useful command

pw 1aA?

nohup command >/dev/null 2>&1   # doesn't create nohup.out
nohup ./a.out &

tail -f nohup.out
  -f, --follow[={name|descriptor}]
  output appended data as the file grows;
  an absent option argument means 'descriptor'

https://guides.github.com/
https://github.com/git-lfs/git-lfs/issues/911  Smudge filter failed with a fresh new clone
https://blog.csdn.net/weixin_34161029/article/details/86978708  ubuntu 设置开机自启动 / 设置定时重启 / crontab 定时执行 / 后台执行

https://www.cnblogs.com/darklights/p/7722861.html  Ubuntu 16.04安装Fcitx拼音输入法  fcitx-diagnose
https://blog.csdn.net/dlmu2001/article/details/8842891  strace
https://blog.csdn.net/chenbetter1996/article/details/85166528 vscode
sudo apt-get purge nvidia-*
g++ opmp.cc -fopenmp --verbose > ff 2>&1
sudo apt-get autoremove --purge

sudo add-apt-repository ppa:graphics-drivers
sudo apt-get update
sudo apt-get install nvidia-410 

  查看软件版本:     aptitude show xxx

  patch -p0 < geometry2_0.5.16_tf2.patch

http://www.brixbot.com/category/ros2/

  docker images|grep none|awk '{print $3 }'|xargs docker rmi

swap: 

837 dd if=/dev/zero of=/swap1 bs=1M count=2048
838 sudo dd if=/dev/zero of=/swap1 bs=1M count=16384
839 swapoff /swap1
840 sudo swapoff /swap1
841 sudo dd if=/dev/zero of=/swap1 bs=1M count=16384
842 mkswap /swap1
843 sudo mkswap /swap1
844 swapon /swap1
845 sudo swapon /swap1

sudo swapoff /swap1

Q:

root@ubuntu:/home/pipi# find / -perm -2000

/sbin/unix_chkpwd
find: `/home/pipi/.gvfs': 权限不够

A:

#umount /home/useraccount/.gvfs
#find . -inum 554009 -exec rm{} ;
After that,
#rm -rf .gvfs

Q:

通过终端安装程序sudo apt-get install xxx时出错：
E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable)
E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it

A:

出现这个问题可能是有另外一个程序正在运行，导致资源被锁不可用。而导致资源被锁的原因可能是上次运行安装或更新时没有正常完成，进而出现此状况，解决的办法其实很简单：

在终端中敲入以下两句
sudo rm /var/cache/apt/archives/lock
sudo rm /var/lib/dpkg/lock 

# 在源代码根目录，使用git status命令获取已修改文件的列表
git status | grep modified | awk '{print $2}' > list.txt
# 在当前目录下，创建temp目录
mkdir temp
# 将已修改文件列表逐一复制到当前目录下的temp目录
xargs -a ./list.txt cp --parents -t ./temp

# 将temp目录下的所有文件打包为modules.tar.gz
cd temp
tar -czf modules.tar.gz *
https://www.runoob.com/nodejs/nodejs-http-server.html

tinyxml2 https://blog.csdn.net/zhawk/article/details/60880036
https://csuyangpeng.slack.com/messages/CG9KY8199/
https://www.cnblogs.com/51kata/category/789766.html
http://dockone.io/article/128

在Ubuntu下，时不时会有这个错误的。 add-apt-repository: command not found

$ sudo apt-get install software-properties-common python-software-properties

ps -aux |grep distccd |grep -v grep|awk '{print $2}' |xargs kill -9
13316476216

075506010053@163.gd
https://stackoverflow.com/questions/7832770/how-to-get-certain-commit-from-github-project
scp yangpeng@10.9.139.171:/MOM/codeBuild02/yangpeng/45G/upSystem_v2.1_sz . 

　yangpeng@10.9.139.171's password:
　upSystem_v2.1_sz: not a regular file
　[root@localhost yp]# scp -r yangpeng@10.9.139.171:/MOM/codeBuild02/yangpeng/45G/upSystem_v2.1_sz .

 grep -rn "xxx" *

1、可以使用grep命令来查找当前目录下所有文件中包含的某个特定字符。

2、示例：查找当前目录下所有带有set的文件 。

说明：

-r 是递归查找

-n 是显示行号

* : 表示当前目录所有文件，也可以是某个文件名

find . -name  "*.cc"

find ./ -name "*.java" -o -name "*.xml"

 Google C++ Style Guide

https://google.github.io/styleguide/cppguide.html#Constant_Names

https://github.com/ApolloAuto/apollo/tree/apollo  csuyangpeng0308

http://wiki.ros.org/rosbag/Code%20API#cpp_api

moonx@moonx:/usr/download/boost_1_42_0/pro$ cat test_header.cpp 
#include<nonexist.h> // This is a non-existant system header
 
int main ( int argc, char* argv[] )
{
    return 0;
}
moonx@moonx:/usr/download/boost_1_42_0/pro$ g++ -c -v test_header.cpp 
Using built-in specs.
COLLECT_GCC=g++
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 5.4.0-6ubuntu1~16.04.11' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs --enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-5 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.11) 
COLLECT_GCC_OPTIONS='-c' '-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
 /usr/lib/gcc/x86_64-linux-gnu/5/cc1plus -quiet -v -imultiarch x86_64-linux-gnu -D_GNU_SOURCE test_header.cpp -quiet -dumpbase test_header.cpp -mtune=generic -march=x86-64 -auxbase test_header -version -fstack-protector-strong -Wformat -Wformat-security -o /tmp/ccmXkUCU.s
GNU C++ (Ubuntu 5.4.0-6ubuntu1~16.04.11) version 5.4.0 20160609 (x86_64-linux-gnu)
    compiled by GNU C version 5.4.0 20160609, GMP version 6.1.0, MPFR version 3.1.4, MPC version 1.0.3
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring duplicate directory "/usr/include/x86_64-linux-gnu/c++/5"
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/5/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/download/boost_1_42_0
 .
 /usr/include/c++/5
 /usr/include/x86_64-linux-gnu/c++/5
 /usr/include/c++/5/backward
 /usr/lib/gcc/x86_64-linux-gnu/5/include
 /usr/local/include
 /usr/lib/gcc/x86_64-linux-gnu/5/include-fixed
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
GNU C++ (Ubuntu 5.4.0-6ubuntu1~16.04.11) version 5.4.0 20160609 (x86_64-linux-gnu)
    compiled by GNU C version 5.4.0 20160609, GMP version 6.1.0, MPFR version 3.1.4, MPC version 1.0.3
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 8c2b43f572cd3f060e41aeab70254763
test_header.cpp:1:61: fatal error: nonexist.h: 没有那个文件或目录
compilation terminated.
moonx@moonx:/usr/download/boost_1_42_0/pro$ 

1 编译链接：动态库 静态库 
   gcc编译线程程序，为什么要加-lpthread，头文件已经包含了<pthread.h>了啊
 2 
 3 编译程序包括 预编译， 编译，汇编，链接
 4 包含头文件了，仅能说明有了线程函数的声明， 但是还没有实现， 加上-lpthread是在链接阶段，链接这个库
 5 
 6 谢谢。那其它的呢？很多比如<stdio.h>  <sys/ipc.h>   <sys/sem.h>    <sys/shm.h>。还有很多，都不要加，难道就<pthread.h>比较特别？？？
 7 
 8 其他的可能包含在默认链接的库中，如libc, 其他不清楚，很少写linux代码，忘的差不多了
 9 
10 &lt;stdio.h&gt;等都是静态库，不需要做额外的表示，连接时会直接链接进代码里。pthread是动态库，需要用-lpthread，所有的动态库都需要用-lxxx来引用 

1. 本地分支重命名
git branch -m oldbranchname newbranchname

支持C++11特性：gcc -g -Wall -std=c11 main.cpp

创建tar.xz文件：只要先 tar cvf xxx.tar xxx/ 这样创建xxx.tar文件先，然后使用 xz -z xxx.tar 来将 xxx.tar压缩成为 xxx.tar.xz

解压tar.xz文件：先 xz -d xxx.tar.xz 将 xxx.tar.xz解压成 xxx.tar 然后，再用 tar xvf xxx.tar来解包。

https://bigsearcher.com/mirrors/gcc/releases/gcc-8.2.0/

gcc-8.1.0安装

tar -Jxvf gcc-8.1.0.tar.xz

cd gcc-8.1.0 ./contrib/download_prerequisites

cd .. mkdir temp_gcc81 && cd temp_gcc81

../gcc-8.1.0/configure --prefix=/usr/local/gcc-8.1 --enable-threads=posix --disable-checking --disable-multilib

#error "Unable to find a suitable type for HOST_WIDE_INT"

unset LIBRARY_PATH CPATH C_INCLUDE_PATH PKG_CONFIG_PATH CPLUS_INCLUDE_PATH INCLUDE

make

sudo make install 

---

adding-public-key-to-ssh-authorized-keys-does-not-log-me-in-automatically

https://stackoverflow.com/questions/6377009/adding-public-key-to-ssh-authorized-keys-does-not-log-me-in-automatically

You need to verify the permissions of the authorized_keys file and the folder / parent folders in which it is located.

chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys

For more information see this page.

You may also need to change/verify the permissions of your home directory to remove write access for the group and others.

chmod go-w ~ 

moonx@MoonXComputer:~/.ssh$ ssh -v moonx@192.168.4.74
OpenSSH_7.2p2 Ubuntu-4ubuntu2.7, OpenSSL 1.0.2g  1 Mar 2016
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug1: Connecting to 192.168.4.74 [192.168.4.74] port 22.
debug1: Connection established.
debug1: identity file /home/moonx/.ssh/id_rsa type 1
debug1: key_load_public: No such file or directory
debug1: identity file /home/moonx/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/moonx/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/moonx/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/moonx/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/moonx/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/moonx/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/moonx/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.7
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.2p2 Ubuntu-4ubuntu2.7
debug1: match: OpenSSH_7.2p2 Ubuntu-4ubuntu2.7 pat OpenSSH* compat 0x04000000
debug1: Authenticating to 192.168.4.74:22 as 'moonx'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: curve25519-sha256@libssh.org
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none
debug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:scmIqSf23TCO6MoFBWwq7bswmg+luMjjb14FkAm157o
debug1: Host '192.168.4.74' is known and matches the ECDSA host key.
debug1: Found key in /home/moonx/.ssh/known_hosts:1
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<rsa-sha2-256,rsa-sha2-512>
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /home/moonx/.ssh/id_rsa
debug1: Server accepts key: pkalg rsa-sha2-512 blen 279
debug1: Authentication succeeded (publickey).
Authenticated to 192.168.4.74 ([192.168.4.74]:22).
debug1: channel 0: new [client-session]
debug1: Requesting no-more-sessions@openssh.com
debug1: Entering interactive session.
debug1: pledge: network
debug1: client_input_global_request: rtype hostkeys-00@openssh.com want_reply 0
debug1: Sending environment.
debug1: Sending env LC_PAPER = zh_CN.UTF-8
debug1: Sending env LC_ADDRESS = zh_CN.UTF-8
debug1: Sending env LC_MONETARY = zh_CN.UTF-8
debug1: Sending env LC_NUMERIC = zh_CN.UTF-8
debug1: Sending env LC_TELEPHONE = zh_CN.UTF-8
debug1: Sending env LC_IDENTIFICATION = zh_CN.UTF-8
debug1: Sending env LANG = en_US.UTF-8
debug1: Sending env LC_MEASUREMENT = zh_CN.UTF-8
debug1: Sending env LC_TIME = zh_CN.UTF-8
debug1: Sending env LC_NAME = zh_CN.UTF-8
Welcome to Ubuntu 16.04.5 LTS (GNU/Linux 4.15.0-45-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

8 packages can be updated.
0 updates are security updates.

New release '18.04.1 LTS' available.
Run 'do-release-upgrade' to upgrade to it.

Last login: Fri Feb 15 17:42:00 2019 from 127.0.0.1


gssapi-keyex,gssapi-with-mic,

 linux服务器查看公网IP信息的方法

最近在解决网络问题时，需要查看本机的出口公网IP信息，所以在网络上搜索和请求运维达人，获得如下两个方法：curl ifconfig.me

在linux系统中输入上述的命令，可以查看到本机连接的公网信息；如果该命令无效，可以使用下面一个命令，也同样可以获得对应的信息 curl cip.cc https://blog.csdn.net/gebitan505/article/details/14448429