CQNET

Compilation of tips, notes, and useful commands for setting up and running the code from CQNET.

General Comments

• If the code doesn't run or asks for permission, you may need to run the script as root.

Github

Useful commands

• Check status of local repo: git status
• Switch branch: git checkout <branch>
• Store local changes: git stash
• Download files from branch called of github repo: git pull origin <branch>
• Add everything from local repo: git add .
• Commit with message <...>: git commit -m <...>
• Add + commit with message <...>: git commit -a -m "<...>"
• Upload commits from local repo to github repo: git push

Tips

• If you forgot to pull before making local changes, you can save local changes, pull, then revert to local changes by doing:

   git stash
   git pull origin <branch>
   git stash pop
  

• Suggested order of commands to push local repo to github repo:

   git status
   git checkout <branch> //if necessary
   git stash //to be safe
   git pull //makes local repo same as github repo
   git stash pop //updates the pulled repo with stashed changes
   git add .
   git commit -m "<Explanation of changes>"
   git push
  

• If you get something like warning: LF will be replaced by CRLF in <filename>. in the terminal, it's due to incompatible end of line specifications from different OS e.g. if uploaded code run on Linux from a Windows computer or vice versa.

  • Unix: End of line represented with line feed (LF)
    • When you get code from git that was uploaded from a unix system they will only have an LF
    • Command to tell git to convert LF endings into CRLF when you checkout code: git config --global core.autocrlf true
  • Windows: End of line represented with carriage return (CR) and a line feed (LF) thus (CRLF)
    • When upload from windows, converts LF to CRLF
    • Command to tell git to convert CRLF to LF on commit, but not the other way around: git config --global core.autocrlf input

Python

Useful commands

Linux

• To install python 3.6 on CentOS7: https://linuxhint.com/install_python3_centos7/

• To install python 3.7 on CentOS7: https://tecadmin.net/install-python-3-7-on-centos/

• To install python 3.8 on CentOS7: https://tecadmin.net/install-python-3-8-centos/

• To change default version of python: alias python3=$(which python3.x) where "python3.x" is the version you want as default

  • Now when type python3 in terminal will get "python3.x" to run

• To install python packages on Linux terminal, use:

  • python -m pip install --user <package1> <package2> ...
  • python3 -m pip install --user <package1> <package2> ...
  • sudo yum install <package>

• To build python software on RHEL terminal:

   cd /usr/src/Python-3.7.3
   ./configure --enable optimizations
   make altinstall
  

Windows

• To run different versions of python on Windows cmd, use:

  • py -2 (python2)
  • py -3 (python3)

• To install python packages on Windows, use:

  • py -3 -m pip install <package name> (python3)

Tips

• If you are on Centos 7, install tkinter to use graphical interface for viewing matplotlib plots: sudo yum install python3-tkinter
• For plotting, use this to adjust spacing between subplots: matplotlib.pyplot.subplots_adjust(left=None, bottom=None, right=None, top=None, wspace=None, hspace=None)
  • left = 0.125 (the left side of the subplots of the figure)
  • right = 0.9 (the right side of the subplots of the figure)
  • bottom = 0.1 (the bottom of the subplots of the figure)
  • top = 0.9 (the top of the subplots of the figure)
  • wspace = 0.2 (the amount of width reserved for space between subplots, expressed as a fraction of the averge axis width)
  • hspace = 0.2 (the amount of height reserved for space between subplots, expressed as a fraction of the average axis height)

Mysql

To install mysql: https://www.hostinger.com/tutorials/how-to-install-mysql-on-centos-7

Useful commands

Angle bracket terms should be replaced with your inputs.

Login to mysql

These commands will prompt for password.

• From computer with database:

mysql -u root -p

• From computer in network:

mysql -u <username> -h '<IP address>' -p

Create database

create database <database name>;

Create user

create user '<username>'@'<IP address>'
	identified by '<password>';

grant all on *.*
	to '<username>'@'<IP address>'  
	with grant option;

• On terminal of computer with database:

grant all privileges on *.* to '<username>'@'<IP address>' with grant option;
flush privileges;

For more info, look up "MySQL 6.2.8 Adding Accounts, Assigning Privileges, and Dropping Accounts"

Drop user

drop user '<username>'@'<IP address>'

Create table

Example: create table called myTable with five columns and different datatypes.

create table myTable(id int not null primary key auto_increment,
                         Vmax0 float,
                         Vmax1 float,
                         Vmax2 float,
                         datetime datetime); //create a new table

Select single row of table

Example:

select *
from <table name>
where <primary key name> = 123;

Select multiple rows of table

Example:

select * from <table name> limit 55719,76063;

Rename table

ALTER TABLE <old_table> RENAME <new_table>;

Rename column of table

alter table <table name> rename column <old name> to <new name>;

Add column

ALTER TABLE table ADD [COLUMN] <column_name_1> <column_1_definition> [FIRST|AFTER existing_column];

The square bracket terms are optional.

Other

SCP

• To transfer files over computers in network using Linux terminal: scp -r ./<filename> <username>@<ip address>:<folder path>

Serial

• To check the serial ports in Linux terminal: python3 -m serial.tools.list_ports