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How to obtain the number of CPUs/cores in Linux from the command line?
...
The most portable solution I have found is the getconf command:
getconf _NPROCESSORS_ONLN
This works on both Linux and Mac OS X. Another benefit of this over some of the other approaches is that getconf has been around for a long time. Some of the older Linux machines I have to do development o...
What is the difference between char s[] and char *s?
...So:
char *x = "Foo";
// is approximately equivalent to:
static const char __secret_anonymous_array[] = "Foo";
char *x = (char *) __secret_anonymous_array;
Note that you must not ever attempt to modify the contents of this anonymous array via this pointer; the effects are undefined (often meaning ...
Move all files except one
...
I got something wrong when I tested the command for many items: mv ~/Linux/Old/!(Tux.png Tux1.png Tux2.png) ~/Linux/New/ It empties the whole Old -directory. What is wrong?
– Léo Léopold Hertz 준영
Mar 22 '09 ...
JSON datetime between Python and JavaScript
...
You can add the 'default' parameter to json.dumps to handle this:
date_handler = lambda obj: (
obj.isoformat()
if isinstance(obj, (datetime.datetime, datetime.date))
else None
)
json.dumps(datetime.datetime.now(), default=date_handler)
'"2010-04-20T20:08:21.634121"'
Which is ISO 8...
When is assembly faster than C?
...igh part of 64 bit integer multiplication: A portable version using uint64_t for 32x32 => 64-bit multiplies fails to optimize on a 64-bit CPU, so you need intrinsics or __int128 for efficient code on 64-bit systems.
_umul128 on Windows 32 bits: MSVC doesn't always do a good job when multiplying ...
Logger slf4j advantages of formatting with {} instead of string concatenation
...out knowing if it is needed or not (the traditional "is debugging enabled" test known from log4j), and should be avoided if possible, as the {} allows delaying the toString() call and string construction to after it has been decided if the event needs capturing or not. By having the logger format a ...
Variable interpolation in the shell
...
Use
"$filepath"_newstap.sh
or
${filepath}_newstap.sh
or
$filepath\_newstap.sh
_ is a valid character in identifiers. Dot is not, so the shell tried to interpolate $filepath_newstap.
You can use set -u to make the shell exit with an...
Git - How to use .netrc file on Windows to save user and password
...onment variable %HOME% (pre-Git 2.0, no longer needed with Git 2.0+)
put a _netrc file in %HOME%
If you are using Windows 7/10, in a CMD session, type:
setx HOME %USERPROFILE%
and the %HOME% will be set to 'C:\Users\"username"'.
Go that that folder (cd %HOME%) and make a file called '_netrc'
N...
How to write very long string that conforms with PEP8 and prevent E501
....
from paragraphs import par
class SuddenDeathError(Exception):
def __init__(self, cause: str) -> None:
self.cause = cause
def __str__(self):
return par(
f""" Y - e - e - e - es, Lord love you! Why should she die of
{self.cause}? She come throug...
How to easily map c++ enums to strings
...::strings in the map)
For extra syntactic sugar, here's how to write a map_init class. The goal is to allow
std::map<MyEnum, const char*> MyMap;
map_init(MyMap)
(eValue1, "A")
(eValue2, "B")
(eValue3, "C")
;
The function template <typename T> map_init(T&) returns a ma...