ci / gh-actions : update linux build script

The script is tested on my computer with zsh, qt 5.15.2

ci/linux/build_for_ubuntu.sh

@@ -1,85 +1,67 @@
-
-echo
-echo
 echo ---------------------------------------------------------------
-echo check ENV
+echo Check \& Set Environment Variables
 echo ---------------------------------------------------------------
 
-# 从环境变量获取必要参数
-# 例如 /home/barry/Qt5.9.6/5.9.6
-echo ENV_QT_PATH $ENV_QT_PATH
+# Get Qt path
+# ENV_QT_PATH example: /home/barry/Qt5.9.6/5.9.6
+echo Current ENV_QT_PATH: $ENV_QT_PATH
+echo Current directory: $(pwd)
+# Set variables
 qt_cmake_path=$ENV_QT_PATH/gcc_64/lib/cmake/Qt5
+export PATH=$qt_gcc_path/bin:$PATH
 
-# 获取绝对路径，保证其他目录执行此脚本依然正确
-{
-cd $(dirname "$0")
-script_path=$(pwd)
-cd -
-} &> /dev/null # disable output
-# 设置当前目录，cd的目录影响接下来执行程序的工作目录
+# Remember working directory
 old_cd=$(pwd)
-cd $(dirname "$0")
 
-# 启动参数声明
-build_mode=RelWithDebInfo
+# Set working dir to the script's path
+cd $(dirname "$0")/.../
 
 echo
 echo
 echo ---------------------------------------------------------------
-echo check build param[Debug/Release/MinSizeRel/RelWithDebInfo]
+echo Check Build Parameters
 echo ---------------------------------------------------------------
+echo Possible build modes: Debug/Release/MinSizeRel/RelWithDebInfo
 
-# 编译参数检查
-build_mode=$(echo $1)
+build_mode="$1"
 if [[ $build_mode != "Release" && $build_mode != "Debug" && $build_mode != "MinSizeRel" && $build_mode != "RelWithDebInfo" ]]; then
-    echo "error: unkonow build mode -- $1"
+    echo "error: unknown build mode, exiting......"
     exit 1
 fi
 
-# 提示
-echo current build mode: $build_mode
-
-# 环境变量设置
-#export PATH=$qt_gcc_path/bin:$PATH
+echo Current build mode: $build_mode
 
 echo
 echo
 echo ---------------------------------------------------------------
-echo begin cmake build
+echo CMake Build Begins
 echo ---------------------------------------------------------------
 
-# 删除输出目录
-output_path=$script_path../../output
+# Remove output folder
+output_path=./output
 if [ -d "$output_path" ]; then
     rm -rf $output_path
 fi
-# 删除临时目录
-build_path=$script_path/../build_temp
-if [ -d "$build_path" ]; then
-    rm -rf $build_path
-fi
-mkdir $build_path
-cd $build_path
 
 cmake_params="-DCMAKE_PREFIX_PATH=$qt_cmake_path -DCMAKE_BUILD_TYPE=$build_mode"
-cmake $cmake_params ../..
+cmake $cmake_params .
 if [ $? -ne 0 ] ;then
-    echo "cmake failed"
+    echo "error: CMake failed, exiting......"
     exit 1
 fi
 
-cmake --build . --config $build_mode -j8
+cmake --build . --config "$build_mode" -j8
 if [ $? -ne 0 ] ;then
-    echo "cmake build failed"
+    echo "error: CMake build failed, exiting......"
     exit 1
 fi
 
 echo
 echo
 echo ---------------------------------------------------------------
-echo finish!!!
+echo CMake Build Succeeded
 echo ---------------------------------------------------------------
 
-# 恢复当前目录
+# Resume current directory
 cd $old_cd
 exit 0