Tue, Sep 21, 2021

British vs American

• flat - appartment
• congestion - traffic jam
• take away - to go

TIL

Names that begin with either ‘is’ or ‘to’ followed by a lowercase letter reserved by POSIX.

Link to the manual

Issues with HTC Vive

• headphone jack lose sometimes and one ear stop work
• HDMI fall off
• the base station broke; it always showed blue light
• headphones stopped working
• audio left and right ears sometimes swapped
• one out of 3 trackers refuses to turn on sometimes
• hard to find the side button on HDMI, but very easy to press it by assident

Common Chord progressions

I – iV – V7
I – V – vi – IV
I – vi – IV – V
I – V – vi – iii – IV – I – IV – V
I – IV – V – I
I – I – I – I – IV – IV – I – I – V – V – I – I
I – IV – V – IV

ii – IV – V
V – IV – I
vi – IV – I – V
vi – V – IV – III
vi – V – VI – V
ii – I – V6 – bVII

TIL

// clang-format on
// clang-format off

My dream job at 2007 (10 years ago)

In office:

• ☑ salary $3 000 or more
• ☐ big bright office
• ☐ at winter warm and at summer cool
• ☑ clean restroom
• ☑ no cigarette smoke
• ☑ hot water in the sink
• ☑ mirror in the restroom
• ☐ sofa
• ☑ tea
• ☑ trash-bin near by the desktop
• ☑ free classes
• ☐ ability to pick your own specification for the computer
• ☑ licensed software
• ☐ floating hours

WFH

• ☑ salary $3,000 or more
• ☑ big bright office
• ☐ at winter warm and at summer cool
• ☐ clean restroom
• ☑ no cigarette smoke
• ☑ hot water in the sink
• ☑ mirror in the restroom
• ☑ sofa
• ☑ tea
• ☐ trash-bin near by the desktop
• ☑ free classes
• ☑ ability to pick your own specification for the computer
• ☑ licensed software
• ☐ floating hours

My current dream job

• ☐ work on my own ideas
• ☐ be able to drop the project at any time
• ☐ be able to start any project at any time
• ☐ travel (carry with me in the luggage my PC setup with 2 big screens and VR setup), have high speed internet while I am traveling
• ☑ work from home
• ☑ big bright office
• ☐ at winter warm and at summer cool
• ☐ floating hours
• ☐ no planning
• ☐ make technical decisions
• ☐ I want to have a team, and they will do exactly what I asked them to do without any questions and complaining
• ☑ program in C++
• ☑ working on making games
• ☐ be able to stream on Twitch my work

Play video using VDPAU decoder

mplayer -vo vdpau and -vc ffh264vdpau,ffmpeg12vdpau,ffwmv3vdpau,ffvc1vdpau -ao alsa file.mp4

Ideal game engine

• C++ (including scripting on C++)
• Multiplatform (Linux, Mac, iOS, Android)
• Licence (free and I can use the engine for publishing games on AppStore and Google Play)
• Good tutorials

How to upload file using linux command tool ftp

$ ftp host Connected to host (10.139.88.123). 220 (vsFTPd 3.0.2) Name (host:user): user 331 Please specify the password. Password: password ftp> cd path ftp> put localfile remotepath

How to make SSH tunnel

      local   ssh connection   remote1       remote2
             o--------------->o
              +------------->+
              ^              v
TCP port [L]o-+              +------------->o TCP port [R]

$ ssh -L L:remote2:R remote1

     local2   local1 ssh connection  remote
                    o------------->o
                     +------------+
                     v            ^
TCP port [L] o<------+            +<-o TCP port [R]
$ ssh -R R:local2:L remote

How to get absolute path

$ man realpath



    char *relativePath = "relativePath/file.txt"
    char *absolutePath = realpath(relativePath, NULL);
    if (!absolutePath)
    {
      stc::cerr << "Cannot access " << relativePath << ": No such file or directory";
      return -1;
    }
    // use it
    free(absolutePath);

How to make screenshot in MacOS X

http://www.imore.com/how-take-screenshot-mac-os-x

Command + Shift + 3 whole screen
Command + Shift + 4 area

How to find current executable’s path

#include <unistd.h>
#ifdef __APPLE__
#include <mach-o/dyld.h>
#endif

#ifndef __APPLE__
std::string getExecutableName()
{
    char buf[MAXPATHLEN];
    ssize_t len;
    if ((len = readlink("/proc/self/exe", buf, sizeof(buf) - 1)) != -1)
        buf[len] = '\0';
    return buf;
}
#else
std::string getExecutableName()
{
    char exe[MAXPATHLEN];
    uint32_t bufSize = sizeof(exe);
    _NSGetExecutablePath(exe, &bufSize);
    char buf[MAXPATHLEN];
    ssize_t len;
    if ((len = readlink(exe, buf, sizeof(buf) - 1)) != -1)
        buf[len] = '\0';
    return buf;
}
#endif

Remove duplicates from container without sorting the container

#include <algorithm>
#include <vector>
struct target_less
{
    template<class It>
    bool operator()(It const &a, It const &b) const { return *a < *b; }
};
struct target_equal
{
    template<class It>
    bool operator()(It const &a, It const &b) const { return *a == *b; }
};
template<class It> It uniquify(It begin, It const end)
{
    std::vector<It> v;
    v.reserve(static_cast<size_t>(std::distance(begin, end)));
    for (It i = begin; i != end; ++i)
    { v.push_back(i); }
    std::sort(v.begin(), v.end(), target_less());
    v.erase(std::unique(v.begin(), v.end(), target_equal()), v.end());
    std::sort(v.begin(), v.end());
    size_t j = 0;
    for (It i = begin; i != end && j != v.size(); ++i)
    {
        if (i == v[j])
        {
            using std::iter_swap; iter_swap(i, begin);
            ++j;
            ++begin;
        }
    }
    return begin;
}

Remove duplicates from container

sort( vec.begin(), vec.end() );
vec.erase( unique( vec.begin(), vec.end() ), vec.end() );

Load file into string

std::ifstream t("file.txt");
std::stringstream buffer;
buffer << t.rdbuf();

copy file

std::ifstream  src("from.ogv", std::ios::binary);
std::ofstream  dst("to.ogv",   std::ios::binary);
dst << src.rdbuf();

string low case

#include <algorithm>
#include <string> 

std::string data = "Abc"; 
std::transform(data.begin(), data.end(), data.begin(), ::tolower);

list of files in a directory

DIR *dir;
struct dirent *ent;
if ((dir = opendir ("c:\\src\\")) != NULL) {
  /* print all the files and directories within directory */
  while ((ent = readdir (dir)) != NULL) {
    printf ("%s\n", ent->d_name);
  }
  closedir (dir);
} else {
  /* could not open directory */
  perror ("");
  return EXIT_FAILURE;
}

http://stackoverflow.com/questions/612097/how-can-i-get-a-list-of-files-in-a-directory-using-c-or-c

C++ Erase vector element by value rather than by position?

vec.erase(std::remove(vec.begin(), vec.end(), 8), vec.end());

How to get my ip address in c Linux -…

getifaddrs(&addrs);
tmp = addrs;

while (tmp) 
{
    if (tmp->ifa_addr && tmp->ifa_addr->sa_family == AF_INET)
    {
        struct sockaddr_in *pAddr = (struct sockaddr_in *)tmp->ifa_addr;
        printf("%s: %s\n", tmp->ifa_name, inet_ntoa(pAddr->sin_addr));
    }

    tmp = tmp->ifa_next;
}

freeifaddrs(addrs);

How do I get the directory that a program is running from?

#include <stdio.h>  /* defines FILENAME_MAX */
#ifdef WINDOWS
    #include <direct.h>
    #define GetCurrentDir _getcwd
#else
    #include <unistd.h>
    #define GetCurrentDir getcwd
 #endif

 char cCurrentPath[FILENAME_MAX];

 if (!GetCurrentDir(cCurrentPath, sizeof(cCurrentPath)))
     {
     return errno;
     }

cCurrentPath[sizeof(cCurrentPath) - 1] = '\0'; /* not really required */

printf ("The current working directory is %s", cCurrentPath);

Windows:

int bytes = GetModuleFileName(NULL, pBuf, len);
if(bytes == 0)
    return -1;
else
    return bytes;

Linux:

char szTmp[32];
sprintf(szTmp, "/proc/%d/exe", getpid());
int bytes = MIN(readlink(szTmp, pBuf, len), len - 1);
if(bytes >= 0)
    pBuf[bytes] = '\0';
return bytes;

Converting YUV into BGR or RGB

for(int i = 0, j=0; i < 1280 * 720 * 3; i+=6, j+=4)
{
    m_RGB->imageData[i] = pData[j] + pData[j+3]*((1 - 0.299)/0.615);
    m_RGB->imageData[i+1] = pData[j] - pData[j+1]*((0.114*(1-0.114))/(0.436*0.587)) - pData[j+3]*((0.299*(1 - 0.299))/(0.615*0.587));
    m_RGB->imageData[i+2] = pData[j] + pData[j+1]*((1 - 0.114)/0.436);
    m_RGB->imageData[i+3] = pData[j+2] + pData[j+3]*((1 - 0.299)/0.615);
    m_RGB->imageData[i+4] = pData[j+2] - pData[j+1]*((0.114*(1-0.114))/(0.436*0.587)) - pData[j+3]*((0.299*(1 - 0.299))/(0.615*0.587));
    m_RGB->imageData[i+5] = pData[j+2] + pData[j+1]*((1 - 0.114)/0.436);
}

Convert time_t to string with format YYYY-MM-DD HH:MM:SS

char buff[20];
time_t now = time(NULL);
strftime(buff, 20, "%Y-%m-%d %H:%M:%S", localtime(&now));

How to convert a string variable containing time to time_t type in c++?

const char *time_details = "16:35:12";
struct tm tm;
strptime(time_details, "%H:%M:%S", &tm);
time_t t = mktime(&tm);  // t is now your desired time_t

Path to binary in C

#include <stdio.h>
#include <unistd.h>

int main()
{
  char buffer[BUFSIZ];
  readlink("/proc/self/exe", buffer, BUFSIZ);
  printf("%s\n", buffer);
}



WCHAR path[MAX_PATH];
GetModuleFileName(NULL, path, ARRAYSIZE(path));

Rotate screen

xrandr --output HDMI-0 --rotate left

Set wacom pen on one screeen

xsetwacom set "Wacom Bamboo 16FG 4x5 Pen stylus" MapToOutput HEAD-0

Run Minecraft

java -Xmx1024M -Xms512M -cp minecraft.jar net.minecraft.LauncherFrame

Set keyboard repeat rate

xset r rate 210 120

NATO phonetic alphabet

A ..........    ALPHA       N ..........    NOVEMBER
B ..........    BRAVO       O ..........    OSCAR
C ..........    CHARLIE     P ..........    PAPA
D ..........    DELTA       Q ..........    QUEBEC
E ..........    ECHO        R ..........    ROMEO
F ..........    FOXTROT     S ..........    SIERRA
G ..........    GOLF        T ..........    TANGO
H ..........    HOTEL       U ..........    UNIFORM
I ..........    INDIA       V ..........    VICTOR
J ..........    JULIET      W ..........    WHISKY
K ..........    KILO        X ..........    X-RAY
L ..........    LIMA        Y ..........    YANKEE
M ..........    MIKE        Z ..........    ZULU

Generate etags for emacs

find . -name "*.cpp" -print0 -or -name "*.c" -print0 -or -name "*.h" -print0 -or -name "*.c" -print0 | xargs -0 etags --append

valgrind

$ /usr/bin/valgrind --tool=memcheck --leak-check=yes --leak-check=full -v --show-reachable=yes [command line]

unixtime conversions

$ date -d @1193144433
Tue Oct 23 15:00:33 CEST 2007


$ date -d @1193144433 "+%Y-%m-%d %T"
2007-10-23 15:00:33

$date --date="Sun Oct 21 9:00:00 PDT 2012" +%s
1350835200

= generate news from lenta.ru

wget http://lenta.ru/rss/ -O- 2> /dev/null | grep http://.*news | sed 's/<link>//g' | sed 's/<.link>/_Printed.htm/g' | wget -i- -O- | grep -v -E '<.?html>' | grep -v -E '<.?title>' | grep -v -E '<!DOCTYPE' | htmldoc - -f "news`date +%Y-%m-%d`.pdf" -t pdf14 --webpage --right 1in --fontsize 10 

Run Minecraft

$ java -Xmx1024M -Xms512M -cp minecraft.jar net.minecraft.LauncherFrame

Gentoo related

emacs startup is slow

add line to /etc/hosts

127.0.0.1 cassiopeia

kernel select

eselect kernel list
eselect kernel set 3

grub updating

edit /boot/grub/grub.conf
mount /boot

kernel build

# cd /usr/src/linux
# make menuconfig
##copy .config file if needed from previus kernel
# cp ../linux.../.config .
# make && make modules_install
## if needed mount /boot partition
# mount /boot
# cp arch/x86_64/boot/bzImage /boot/kernel-2.6.36-gentoo-r5 
# module-rebuild rebuild

mount dvd

# mount -t iso9660 /dev/cdrom /dev/cdrom

play dvd

$ mplayer dvd://1

how to create tab.bz2

compress:

$ tar -jcvf archive_name.tar.bz2 directory_to_compress

extract:

$ tar -jxvf archive_name.tar.bz2 -C /tmp/extract_here/

update your system

# emerge --sync
# emerge --update --deep --ask world

update etc files

# etc-update


sleep 1; xset s activate

Удаление ненужных зависимостей

emerge --update --deep --newuse world && emerge --depclean && revdep-rebuild

Удаление пакета

sudo emerge -av --depclean transcode



ffmpeg -i c++_lessons38_speedup.ogv  -i audio.wav  -map 0:0 -map 1:0 -vcodec copy -av 320k c++_lessons38_audio.ogv 


mplayer dvd://1



sda5 boot
sda6 root

linux-2.6.36-gentoo-r5

GeForce GT420

rip dvd

mplayer dvd://1 -dumpstream -dumpfile rippeddvd.vob

Printing howto

http://www.gentoo.org/doc/en/printing-howto.xml

Add a existing user to existing group

usermod -a -G ftp tony

qfile codegen.py - найти файл

python-updater - обновить пакеты зависящие от питона

portageq owners / /usr/lib64/libeggdbus-1.so - найти пакет владельца файла

Синхронизировать время

sudo rdate -s ptbtime1.ptb.de

SSH login without password

Your aim

You want to use Linux and OpenSSH to automize your tasks. Therefore you need an automatic login from host A / user a to Host B / user b. You don’t want to enter any passwords, because you want to call ssh from a within a shell script.

How to do it

First log in on A as user a and generate a pair of authentication keys. Do not enter a passphrase:

a@A:~> ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/a/.ssh/id_rsa): 
Created directory '/home/a/.ssh'.
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/a/.ssh/id_rsa.
Your public key has been saved in /home/a/.ssh/id_rsa.pub.
The key fingerprint is:
3e:4f:05:79:3a:9f:96:7c:3b:ad:e9:58:37:bc:37:e4 a@A

Now use ssh to create a directory ~/.ssh as user b on B. (The directory may already exist, which is fine):

a@A:~> ssh b@B mkdir -p .ssh
b@B's password: 

Finally append a’s new public key to b@B:.ssh/authorized_keys and enter b’s password one last time:

a@A:~> cat .ssh/id_rsa.pub | ssh b@B 'cat >> .ssh/authorized_keys'
b@B's password: 

From now on you can log into B as b from A as a without password:

a@A:~> ssh b@B hostname

B A note from one of our readers: Depending on your version of SSH you might also have to do the following changes:

Put the public key in .ssh/authorized_keys2 Change the permissions of .ssh to 700 Change the permissions of .ssh/authorized_keys2 to 640

``` 13:50 03.02.03

Удаление писем из почтовой очереди sendmail

В каталоге /var/spool/mqueue/ удалить файлы этого письма. Для того чтобы узнать, что в почтовой области надо воспользоваться коммандой mqilq. Источник: http://penguin.photon.ru/doc/mail/index.html

17:24 04.02.03

Разрешить отправку писем по IP

1) В файл /etc/mail/access включить строку: xxx.xxx.xxx.xxx RELAY где xxx.xxx.xxx.xxx требуемый IP адрес.

2) Дать команду: makemap hash /etc/mail/access.db < /etc/mail/access

Информацию по sendmail можно найти по адресу http://gyro.hotbox.ru/sendmail/index.html .

16:25 17.04.03

Процедура добавление нового пользователя

• получить права root
• добавить пользователя /usr/sbin/adduser -g ec -G ecsoft -d /home/public/upload/user user
• ввести пароль passwd user
• запретить доступ к серверу через терминал, поправив файл /etc/passwd
• добавить пользователя в SMB smbadduser user:user
• поменять права папки нового пользователя chmod 750 /home/public/upload/user

13:48 29.04.03

Перезапустить SMB сервер

1) получить права ROOT 2) /etc/rc.d/init.d/smb restart

20:29 17.06.03

Включить NAT

1) получить права root echo 1 > /proc/sys/net/ipv4/ip_forward /sbin/iptables -t nat -A POSTROUTING -s 192.168.0.0/16 –out-interface eth0 -j SNAT –to-source 194.67.66.38 /sbin/iptables-save > /etc/sysconfig/iptables echo 1 > /proc/sys/net/ipv4/ip_forward

вставить в файл /etc/rc.d/rc.local

Sendmail задумывается

/etc/hosts прописали 127.0.0.1 localhost 194.67.66.38 ecsoft ecsoft.mephi.ru 192.168.0.1 ecsoft

16:27 18.06.03

Запустить ftp

ln –symbolic /etc/init.d/vsftpd S50vsftpd

В vsftpd.conf редактируем следующие строки:

anonymous_enable=NO - если не хотим разрешать доступ для анонимных пользователей. local_enable=YES - чтобы разрешить доступ локальным пользователям системы. write_enable=YES - чтобы разрешить им запись. local_umask=022 - ставим более либеральную маску. chroot_list_enable=YES chroot_local_user=YES chroot_list_file=/usr/local/etc/vsftpd.chroot_list

последние три строки означают изменить корневую директорию на домашнюю для всех пользователей, кроме перечисленных (в столбик) в файле vsftpd.chroot_list . Например, если в файле vsftpd.chroot_list будут перечислены пользователи john и boris, то им будет доступна вся корневая дирректория (насколько им позволяют права, конечно), а остальные пользователи не смогут выйти за рамки своих домашних каталогов.

Это лишь один из примеров настройки этого сервера. Конфигурационный файл хорошо документирован, поэтому легко понять что к чему.

Добавили пользователя skib

/usr/sbin/groupadd ec

/usr/sbin/groupadd ecsoft

/usr/sbin/adduser -g ec -d /home/skib skib

passwd skib

chmod 750 /home/skib

Изменяем владельца группу у домашних папок

chown :ec alex

chown :ecsoft anton

chown :ec borya

chown :ecsoft dima

chown :ec fva

chown :ecsoft hunter

chown :ec lgau

chown :ec mav

chown :ec plugged

chown :ec rpt

chown :ec sasa

chown :ecsoft serge

chown :ecsoft sna

chmod 770 alex

chmod 770 anton

chmod 770 borya

chmod 770 dima

chmod 770 fva

chmod 770 hunter

chmod 770 lgau

chmod 770 mav

chmod 770 plugged

chmod 770 rpt

chmod 770 sasa

chmod 770 skib

chmod 770 sna

/usr/sbin/usermod -g ec -G ecsoft anton

/usr/sbin/usermod -g ec -G ecsoft dima

/usr/sbin/usermod -g ec -G ecsoft hunter

/usr/sbin/usermod -g ec -G ecsoft serge

/usr/sbin/usermod -g ec -G ecsoft sna

/usr/sbin/usermod -g ec alex

/usr/sbin/usermod -g ec borya

/usr/sbin/usermod -g ec fva

/usr/sbin/usermod -g ec lgau

/usr/sbin/usermod -g ec mav

/usr/sbin/usermod -g ec plugged

/usr/sbin/usermod -g ec rpt

/usr/sbin/usermod -g ec sasa

/usr/sbin/usermod -g ec skib

Настройка Самбы

Файл /etc/samba/smb.conf

workgroup = ECSOFTNET

server string = Powered ASP Linux 9

hosts allow = 192.168.0.

domain master = yes

domain logon = yes

interfaces = 192.168.0.1/24

character set = 1251 client code page = 866

[homes] comment = Home Directories browseable = no writable = yes valid users = %S create mode = 0660 directory mode = 0770

If you want users samba doesn’t recognize to be mapped to a guest user

; map to guest = bad user

[public] comment = Public Stuff path = /home/skib/ public = yes writable = yes printable = no write list = @ec create mode = 0661 directory mode = 2775

[lp0] security = server path = /var/spool/lpd/lp printer name = lj1200 writable = yes public = yes printable = yes print command = lpr -r -h -P %p %s

Добавить в автозагрузку Самбу ln –symbolic /etc/rc.d/init.d/smb /etc/rc.d/rc3.d/S35smb

21:00 18.06.03 Добавили папку SOFT

/usr/sbin/usermod -G ec,softman anton

/usr/sbin/usermod -G ec,softman hunter

chown :softman SOFT

chmod 775 SOFT

13:58 19.06.03

Редирект на другой IP и на другой порт

/sbin/iptables -t nat -A PREROUTING -p TCP -d 194.67.66.38 –dport 4665 -j DNAT –to-destination 192.168.0.9

15:26 20.06.03

Настройка принтера через Samba

• Установить пакет redhat-config-printer и все зависимые от него пакеты.

• printconf

• и дабавляется принтер с такими параметрами Имя: lj1200 Доп. имена: Тип: Устройство локального принтера: Устройство принтера: /dev/lp0 Драйвер: HP LaserJet 1200 using Postscript driver

17:50 24.06.03

Настройка dhcpd

• Создать файл /etc/dhcpd.conf

ddns-update-style interim; subnet 192.168.0.0 netmask 255.255.255.0 {

— default gateway

    option routers                  192.168.0.1;
    option subnet-mask              255.255.255.0;

    option domain-name      "ecsoft.mephi.ru";
    option domain-name-servers      194.67.67.34, 194.67.67.130;

    range 192.168.0.2 192.168.0.100;
    default-lease-time 21600;
    max-lease-time 43200;

}

• Запустить демона

  /etc/rc.d/init.d/dhcpd start

• Записать в автозагрузку ln –symbolic /etc/rc.d/init.d/dhcpd /etc/rc.d/rc3.d/S35dhcpd 15:44 30.06.03

  Добавили ползователя

/usr/sbin/adduser -g ec -G ecsoft -d /home/alexakov alexakov

passwd alexakov

; подправили группу

/usr/sbin/usermod -g ec alexakov

16:36 09.07.03

Добавить новый алиас

• Поправить файл /etc/aliases
• дать команду newaliases

15:05 19.04.04

Поменять местами сетевухи

• исправить файлы /etc/sysconfig/network-scripts/ifcfg-eth0 /etc/sysconfig/network-scripts/ifcfg-eth1

18:21 19.04.04

Прописать шлюз по умолчанию

в файле /etc/sysconfig/network-scripts/ifcfg-eth1 должно быть написано: DEVICE=eth1 ONBOOT=yes IPADDR=194.67.66.38 NETMASK=255.255.255.0 NETWORK=194.67.66.0 BROADCAST=194.67.66.255 GATEWAY=194.67.66.130 19:26 18.08.04

Инициализация SWAP

/sbin/mkswap /dev/hda5 14:20 19.12.2005

Кодировка в SAMBA

в файле /etc/samba/smb.conf в разделе [global] добавить две строчки

unix charset = windows-1251 dos charset = cp866

14:51 17.07.2006

После перезагрузки сервера выполнить

mount /dev/hda6 /home

cd /home/hunter/Templates/ ./firewall1.sh /etc/init.d/vsftpd start /etc/init.d/dovecot start /etc/init.d/httpd start

Для emule /sbin/iptables -t nat -A PREROUTING -p TCP -i eth0 -d 194.67.66.38 –dport 4665 -j DNAT –to-destination 192.168.0.9

wrUL30pq 18:23 02.11.2006 antivir -s -z –heur-macro –heur-level=4 -v / 18:19 08.12.2006

очистка почтового ящика

• Запустить mail -u user
• набрать s * old_mail.txt
• q выход

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