Linux, Embedded Systems, Networking, and DevOps Engineering

Python

Items Details
Open/write/close/ a file
 
# check file is exists
os.path.isfile("config.json")

# Open for reading
fh = open(configFile, "r")
data = fh.read()

# Open for writing
file = open("config.json", "w")
file.write(json.dumps(json_object, indent=4, sort_keys=True))
file.flush()
file.close()
Atexit
 
import atexit

@atexit.register
def goodbye():
    print('You are now leaving the Python sector.')
AppOpps
 
from optparse import OptionParser

def parseOpt(self, args):
    usage = "usage: %prog [options] arg"
    parser = OptionParser(usage)
    parser.add_option("-t", "--test", action="store", type="string", dest="test",help="Test store string")
    parser.add_option("--bool",action="store_const", const=1, dest="bool",help="Test store bool")
    parser.add_option("--value", action="store", type="int", dest="value",help="common value for other command")

    (options, args) = parser.parse_args(args)
    if len(args) != 1:
        parser.error("incorrect number of arguments")
    if options.bool:
        print(options.bool)
    if options.value:
        print("value = ", options.value)
    if options.test:
        print("test = ", options.test)

if __name__ == "__main__":
    parseOpt(sys.argv)
json
 
# load from string data
j_obj = json.loads(str_data)

# Level 1 keys
for key in j_obj.keys():
    print(f"key {key}, data: {j_obj[key]}")
Regular Expression
 
import re
string = "hello MY_PC_NAME , value: 1.34"

# match name and value
pattern = 'hello (\D+) , value: (\d+.\d+)'
match = re.search(pattern, string)
if match:
    print(f'str: {match.group(1)}, value: {match.group(2)}')
subprocess
 
import subprocess

def system_call(command):
    return str(subprocess.getoutput(command))
Natural Sort
 
from natsort import natsorted

list = ["1", "10", "2", "22", "3", "55"]
print(natsorted(list)) # 1,2,3,10,22,55
Play beep audio
 
import beepy as beep

beep.beep(1)
beep.beep(2)
...
beep.beep(10)
trim string white space
 
str("   hello    ").strip()
Date and time
 
from datetime import datetime, date

datetime.utcnow()
datetime.utcnow().hour
datetime.utcnow().minute
datetime.utcnow().second
datetime.utcnow().timetuple().tm_yday // day of year
datetime.utcnow().timetuple().tm_year
datetime.utcnow().timetuple().tm_mon
datetime.utcnow().timetuple().tm_mday
datetime.utcnow().timetuple().tm_hour
datetime.utcnow().timetuple().tm_min
datetime.utcnow().timetuple().tm_sec
datetime.utcnow().timetuple().tm_wday
import calendar
today = date.today()
weekday = today.weekday()
day_name = calendar.day_name[today.weekday()]
current_day = today.strftime("%b-%d-%Y")
current_day_object = datetime.strptime(current_day, '%b-%d-%Y')
current_day_utc = current_day_object.utcnow().strftime("%b-%d-%Y")