HOME} ]]; then
+  echo "ERROR: This script only works properly from DGL root directory."
+  echo " Current: ${PWD}"
+  echo "DGL_HOME: ${DGL_HOME}"
+  exit 1
+fi
+
+if [[ ${remove} == "YES" ]]; then
+  rm -rf build
+fi
+
+if [[ -z ${cuda} ]]; then
+  if [[ -d build ]]; then
+    cd build
+  else
+    echo "ERROR: No existing build status found, unable to build incrementally."
+    usage
+    exit 1
+  fi
+else
+  mkdir -p build
+  cd build
+  cmake -DUSE_CUDA=${cuda} ..
+fi
+
+if [[ ${PWD} == "${DGL_HOME}/build" ]]; then
+  make -j
+else
+  echo "ERROR: unexpected working directory."
+  echo " Current: ${PWD}"
+  echo "Expected: ${DGL_HOME}/build"
+fi
+exit 0