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Fastest way to tell if two files have the same contents in Unix/Linux?
...e same data or not. I do this a for a lot of files, and in my script the diff command seems to be the performance bottleneck.
...
do..end vs curly braces for blocks in Ruby
...-line blocks and curly braces for single line blocks, but there is also a difference between the two that can be illustrated with this example:
puts [1,2,3].map{ |k| k+1 }
2
3
4
=> nil
puts [1,2,3].map do |k| k+1; end
#<Enumerator:0x0000010a06d140>
=> nil
This means that {} has a high...
“unary operator expected” error in Bash if condition
...
If you know you're always going to use bash, it's much easier to always use the double bracket conditional compound command [[ ... ]], instead of the Posix-compatible single bracket version [ ... ]. Inside a [[ ... ]] compou...
Detect if a NumPy array contains at least one non-numeric value?
I need to write a function which will detect if the input contains at least one value which is non-numeric. If a non-numeric value is found I will raise an error (because the calculation should only return a numeric value). The number of dimensions of the input array is not known in advance - the fu...
How to check if a value exists in a dictionary (python)
... in case you wonder why... the reason is that each of the above returns a different type of object, which may or may not be well suited for lookup operations:
>>> type(d.viewvalues())
<type 'dict_values'>
>>> type(d.values())
<type 'list'>
>>> type(d.itervalue...
How to know if user is logged in with passport.js?
...
If user is logged in, passport.js will create user object in req for every request in express.js, which you can check for existence in any middleware:
if (req.user) {
// logged in
} else {
// not logged in
}
You ca...
How can I programmatically get the MAC address of an iphone
... MAC
Somthing I stumbled across a while ago. Originally from here I modified it a bit and cleaned things up.
IPAddress.h
IPAddress.c
And to use it
InitAddresses();
GetIPAddresses();
GetHWAddresses();
int i;
NSString *deviceIP = nil;
for (i=0; i<MAXADDRS; ++i)
{
static unsigned long lo...
Recursive sub folder search and return files in a list python
...dirpath which you call root. The dirnames are supplied so you can prune it if there are folders that you don't wish os.walk to recurse into.
import os
result = [os.path.join(dp, f) for dp, dn, filenames in os.walk(PATH) for f in filenames if os.path.splitext(f)[1] == '.txt']
Edit:
After the late...
Check if instance is of a type
Using this to check if c is an instance of TForm .
9 Answers
9
...
Check Whether a User Exists
...n also check user by id command.
id -u name gives you the id of that user.
if the user doesn't exist, you got command return value ($?)1
And as other answers pointed out: if all you want is just to check if the user exists, use if with id directly, as if already checks for the exit code. There's no ...