Currently reading articles under label: backend-server-linux

Scala the Language

Install Sbt

echo "deb /" | sudo tee -a /etc/apt/sources.list.d/sbt.list

sudo apt-key adv --keyserver hkp:// --recv 2EE0EA64E40A89B84B2DF73499E82A75642AC823

sudo apt-get update

sudo apt-get install sbt

ref: (v1.0)



Install Single-Node for Test


# server

curl -LO && sudo install minikube-linux-amd64 /usr/local/bin/minikube

minikube start

# client

sudo apt-get update && sudo apt-get install -y apt-transport-https &......

GRUB Rescue

When being forced into GRUB rescue mode, run ls and ls <one_partition> to check available partitions and find the one that we should boot from [ref].

Then set prefix & root[ref]:

set root=(hdX,Y)

set prefix=(hdX,Y)/boot/grub

insmod n......

Python Code Cookbook

See also:

Learning Python, the Language


Get column_nr in pandas/numpy.

if isinstance(X, pd.DataFrame):

X_is_df = True

row_nr = X.shape[0]

column_nr = X.shape[1]

if isinstance(X.columns, pd.core.index.MultiIndex):

df_columns_is_multi_index = True



Steps to Check Netwok Interface Card (NIC) Configurations

Check the physical NIC is connected.


Note: The NIC will be shown regardless if drivers are installed, this is a PCI feature. Ref.

Then check if it is recognized as network interfaces:

ifconfig -a

Check if it is up:




apt-get install quota


Add options usrquota,grpquota in /etc/fstab:

UUID=a5bcc8d7-asdf / ext4 errors=remount-ro,usrquota,grpquota 0 1

Set quota:

setquota -u -F vfsv0 USERNAME 4000000 5000000 0 0 /

4 000 000 ≈ 4GB.

OBS: block size is always 1 KB as unit, regardless file ......