README

Repo name: random_hostname_nick3499 Set system hostname with pseudo-random alpha-numeric string.

Note: random_hostname.py changes system hostname; be sure user wants system hostname to change.

Shebang/Interpreter Directive

The shebang line starts with #!, because those human-readable characters, encoded to ASCII, become 0x23 and 0x21, which together become a magic number or a magic byte string detected by functions in the exec() family. Such exec() functions ascertain whether a file is an executable binary or a script.

Note: the space between the shebang and the interpreter directive is optional.

Import Modules

from random import randrange
from subprocess import run

• random.randrange() returns a random integer within a specific range.
• subprocess.run() executes Bash command described by args from Python.

subprocess.run()

After the script is done juggling and playing slight of hand with characters, rand_host is passed as an arg to hostnamectl through the subprocess.run() method.

run(['sudo', 'hostnamectl', 'set-hostname', rand_host], check=True)

• subprocess.run() runs hostnamectl in Bash, waits for hostnamectl to finish, then returns a CompletedProcess instance.
• check=True captures stdout or stderr.

random.randrange()

random.randrange() returns a peudo-random number. psuedo-random, basically, because random logic is an oxymoron. random.randrange() takes three integers: random.randrange(start, stop, increment). The integer returned becomes a Unicode code point passed to the chr() built-in method, where chr(97) returns 'a', so chr(randrange(97, 123, 1)) will return a pseudo-random lowercase letter between 'a' and 'z', just as the f-string f'{rand_lwr()}' returns a lowercase letter.

rand_host

An f-string is assigned to rand_host. Each set of braces contains an embedded expression. For example, the f-string f'{rand_az()}' could become 'q', since rand_az() returns a random lowercase letter.

rand_host = f'{rand_az()}{rand_AZ()}{rand_09()}{rand_az()}{rand_AZ()}{rand_09()}'

rand_host would contain something akin to mV4jA8, as each embedded expression returns a character. See Example Prompt section.

Example Prompt

foo@sA1nJ5:~/Desktop $