Sys module

Sys. argv: Implements passing parameters from outside the program to the program.

The positional argument argv[0] represents the py file itself, and runs the method python xx.py with arguments 1 and 2.

self = sys.argv[0]
name = sys.argv[1]
age = sys.argv[2]
print self, name, age
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Sys.getdefaultencoding (): Gets the current encoding of the system, usually ASCII by default.

print sys.getdefaultencoding()
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Sys.setdefaultencoding (): Sets the system default coding,

If dir (sys) doesn’t work, you can reload(sys) and setDefaultencoding (‘utf8’), then the defaultencoding is set to UTF8. (python2.7 may require this)

reload(sys)
sys.setdefaultencoding('utf8')
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Sys. path: Gets a collection of strings for the specified module search path

sys.path
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Sys. platform: obtains the current system platform.

print sys.platform
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sys.exit()

Function: At the end of the main program, the interpreter automatically exits, but if you need to exit the program halfway through, you can call sys.exit, which is returned to the calling program with an optional integer argument, meaning you can catch calls to sys.exit in the main program. (0 is normal exit, other is exception)

for i in range(1, 10):
    print '%s time :' % i, i
    if i == 5:
        print 'Fifth exit'
        sys.exit(0)
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OS module

Os.name () — Determine which platform is being used, Windows returns’ nt’; Linux returns’ posix ‘

print os.name()
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Os.getcwd () — get the current working directory.

print os.getcwd()
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Os.listdir () — Specifies all files and directory names under all directories.

print os.listdir('. ')
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4. Os.remove () — Removes the specified file

os.remove('aaa.txt')
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Os.rmdir () — Deletes the specified directory

os.rmdir('C://Users/xiaoxinsoso/Desktop/aaa')
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6. Os.mkdir () — Create a directory, note: this can only create a single layer, to build recursively: os.makedirs()

os.makedirs('aaa/aaa')
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Os.path.isfile () — Checks whether the specified object is a file. Returns True if True, False otherwise

print os.path.isfile('ccc.txt')
print os.path.isfile('aaa')
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Os.path.isdir () — Checks whether the specified object is a directory. Is True, otherwise False. Ex. :

print os.path.isdir('aaa')
print os.path.isdir('ccc.txt')
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9. Os.path.exists () — Checks whether the specified object exists. True, otherwise False. Example:

print os.path.exists('bbb')
print os.path.exists('aaa')
print os.path.exists('ccc.txt')
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10.os.path.split () — Returns the directory and file name of the path. Ex. :

print os.path.split('C://Users/xiaoxinsoso/Desktop/aaa/ccc.txt')
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Os.getcwd () — Get the current working directory

print os.getcwd()
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Os.system () — Execute the shell command.

Note: When running shell commands here, if you want to call a previous Python variable, you can do the following:

var = 123
os.environ['var'] = str(var) # note that [] must be "string"
os.system('echo $var')

os.system('dir')
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13. Os.chdir () — Change the directory to the specified directory

Os.path.getsize () — Gets the size of the file, or 0 if it is a directory

print os.path.getsize('ccc.txt')
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Os.path.abspath () — Get the absolute path. Ex. :

print os.path.abspath('. ')
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Os.path. join(path, name) — Join directory and file name. Ex. :

print os.path.join('c://user/xiaoxinsoso/'.'wenjian.txt')
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Os.path.basename (path) — Returns the file name

print os.path.basename('ccc.txt')
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Os.path.dirname (path) — Returns the file path

print os.path.dirname('C://Users/xiaoxinsoso/Desktop/aaa/ccc.txt')
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19. Get the actual directory where the program resides

if __name__ == "__main__":
    print os.path.realpath(sys.argv[0])
    print os.path.split(os.path.realpath(sys.argv[0]))
    print os.path.split(os.path.realpath(sys.argv[0]))[0]
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Time module

ticks = time.time()
print "The current timestamp is :", ticks
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Get the current time

localtime = time.localtime(time.time())
print "Local time is :", localtime
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Gets the time of formatting

localtime = time.asctime(time.localtime(time.time()))
print "Local time is :", localtime
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Formatting date

Format it into the 2017-01-22 16:36:27 format

print time.strftime("%Y-%m-%d %H:%M:%S", time.localtime())
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Format to Sun Jan 22 16:36:27 2017

print time.strftime("%a %b %d %H:%M:%S %Y", time.localtime())
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Converts a format string to a timestamp

a = "Sat Mar 28 22:24:24 2016"
print time.mktime(time.strptime(a, "%a %b %d %H:%M:%S %Y"))
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Get the calendar of the month

cal = calendar.month(2017, 1)
print "Output the calendar for January 2016 :"
print cal
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Datetime module

Datetime Indicates the time type

now = datetime.datetime.now()
print now
now = date time.datetime.now()
yes_time = now + date time.timedelta(days=-1)    # The day before
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Turn a datetime string

strdatetime = now.strftime("%Y-%m-%d %H:%M:%S")     # Display time as a string
strdatetime1= now.strftime("%Y-%m-%d")     # Display the time as a string, only the date
print strdatetime
print strdatetime1
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The string to turn a datetime

datetime1 = datetime.datetime.strptime(strdatetime1, "%Y-%m-%d")
print datetime1
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Datetime to timestamp

time_time = time.mktime(datetime1.timetuple())
print time_time
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Timestamp to string

time1 = time.strftime('%Y-%m-%d',time.localtime(time_time))
print time1
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Turn the date a datetime

date1 = datetime.date(2012, 11, 19)
date = datetime.date.today()
print date
print datetime.datetime.strptime(str(date),'%Y-%m-%d') Convert date to STR, convert STR to datetime
print datetime.datetime.strptime(str(date1),'%Y-%m-%d') Convert date to STR, convert STR to datetime
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