Linux root password reset

Mode 1:Recover mode

In recover mode try to remount and after that change password

mount -o remount,rw /
 
Mode 2: Using live

mkdir /mnt/recover
mount /dev/sda2 /mnt/recover
 
chroot /mnt/recover
 
passwd  #or
passwd user 
exit
umount /mnt/recover

Other way : Using files(for root or any user)
 
 /etc/passwd
 /etc/shadow
  
root:x:0:0:root:/root:/bin/bash
to
root::0:0:root:/root:/bin/bash 

References:

[1] http://www.microhowto.info/howto/reset_a_forgotten_root_password_using_a_live_distribution.html

[2] https://www.computersecuritystudent.com/UNIX/UBUNTU/1204/lesson5/index.html

Epson Drivers

Resources:
[1]  https://goo.gl/4vrWdC

Raspberry Resources

DOSBox and rpi-x86 will play DOS games and run Win31/Win95.

QEMU can be used to emulate an x86 PC but performance will be terrible.

Wine will not work because it does not translate binary data, only Windows API calls, the binaries are still incompatible.

This is a difficult problem to solve which is probably why ExaGear charge money for it.

Resources:
[1] Chart comparison all famous Arm processors https://www.loverpi.com/blogs/news/85588545-raspberry-pi-banana-pi-orange-pi-odroid-differences-and-chart
[2] Odroid vs other https://tudosobreraspberry.info/2017/08/comparacao-raspberry-pi-orange-pi-banana-pi-e-odroid/

[3] Raspberry Pi3 vs UDOO x86 https://www.youtube.com/watch?v=dJkHxDjFuNA
[4] Combine qemu and wine for run Windows applications https://github.com/AlbrechtL/RPi-QEMU-x86-wine
[5] https://www.kickstarter.com/projects/udoo/udoo-x86-the-most-powerful-maker-board-ever/?src=soc
[6] https://www.raspberrypi.org/forums/viewtopic.php?t=189198

[7] https://elchapuzasinformatico.com/2016/04/udoo-x86-10-veces-mas-potente-raspberry-pi-3-79e/
[8] https://www.redeszone.net/2016/05/20/udoo-x86-mini-ordenador-10-veces-mas-potente-raspberry-pi-3/
[9] https://www.anandtech.com/show/11978/macom-sells-off-appliedmicros-xgene-cpu-business
[1] Experimental comparison Raspberry and Orange https://raspberryparatorpes.net/rivales/raspberry-pi-vs-orange-pi-2017/

Ubuntu users

#adduser username

#usermod -aG sudo username

$su - username

$whoami

$sudo whoami   

Examples to use

$fdisk -l

$sudo fdisk -l

$sudo ls -l /root



mySql Optimization parameters or commands

Query

SHOW GLOBAL STATUS

SHOW VARIABLES LIKE '%size%';
SHOW GLOBAL VARIABLES LIKE '%size%';

Settings

SET GLOBAL join_buffer_size = 1024 * 1024 * 128 #128M

or

[mysqld]
join_buffer_size = 128M  #default ~256K

 

References:

[0] Compute memory http://mysqlcalculator.com/ 

[1] join_buffer_size https://dba.stackexchange.com/questions/74693/how-to-break-table-into-two-without-losing-performance 

[2] https://dev.mysql.com/doc/refman/8.0/en/server-system-variables.html

[3] Example tunning https://dba.stackexchange.com/questions/127862/tuning-mysql-variables-to-accommodate-high-load

[4] Query variables https://dev.mysql.com/doc/refman/8.0/en/show-variables.html

Sunat Servicios Web

Resources:
[1] Code perl http://cpan.dei.uc.pt/authors/id/G/GP/GPAREDES/SUNAT/SEE.pm

[2] http://orientacion.sunat.gob.pe/index.php/empresas-menu/comprobantes-de-pago-empresas/comprobantes-de-pago-electronicos-empresas/see-desde-los-sistemas-del-contribuyente/guias-manuales-y-servicios-web

JavaScript Frameworks Lecture

References:

[1] https://reactjs.org/
[2] https://www.w3schools.com/whatis/whatis_react.asp
[3] Repository https://github.com/facebook/react

mySql Common Commands

CREATE TABLE foo LIKE bar;

CREATE TABLE IF NOT EXISTS offices_bk

SELECT * FROM

    offices;

==

CREATE TABLE IF NOT EXISTS new_table LIKE existing_table;

INSERT new_table

SELECT * FROM existing_table;

ALTER TABLE <tablename> CHANGE COLUMN <colname> <colname> VARCHAR(65536);

ALTER TABLE emp MODIFY COLUMN name VARCHAR(100);

Or use CHANGE, but that means you have to give the column name twice (because CHANGE allows you to change the name of the column too).
ALTER TABLE emp CHANGE COLUMN name name VARCHAR(100);

Linux Discover Teamviewer id

$sudo grep -n id /home/user/.local/share/teamviewer14/logfiles/TeamViewer14_Logfile.log

$whereis teamviewer
$/usr/bin/teamviewer help
$/usr/bin/teamviewer info #for get id too

$/usr/bin/teamviewer daemon stop
$/usr/bin/teamviewer setup
$/usr/bin/teamviewer daemon status
$/usr/bin/teamviewer daemon start

References:
[1] http://www.tonisoto.com/2013/07/launching-teamviewer-remotely-throught-ssh/

mySql change port problem

Can't start server: Bind on TCP/IP port: Permission denied
Do you already have another mysqld server running on port: 13306 ?


Common solution is change my.cnf adding port=newport, but in what section?

Discover who is the principal executable
$locate mysqld.service

/etc/systemd/system/multi-user.target.wants/mysqld.service
/usr/lib/systemd/system/mysqld.service

$vi /usr/lib/systemd/system/mysqld.service #for watch settings
In my case, was this:
ExecStart=/usr/bin/mysqld_safe --basedir=/usr

then i know what section i need to change

$vi /etc/my.cnf  # add new port in section [mysqld_safe]

Aditional commands during process:

tail -30 /var/log/mysql/error.log

sudo lsof -i TCP:3306
netstat -lp | grep 3306
 

$systemctl status iptables.service

$service iptables status

Ubuntu mySQL Backup/Restore

1)Create


2) Restore


$mysql -u root -p mysql
> create database mydb; mysql
> use mydb; mysql
> source db_backup.dump;


3) Another way, you  need to run:

$mysql -p -u[user] [database] < db_backup.dump

If the dump contains multiple databases you should omit the database name:

$mysql -p -u[user] < db_backup.dump

4) Restore specific database

$mysql -u onepoint -p --one-database maxx2016 < back_20190226.sql