仅需5道题轻松掌握Python命令行相关标准库 | Python技能树征题
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仅需5道题轻松掌握Python命令行相关标准库 | Python技能树征题
0. 前言
许多用户习惯于使用命令行工具与系统进行交互，因此 Python 中的提供了相应的标准库，用于向通过 shell 和文本与用户进行交互的软件提供常见方法和函数，我们就通过 5 道 Python 编程题来掌握 Python 相关标准库玩转命令行！
1. 第 1 题：命令行日志记录
知识点描述：使用 Python logging 模块记录运行信息。
问题描述：默认情况下 logging 模块只会输出错误信息，如何使 logging 记录程序运行中包括警告等更普通的运行信息，请从以下选项中选出你认为正确的答案：
A.
import logging, sys
logging.basicConfig(level=logging.INFO, stream=sys.stderr, format='%(asctime)s %(name)s %(levelname)s %(message)s')
log = logging.getLogger(__name__)
def my_add(a, b, weight=1):
log.info('Starting add')
if a == b == 0:
log.warning('Warning! 0 for any one')
res = (a + b) * weight
log.info('(%s + %s) * %s = %s' % (a, b, weight, res))
print(res)
if __name__ == '__main__':
my_add(5, 3)
my_add(0, 0)
B.
import logging, sys
logging.basicConfig(level=logging.ERROR, stream=sys.stderr, format='%(asctime)s %(name)s %(levelname)s %(message)s')
log = logging.getLogger(__name__)
def my_add(a, b, weight=1):
log.info('Starting add')
if a == b == 0:
log.warning('Warning! 0 for any one')
res = (a + b) * weight
log.info('(%s + %s) * %s = %s' % (a, b, weight, res))
print(res)
if __name__ == '__main__':
my_add(5, 3)
my_add(0, 0)
C.
import logging, sys
logging.basicConfig(level=logging.NOTSET, stream=sys.stderr, format='%(asctime)s %(name)s %(levelname)s %(message)s')
log = logging.getLogger(__name__)
def my_add(a, b, weight=1):
log.info('Starting add')
if a == b == 0:
log.warning('Warning! 0 for any one')
res = (a + b) * weight
log.info('(%s + %s) * %s = %s' % (a, b, weight, res))
print(res)
if __name__ == '__main__':
my_add(5, 3)
my_add(0, 0)
D.
import logging, sys
logging.basicConfig(level=logging.WARN, stream=sys.stderr, format='%(asctime)s %(name)s %(levelname)s %(message)s')
log = logging.getLogger(__name__)
def my_add(a, b, weight=1):
log.info('Starting add')
if a == b == 0:
log.warning('Warning! 0 for any one')
res = (a + b) * weight
log.info('(%s + %s) * %s = %s' % (a, b, weight, res))
print(res)
if __name__ == '__main__':
my_add(5, 3)
my_add(0, 0)
正确答案： A
2. 第 2 题：将日志存储在磁盘上
知识点描述：将日志信息写入磁盘文件中。
问题描述：编写斐波那契计算函数，并用日志文件记录计算出的数字以及运行时间，请从以下选项中选出你认为正确的答案：
A.
import logging, sys
import datetime
def f(n):
log.info('Computing up to %sth fibonacci number', n)
a, b = 0, 1
for n in range(n):
a, b = b, a+b
print(b, '', end='')
print(b)
logging_file = 'log.txt'
logging.basicConfig(level=logging.WARN, filename=logging_file, format='%(asctime)s %(name)s %(levelname)s: %(message)s')
log = logging.getLogger(__name__)
if __name__ == '__main__':
f(datetime.datetime.now().second)
B.
import logging, sys
import datetime
def f(n):
log.info('Computing up to %sth fibonacci number', n)
a, b = 0, 1
for n in range(n):
a, b = b, a+b
print(b, '', end='')
print(b)
logging_file = 'log.txt'
logging.basicConfig(level=logging.WARN, format='%(asctime)s %(name)s %(levelname)s: %(message)s')
log = logging.getLogger(__name__)
if __name__ == '__main__':
f(datetime.datetime.now().second)
C.
import logging, sys
import datetime
def f(n):
log.info('Computing up to %sth fibonacci number', n)
a, b = 0, 1
for n in range(n):
a, b = b, a+b
print(b, '', end='')
print(b)
logging_file = 'log.txt'
logging.basicConfig(level=logging.INFO, filename=logging_file, format='%(asctime)s %(name)s %(levelname)s: %(message)s')
log = logging.getLogger(__name__)
if __name__ == '__main__':
f(datetime.datetime.now().second)
D.
import logging, sys
import datetime
def f(n):
a, b = 0, 1
for n in range(n):
a, b = b, a+b
print(b, '', end='')
print(b)
logging_file = 'log.txt'
logging.basicConfig(level=logging.INFO, filename=logging_file, format='%(asctime)s %(name)s %(levelname)s: %(message)s')
log = logging.getLogger(__name__)
if __name__ == '__main__':
f(datetime.datetime.now().second)
正确答案： C
3. 第 3 题：命令行参数解析
知识点描述：编写命令行工具，根据提供给脚本的选项参数改变程序行为。
问题描述：编写命令行工具，根据提供给脚本的选项参数可以运行多个数据间的加/减/乘/除，请从以下选项中选出你认为正确的选项：
A.
import argparse
import operator
import logging
import functools
parser = argparse.ArgumentParser(description='Applies an operation to one or more numbers')
parser.add_argument("number", help="One or more numbers to perform an operation on.", type=int)
parser.add_argument('-o', '--operation', help="The operation to perform on numbers.", choices=['add', 'sub', 'mul', 'div'], default='add')
parser.add_argument("-v", "--verbose", action="store_true", help="increase output verbosity")
opts = parser.parse_args()
logging.basicConfig(level=logging.INFO if opts.verbose else logging.WARNING)
log = logging.getLogger()
operation = getattr(operator, opts.operation)
log.info('Applying %s to %s', opts.operation, opts.number)
print(functools.reduce(operation, opts.number))
B.
import argparse
import operator
import logging
import functools
parser = argparse.ArgumentParser(description='Applies an operation to one or more numbers')
parser.add_argument("number", help="One or more numbers to perform an operation on.", nargs='+')
parser.add_argument('-o', '--operation', help="The operation to perform on numbers.", choices=['add', 'sub', 'mul', 'div'], default='add')
parser.add_argument("-v", "--verbose", action="store_true", help="increase output verbosity")
opts = parser.parse_args()
logging.basicConfig(level=logging.INFO if opts.verbose else logging.WARNING)
log = logging.getLogger()
operation = getattr(operator, opts.operation)
log.info('Applying %s to %s', opts.operation, opts.number)
print(functools.reduce(operation, opts.number))
C.
import argparse
import operator
import logging
import functools
parser = argparse.ArgumentParser(description='Applies an operation to one or more numbers')
parser.add_argument("number", help="One or more numbers to perform an operation on.", nargs='2', type=int)
parser.add_argument('-o', '--operation', help="The operation to perform on numbers.", choices=['add', 'sub', 'mul', 'div'], default='add')
parser.add_argument("-v", "--verbose", action="store_true", help="increase output verbosity")
opts = parser.parse_args()
logging.basicConfig(level=logging.INFO if opts.verbose else logging.WARNING)
log = logging.getLogger()
operation = getattr(operator, opts.operation)
log.info('Applying %s to %s', opts.operation, opts.number)
print(functools.reduce(operation, opts.number))
D.
import argparse
import operator
import logging
import functools
parser = argparse.ArgumentParser(description='Applies an operation to one or more numbers')
parser.add_argument("number", help="One or more numbers to perform an operation on.", nargs='+', type=int)
parser.add_argument('-o', '--operation', help="The operation to perform on numbers.", choices=['add', 'sub', 'mul', 'div'], default='add')
parser.add_argument("-v", "--verbose", action="store_true", help="increase output verbosity")
opts = parser.parse_args()
logging.basicConfig(level=logging.INFO if opts.verbose else logging.WARNING)
log = logging.getLogger()
operation = getattr(operator, opts.operation)
log.info('Applying %s to %s', opts.operation, opts.number)
print(functools.reduce(operation, opts.number))
正确答案： D
4. 第 4 题：运行系统命令
知识点描述：在编写系统运维工具时，调用系统命令。
问题描述：编写 Linux 系统运维工具，调用系统命令查看 “/” 目录下文件，请从以下选项中选出你认为正确的选项：
A.
import shlex
import subprocess
def run(command):
try:
result = subprocess.getstatusoutput(command, shell=shlex.split(command), stderr=subprocess.STDOUT)
return 0, result
except subprocess.CalledProcessError as e:
return e.returncode, e.output
status, out = run('ls "/"')
print(status, out)
B.
import shlex
import subprocess
def run(command):
try:
result = subprocess.check_output(command, shell=shlex.split(command), stderr=subprocess.STDOUT)
return 0, result
except subprocess.CalledProcessError as e:
return e.returncode, e.output
status, out = run('ls "/"')
print(status, out)
C.
import gzip
text = 'text.txt'
with open(text, 'rt') as file:
read_text = file.read()
with gzip.open('compress.gz', 'wt', compresslevel = 9) as f:
f.write(read_text)
D.
import gzip
text = 'text.txt'
with open(text, 'rt') as file:
read_text = file.read()
with gzip.open('compress.gz', 'wt', compresslevel = 0) as f:
f.write(read_text)
正确答案：B
5. 第 5 题：命令行中进度条显示
知识点描述：使用进度条显示当前任务完成进度。
问题描述：在执行耗时任务时，使用进度条显示已经完成了的任务进度，请从以下选项中选出你认为正确的选项：
A.
import shutil, sys
import time
def progressbar(func):
def _func_with_progress(*args, **kwargs):
max_width, _ = shutil.get_terminal_size()
gen = func(*args, **kwargs)
while True:
try:
progress = next(gen)
except StopIteration as exc:
sys.stdout.write('\\n')
return exc.value
else:
message = '[%s] {}%%'.format(progress)
bar_width = max_width - len(message) + 3
filled = int(round(bar_width / 100.0 * progress))
spaceleft = bar_width - filled
bar = '=' * filled + ' ' * spaceleft
sys.stdout.write((message+'\\r') % bar)
sys.stdout.flush()
@progressbar
def wait(seconds):
start = time.time()
step = seconds / 100.
for i in range(1, 101):
time.sleep(step)
yield i
return time.time() - start
if __name__ == '__main__':
print("Waiting", wait(4))
B.
import shutil, sys
import time
def progressbar(func):
def _func_with_progress(*args, **kwargs):
max_width, _ = shutil.get_terminal_size()
gen = func(*args, **kwargs)
while True:
try:
progress = next(gen)
except StopIteration as exc:
sys.stdout.write('\\n')
return exc.value
else:
message = '[%s] {}%%'.format(progress)
bar_width = max_width - len(message) + 3
filled = int(round(bar_width / 100.0 * progress))
spaceleft = bar_width - filled
bar = '=' * filled + ' ' * spaceleft
sys.stdout.write((message+'\\r') % bar)
sys.stdout.flush()
return _func_with_progress
@progressbar
def wait(seconds):
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