喵哥前段时间尝试在centos6上安装YCM失败了，主要是因为众多依赖软件的版本太低，搞得喵哥全无兴致，好歹也是记录了一下路上遇到的坑位。详情可以到：
centos6.10安装VIM插件YOUCOMPLETEME的坑位标记
参考。
今天，喵哥打算把宿舍笔记本的vim给配置了。
笔记本的系统是Ubuntu18.04，之前用的时候把机器上的vim、Python都更新了一遍，目前的状况大致如下：
| 软件 | 版本 |
| Python | 3.7.1 |
| gcc | 7.3.0 |
| vim | 8.0 |
| git | 2.17.1 |
| cmake | 未安装 |
| llvm | 未安装 |
除了cmake外、llvm，其余的版本在我印象中是够用了，这些软件的安装教程在网上还是蛮多的，如果发现自己的版本不对，建议先去安装好。
先安装cmake：
wget --no-check-certificate https://cmake.org/files/v3.8/cmake-3.8.0-rc2.tar.gz
tar xf cmake-3.8.0-rc2.tar.gz
cd cmake-3.8.0-rc2
./bootstrap
make -j 4
sudo make install 插一句，make的时候用-j 4加速是真的爽，之前一直在单核的容器中跑，用-j 4反而更慢。
安装llvm
mkdir llvm-3.9.1
cd llvm-3.9.1
wget http://releases.llvm.org/3.9.1/llvm-3.9.1.src.tar.xz
wget http://releases.llvm.org/3.9.1/cfe-3.9.1.src.tar.xz
wget http://releases.llvm.org/3.9.1/compiler-rt-3.9.1.src.tar.xz
wget http://releases.llvm.org/3.9.1/clang-tools-extra-3.9.1.src.tar.xz
编译lang，
要记得先把gcc、python、camke安装好
。
tar xf llvm-3.9.1.src.tar.xz
tar xf clang-tools-extra-3.9.1.src.tar.xz
tar xf compiler-rt-3.9.1.src.tar.xz
tar xf cfe-3.9.1.src.tar.xz
mv cfe-3.9.1.src llvm-3.9.1.src/tools/clang
mv clang-tools-extra-3.9.1.src llvm-3.9.1.src/tools/clang/tools/extra
mv compiler-rt-3.9.1.src llvm-3.9.1.src/projects/compiler-rt
cmake -G"Unix Makefiles" -DCMAKE_INSTALL_PREFIX=$HOME/clang3.9 -DCMAKE_BUILD_TYPE=Release -DLLVM_TARGETS_TO_BUILD="X86" llvm-3.9.1.src && make -j 4#2019.7.3
安装好lang之后，在编译YCM的时候还是出了点问题：
Downloading libclang 8.0.0 from https://dl.bintray.com/micbou/libclang/libclang-8.0.0-x86_64-unknown-linux-gnu.tar.bz2
CMake Error at ycm/CMakeLists.txt:107 (file):
file DOWNLOAD HASH mismatch
for file: [/home/catlincao/.vim/plugged/YouCompleteMe/third_party/ycmd/cpp/../clang_archives/libclang-8.0.0-x86_64-unknown-linux-gnu.tar.bz2]
expected hash: [e81a186cd1180ae80c17d67d8d0c101248f8ee032d138cf6f1e95001e733249c]
actual hash: [e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855]
status: [1;"Unsupported protocol"]
CMake Error at ycm/CMakeLists.txt:123 (message):
Cannot find path to libclang in prebuilt binaries
-- Configuring incomplete, errors occurred!
See also "/tmp/ycm_build_h6en0mfh/CMakeFiles/CMakeOutput.log".
ERROR: the build failed.按照提示，手动下载libclang 8.0.0
wget https://dl.bintray.com/micbou/libclang/libclang-8.0.0-x86_64-unknown-linux-gnu.tar.bz2把下载的文件放到~/.vim/plugged/YouCompleteMe/third_party/ycmd/clang_archives下。就ok了
从github上下载Vundle
git clone https://github.com/VundleVim/Vundle.vim.git ~/.vim/bundle/Vundle.vim
以官方（
https://github.com/VundleVim/Vundle.vim
）的提供的.vimrc作为初始模板做了部分添加，主角是：
Plugin ‘Valloric/YouCompleteMe’
.vimrc通常保存在当前用户的目录下，便于管理。其实在/etc/vim目录下有一个vimrc的全局配置文件，也可以在这里添加vim的配置命令。喵哥把文件保存在～/下，vim ~/.vimrc。
set nocompatible " be iMproved, required
filetype off " required
set nu
set hls
syntax enable
syntax on
set ruler
" set the runtime path to include Vundle and initialize
set rtp+=~/.vim/bundle/Vundle.vim
call vundle#begin()
" alternatively, pass a path where Vundle should install plugins
"call vundle#begin('~/some/path/here')
" let Vundle manage Vundle, required
Plugin 'VundleVim/Vundle.vim'
" The following are examples of different formats supported.
" Keep Plugin commands between vundle#begin/end.
" plugin on GitHub repo
Plugin 'tpope/vim-fugitive'
" plugin from http://vim-scripts.org/vim/scripts.html
" Plugin 'L9'
" Git plugin not hosted on GitHub
Plugin 'git://git.wincent.com/command-t.git'
" git repos on your local machine (i.e. when working on your own plugin)
Plugin 'file:///home/gmarik/path/to/plugin'
" The sparkup vim script is in a subdirectory of this repo called vim.
" Pass the path to set the runtimepath properly.
Plugin 'rstacruz/sparkup', {'rtp': 'vim/'}
" Install L9 and avoid a Naming conflict if you've already installed a
" different version somewhere else.
" Plugin 'ascenator/L9', {'name': 'newL9'}
"YCM
Plugin 'Valloric/YouCompleteMe'
" All of your Plugins must be added before the following line
call vundle#end() " required
filetype plugin indent on " required
" To ignore plugin indent changes, instead use:
"filetype plugin on
"
" Brief help
" :PluginList - lists configured plugins
" :PluginInstall - installs plugins; append `!` to update or just :PluginUpdate
" :PluginSearch foo - searches for foo; append `!` to refresh local cache在终端输入vim，进入到vim在普通模式（非插入模式）下输入
:PluginInstall
报错Not an editor command: PluginInstall，执行git clone https://github.com/gmarik/Vundle.vim.git ~/.vim/plugin/Vundle.vim解决
就可以开始下载.vimrc中配置的插件了，如果想快点的话，可以只在配置文件中保留
Plugin 'Valloric/YouCompleteMe'下载YCM的大小是303M左右，为了查看下载进度，可以用
du -h ~/.vim/bundle/YouCompleteMe查看下载了多少。
下载YCM完成后，进入到YCM的目录下，开始安装：
cd ~/.vim/bundle/YouCompleteMe
./install.py --clang-completer
安装成功后，在~/.vimrc中添加：
" YouCompleteMe
set runtimepath+=~/.vim/bundle/YouCompleteMe
let g:ycm_collect_identifiers_from_tags_files = 1 " 开启 YCM 基于标签引擎
let g:ycm_collect_identifiers_from_comments_and_strings = 1 " 注释与字符串中的内容也用于补全
let g:syntastic_ignore_files=[".*\.py$"]
let g:ycm_seed_identifiers_with_syntax = 1 " 语法关键字补全
let g:ycm_complete_in_comments = 1
let g:ycm_confirm_extra_conf = 0
let g:ycm_key_list_select_completion = ['<c-n>', '<Down>'] " 映射按键, 没有这个会拦截掉tab, 导致其他插件的tab不能用.
let g:ycm_key_list_previous_completion = ['<c-p>', '<Up>']
let g:ycm_complete_in_comments = 1 " 在注释输入中也能补全
let g:ycm_complete_in_strings = 1 " 在字符串输入中也能补全
let g:ycm_collect_identifiers_from_comments_and_strings = 1 " 注释和字符串中的文字也会被收入补全
let g:ycm_global_ycm_extra_conf='~/.ycm_extra_conf.py'
let g:ycm_show_diagnostics_ui = 0 " 禁用语法检查我把YCM的配置文件放在当前用户根目录下，这里原本是没有的文件的，自己添加就好了：
vim ~/.ycm_extra_conf.py由于喵哥主要用C++，所以这里暂时添加C++的相关项目：
flags = [
'-Wall',
'-Wextra',
'-Werror',
'-Wno-long-long',
'-Wno-variadic-macros',
'-fexceptions',
'-DNDEBUG',
'-std=c++11',
'-x',
'c++',
'-I',
'/usr/include',
'-isystem',
'/usr/lib/gcc/x86_64-linux-gnu/5/include',
'-isystem',
'/usr/include/x86_64-linux-gnu',
'-isystem'
'/usr/include/c++/5',
'-isystem',
'/usr/include/c++/5/bits'
]对于vim找不到的头文件就可以在这里面添加路径。
到这里基本YCM就配置好了，Ctrl+Space弹出补全对象，Ctrl+J跳转至定义处。
孤陋寡闻了，很墙裂地推荐大家参考这两篇文章，真的很强！
https://www.jianshu.com/p/75cde8a80fd7
https://blog.csdn.net/Mason_Mao/article/details/80984726