counting the remaining memory of the system
In [1]: S1 = ' abc '
In [2]: Help (S1.startswith)
Help on built-in function StartsWith:
StartsWith (...)
S.startswith (prefix[, start[, end]), BOOL
Return True If S starts with the specified prefix, False otherwise.
With optional start, test S beginning on that position.
With optional end, stop comparing S on that position.
Prefix can also is a tuple of strings to try.
(END)
Cat/proc/meminfo
#!/usr/bin/python
With open ('/proc/meminfo ') as FD:
For line in FD:
If Line.startswith (' Memtotal: '):
Total = Line.split () [1]
Continue
If Line.startswith (' Memfree: '):
Free = Line.split () [1]
Break
Print "%.2f"% (int (free)/1024.0) + ' M '
Data type conversion calculation (Compute MAC address)
10 binary converted to 16 binary:
In [9]: Hex (10)
OUT[9]: ' 0xa '
16 binary converted to 10 binary:
In [8]: Int (' 0xa ', 16)
OUT[8]: 10
In [7]: Int (' AA ', 16)
OUT[7]: 170
A string of pure numbers is converted into 10 binary:
In [ten]: Int (' 10 ')
OUT[10]: 10
10 binary converted to string:
In [All]: STR (10)
OUT[11]: ' 10 '
Example:
Original server mac:02:42:0e:31:98:0b, write script to generate the next Nic Mac, automatically add 1.
#!/usr/bin/python
macaddr = ' 02:42:0e:31:98:0b '
Prefix_mac = macaddr[:-3]
Last_two = macaddr[-2:]
plus_one = Int (last_two,16) +1
If Plus_one in range (10):
New_last_two = Hex (Plus_one) [2:]
New_last_two = ' 0 ' + new_last_two
Else
New_last_two = Hex (Plus_one) [2:]
If Len (new_last_two) = = 1:
New_last_two = ' 0 ' +new_last_two
New_mac = Prefix_mac + ': ' + new_last_two
Print New_mac.upper ()
Data type conversions (lists and dictionaries convert each other)
View Help Join ()
Help on built-in function join:
Join (...)
S.join (iterable), string
Return a string which is the concatenation of the strings in the
Iterable. The separator between elements is S.
(END)
String-To-Lists: list (string)
In [approx]: a = list (' AAA ')
In [PNS]: type (a)
OUT[37]: List
In []: a
OUT[38]: [' A ', ' a ', ' a ']
List to string: '. Join (list)
In []: a
OUT[38]: [' A ', ' a ', ' a ']
in [39]:l = a
in []: l
OUT[18]: [' A ', ' a ', ' a ']
in [+]: '. Join (L)
OUT[19]: ' AAA '
in []: ', '. Join (L)
OUT[20]: ' A,a,a '
In [21]: '. '. Join (L)
OUT[21]: ' A.A.A '
In []: A= ' a '
In [All]: Help (A.join)
String tuples: Tuple (String)
In []: s
OUT[24]: [' A ', ' a ', ' a ']
in [+]: tuple (s)
OUT[26]: (' A ', ' a ', ' a ')
Tuple to string: '. Join (tuple)
In [SI]: type (a)
OUT[54]: Tuple
in [+]: a = str (a)
in [+]: A
OUT[56]: "(' A ', ' B ', ' C ', 111)"
In [the]: type (a)
OUT[57]: Str
Dictionary goto list:
in [+]: dic = {' A ': 1, ' B ': 2}
in [+]: dic
OUT[29]: {' A ': 1, ' B ': 2}
in [+]: Dic.items ()
OUT[30]: [(' A ', 1), (' B ', 2)]
List to Dictionary:
In [to]: L1 = Dic.items ()
in [+]: L1
OUT[32]: [(' A ', 1), (' B ', 2)]
In [All]: type (L1)
OUT[33]: List
In [the]: dict (L1)
OUT[34]: {' A ': 1, ' B ': 2}
Examples of data type conversions in Python and script statistics server memory instances