Hide current working directory in terminal

 

do it on your terminal

$ export OLD_PS1=$PS1                    # save Long Prompt to OLD_PS1
$ export PS1="\u > "export PS1="\u $ "   # change to PS1 to Short Prompt
$ export PS1=$OLD_PS1                    # restore Long Prompt to PS1

curlpp/cURLpp.hpp: No such file or directory

issue: 

curlpp/cURLpp.hpp: No such file or directory

solution:

install package which related with curl

> sudo apt-get install pkg-config libcurlpp-dev libcurl4-openssl-dev

* Check header file location

> dpkg -S cURLpp.hpp

libcurlpp-dev:amd64: /usr/include/curlpp/cURLpp.hpp

Thank you.

study.marearts.com

marearts

C linux get Mac Address

 In my case, I failed to get Mac from eth0 devices.

So I need to check all devices to get Mac address.

This is my solution example code:

(study.marearts.com)

..

#include <sys/ioctl.h>

#include <net/if.h>

#include <unistd.h>

#include <netinet/in.h>

#include <string.h>

#include <stdio.h>

#include <sstream>

#include <string>

#include <iostream>

std::string getMac(){

struct ifreq ifr;

struct ifconf ifc;

char buf[1024];

int success = 0;

int sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);

if (sock == -1) { /* handle error*/ };

ifc.ifc_len = sizeof(buf);

ifc.ifc_buf = buf;

if (ioctl(sock, SIOCGIFCONF, &ifc) == -1) { /* handle error */ }

struct ifreq* it = ifc.ifc_req;

const struct ifreq* const end = it + (ifc.ifc_len / sizeof(struct ifreq));

int a=0;

for (; it != end; ++it) {

strcpy(ifr.ifr_name, it->ifr_name);

if (ioctl(sock, SIOCGIFFLAGS, &ifr) == 0) {

if (! (ifr.ifr_flags & IFF_LOOPBACK)) { // don't count loopback

if (ioctl(sock, SIOCGIFHWADDR, &ifr) == 0) {

success = 1;

break;

}

}

}

else {

/* handle error */

return "0";

}

}

unsigned char mac_address[6];

if (success)

{

memcpy(mac_address, ifr.ifr_hwaddr.sa_data, 6);

std::stringstream ss;

std::string target;

char buffer [50];

sprintf (buffer, "%x-%x-%x-%x-%x-%x", mac_address[0], mac_address[1], mac_address[2], mac_address[3], mac_address[4], mac_address[5]);

ss << buffer;

ss >> target;

return target;

}

return "0";

}

int main()

{

std::cout<< getMac() << std::endl;

}

..

Output is

44-a5-6e-63-a4-bb

Thank you.

marearts

python date time add or subtract

datetime package is very useful.

see the example code..

..

import datetime

print(datetime.datetime.now())

print(datetime.datetime.now().date())

lastHourDateTime = datetime.datetime.now() + datetime.timedelta(days = +10)

print(lastHourDateTime.date())

print(lastHourDateTime.time())

lastHourDateTime = datetime.datetime.now() + datetime.timedelta(hours = 10)

print(lastHourDateTime.date())

print(lastHourDateTime.time())

lastHourDateTime = datetime.datetime.now() + datetime.timedelta(hours = -10)

print(lastHourDateTime.date())

print(lastHourDateTime.time())

..

result

2021-07-08 10:19:44.969082

2021-07-08

2021-07-18

10:19:44.969146

2021-07-08

20:19:44.969164

Thank you.

study.marearts.com

opencv Vector CameraParams save(yaml file store) and load(yaml file restore ) using FileNode, FileNodeIterator

Refer to load & save function.

..

std::vector<cv::detail::CameraParams> params;

bool loadCameraParams(std::string fileName){

cv::FileStorage fs(fileName+".yaml", cv::FileStorage::READ);

if(!fs.isOpened())

return false;

/////

int nObjects= 0;

fs["NC"] >> nObjects;

params.clear();

params.resize(nObjects);

/////

cv::FileNode fn = fs["cameras"];

int id=0;

for (cv::FileNodeIterator it = fn.begin(); it != fn.end(); it++,id++)

{

cv::FileNode item = *it;

cv::Mat K, R, t;

double ppx, ppy, focal, aspect;

item["K"] >> K;

item["R"] >> R;

item["t"] >> t;

item["ppx"] >> ppx;

item["ppy"] >> ppy;

item["focal"] >> focal;

item["aspect"] >> aspect;

mg_params[id].K() = (cv::Mat)K;

mg_params[id].R = R;

mg_params[id].t = t;

mg_params[id].ppx = (double)ppx;

mg_params[id].ppy = (double)ppy;

mg_params[id].focal = (double)focal;

mg_params[id].aspect = (double)aspect;

}

return true;

}

bool saveCameraParams(std::string fileName){

cv::FileStorage fs(fileName+".yaml", cv::FileStorage::WRITE);

cv::detail::CameraParams cameras = mg_params[0];

fs << "NC" << int(params.size());

fs << "cameras" << "[";

for (const auto& param : mg_params)

{

fs << "{";

fs << "K" << param.K();

fs << "R" << param.R;

fs << "t" << param.t;

fs << "ppx" << param.ppx;

fs << "ppy" << param.ppy;

fs << "focal" << param.focal;

fs << "aspect" << param.aspect;

fs << "}";

}

fs << "]";

fs.release();

return true;

}

..

Thank you!!

☕️

bash: g++: command not found

 > sudo apt-get install g++

main.cpp:(.text+0x3f): undefined reference to `std::ios_base::Init::Init()'

 errors like that:

> gcc -o test main.cpp 

/usr/bin/ld: /tmp/ccoMmwaL.o: in function `__static_initialization_and_destruction_0(int, int)':

main.cpp:(.text+0x3f): undefined reference to `std::ios_base::Init::Init()'

/usr/bin/ld: main.cpp:(.text+0x54): undefined reference to `std::ios_base::Init::~Init()'

collect2: error: ld returned 1 exit status

just replace g++ instead of gcc

> g++ -o test main.cpp 

Then it would be fine!.

Thank you!