AWS

Discover instance ID using wget or curl:

wget -q -O - http://169.254.169.254/latest/meta-data/instance-id
curl http://169.254.169.254/latest/meta-data/instance-id

Excel

Get the number of occurrences of a text on a given string

Considering cell G4 is the target:

=(LEN(G4)-LEN(SUBSTITUTE(G4;"search";"")))/LEN("search")

MySQL

Generating an UUID4 using query:

SELECT LOWER(CONCAT(
    LPAD(HEX(FLOOR(RAND() * 0xffff)), 4, '0'),
    LPAD(HEX(FLOOR(RAND() * 0xffff)), 4, '0'), '-',
    LPAD(HEX(FLOOR(RAND() * 0xffff)), 4, '0'), '-',
    '4',
    LPAD(HEX(FLOOR(RAND() * 0x0fff)), 3, '0'), '-',
    HEX(FLOOR(RAND() * 4 + 8)),
    LPAD(HEX(FLOOR(RAND() * 0x0fff)), 3, '0'), '-',
    LPAD(HEX(FLOOR(RAND() * 0xffff)), 4, '0'),
    LPAD(HEX(FLOOR(RAND() * 0xffff)), 4, '0'),
    LPAD(HEX(FLOOR(RAND() * 0xffff)), 4, '0')))

PostgreSQL

User administration

\c postgres;
CREATE USER "full.name" WITH PASSWORD 'letmein';
ALTER ROLE "full.name" WITH LOGIN;
GRANT bi_users TO "full.name";
GRANT "outro.user" TO "full.name";

Kubernetes

Secrets

Update a secret

kubectl create secret generic production-tls \
    --from-file=./tls.key --from-file=./tls.crt --dry-run -o yaml | \
    kubectl apply -f -

Python

Files

Check if a file exists:

import os.path
os.path.isfile(fname)

Arrays

arr = [1,2,3]

# Add elements
arr.append(4)
arr.append(4)

# Get the number of unique elements
uniques = set(arr)

Objects

Python copies object by reference. Use copy() if you need a local copy:

oldDict = {"a": False}
newDict = oldDict.copy()
newdict["a"] = True

Dictionaries

Get and remove an element from the dictionary:

d = {'a': 10, 'b': 20, 'c': 30}
d.pop('b') #20
d # {'a': 10, 'c': 30}

Strings

Substrings:

string = "Hello"
string[:2] # 'He'
string[2:] # 'llo'
string[-1:] # 'o'

PIP

Create a requirements.txt file:

pip freeze > requirements.txt