前言

以下將為Debian 8 (Jessie) 編譯安裝qBittorrent。
教學分為依賴包安裝與編譯qBittorrent/libtorrent兩部份
通過測試於qBitorrent 4.1.5
2019/03/26更新：通過測試於libtorrent 1.1.12 1.2.0 / qBittorrent 4.1.5 4.2.0a

適用於Ubuntu18/Debian9的教學：https://npchk.info/ubuntu-debian-install-qbittorrent/

參考資料：
https://tieba.baidu.com/p/5570353699
https://amefs.net/archives/1613.html
感謝 wdsr20001202 Mimi客 彼音星垠 AMEFS

安裝工具和軟件包

安裝編譯GCC Boost Qt libtorrent qBittorrent的所需組件：

apt update
apt install build-essential pkg-config automake libtool git screen libgeoip-dev python3 libgl1-mesa-dev python3-dev libicu-dev libbz2-dev libssl-dev zlib1g-dev

接下來需要編譯的軟件體積巨大且耗時，源碼編譯後約佔10GB空間。
編譯安裝GCC：

wget https://ftp.gnu.org/gnu/gcc/gcc-7.3.0/gcc-7.3.0.tar.xz
tar xf gcc-7.3.0.tar.xz
cd gcc-7.3.0
./contrib/download_prerequisites
mkdir objdir
cd objdir
../configure --enable-checking=release --enable-languages=c,c++ --disable-multilib
make -j$(nproc)
make install
cp /usr/local/lib64/libstdc++.so.6.0.24 /usr/lib/x86_64-linux-gnu/
rm /usr/lib/x86_64-linux-gnu/libstdc++.so.6
ln -s /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.24 /usr/lib/x86_64-linux-gnu/libstdc++.so.6
cd ../.. && rm -rf gcc-7.3.0

編譯安裝Boost：

wget https://dl.bintray.com/boostorg/release/1.65.1/source/boost_1_65_1.tar.bz2
tar xf boost_1_65_1.tar.bz2
cd boost_1_65_1
./bootstrap.sh --with-libraries=all --prefix=/usr/local
./b2 -j$(nproc) toolset=gcc
./b2 install
ldconfig
cd .. && rm -rf boost_1_65_1

編譯安裝Qt：

wget https://download.qt.io/archive/qt/5.9/5.9.5/single/qt-everywhere-opensource-src-5.9.5.tar.xz
tar xf qt-everywhere-opensource-src-5.9.5.tar.xz
cd qt-everywhere-opensource-src-5.9.5
./configure -release -opensource -confirm-license -strip -shared -ltcg -make libs -make tools -dbus -nomake examples -no-compile-examples -no-qml-debug -no-icu -no-gtk -no-opengles3 -no-angle -no-sql-sqlite -no-sql-odbc -no-sqlite -skip qt3d -skip qtactiveqt -skip qtandroidextras -skip qtcanvas3d -skip qtcharts -skip qtconnectivity -skip qtdatavis3d -skip qtdoc -skip qtgamepad -skip qtgraphicaleffects -skip qtimageformats -skip qtlocation -skip qtmacextras -skip qtmultimedia -skip qtnetworkauth -skip qtpurchasing -skip qtquickcontrols -skip qtquickcontrols2 -skip qtremoteobjects -skip qtscript -skip qtscxml -skip qtsensors -skip qtserialbus -skip qtserialport -skip qtspeech -skip qtvirtualkeyboard -skip qtwayland -skip qtwebchannel -skip qtwebengine -skip qtwebsockets -skip qtwebview -skip qtx11extras -skip qtxmlpatterns
make -j$(nproc)
make install
cd .. && rm -rf qt-everywhere-opensource-src-5.9.5

###如果出現錯誤：ERROR: The OpenGL functionality tests failed!
可嘗試在./configure加參數 -no-opengl 

Qt將安裝在 /usr/local/Qt-5.9.5，設置環境變量：

nano /etc/profile

添加內容

export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig:/usr/local/Qt-5.9.5/lib/pkgconfig
export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/Qt-5.9.5/bin

設置生效

source /etc/profile

安裝libtorrent：

wget https://github.com/arvidn/libtorrent/releases/download/libtorrent_1_1_12/libtorrent-rasterbar-1.1.12.tar.gz
tar xf libtorrent-rasterbar-1.1.12.tar.gz
cd libtorrent-rasterbar-1.1.12
./configure --disable-debug --enable-encryption --with-libgeoip=system CXXFLAGS=-std=c++11
make -j$(nproc)
make install
ldconfig
cd .. && rm -rf libtorrent-rasterbar-1.1.12

編譯安裝qBittorrent

https://github.com/qbittorrent/qBittorrent/releases

wget https://github.com/qbittorrent/qBittorrent/archive/release-4.1.5.tar.gz
tar xf release-4.1.5.tar.gz
cd qBittorrent-release-4.1.5
./configure --disable-gui --disable-debug
make -j$(nproc)
make install

設置開機自啟

nano /etc/systemd/system/qbittorrent.service

輸入以下內容：

[Unit]
Description=qBittorrent Daemon Service
After=network.target

[Service]
LimitNOFILE=512000
User=root
ExecStart=/usr/local/bin/qbittorrent-nox
ExecStop=/usr/bin/killall -w qbittorrent-nox

[Install]
WantedBy=multi-user.target

啟用以上設置：

systemctl enable qbittorrent.service

啟動qBittorrent(首次啟動請按y確認條款)

qbittorrent-nox

按Ctrl+C退出

後台運行qBittorrent:

systemctl start qbittorrent.service

安裝完成

訪問WebUI：http://你的IPADDRESS:8080/
默認用戶名：admin
默認密碼：adminadmin
關閉qBittorrent命令: systemctl stop qbittorrent.service
啟動qBittorrent命令: systemctl start qbittorrent.service
重啟qBittorrent命令: systemctl restart qbittorrent.service

創建下載文件夾和設置權限

mkdir /home/Downloads
chmod 777 /home/Downloads

把下載路徑設置到/home/Downloads就OK了！