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What are the special dollar sign shell variables?
... $3, ... are the positional parameters.
"$@" is an array-like construct of all positional parameters, {$1, $2, $3 ...}.
"$*" is the IFS expansion of all positional parameters, $1 $2 $3 ....
$# is the number of positional parameters.
$- current options set for the shell.
$$ pid of the current shell (...
What is the use of “assert” in Python?
...t True # nothing happens
>>> assert False
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AssertionError
Assertions can include an optional message, and you can disable them when running the interpreter.
To print a message if the assertion fails:
ass...
Delete directory with files in it?
I wonder, what's the easiest way to delete a directory with all its files in it?
33 Answers
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How do you add a Dictionary of items into another Dictionary
...n drop the @assignment and return, you're already mutating left. Edit: actually, even though I get no errors, I think @assignment should stay.
– Roland
Jun 9 '14 at 12:02
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Is there any Rails function to check if a partial exists?
..., I'm using the following in my Rails 3/3.1 projects:
lookup_context.find_all('posts/_form').any?
The advantage over other solutions I've seen is that this will look in all view paths instead of just your rails root. This is important to me as I have a lot of rails engines.
This also works in R...
How to print SQL statement in codeigniter model
...
when i do print_r($query); nothing prints out at all
– Technupe
May 26 '11 at 16:50
1
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Cookies on localhost with explicit domain
...unction.setcookie.php#73107.
If working with the Java Servlet API, don't call the cookie.setDomain("...") method at all.
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How to save an HTML5 Canvas as an image on a server?
I'm working on a generative art project where I would like to allow users to save the resulting images from an algorithm. The general idea is:
...
Which commit has this blob?
... scripts take the blob’s SHA1 as the first argument, and after it, optionally, any arguments that git log will understand. E.g. --all to search in all branches instead of just the current one, or -g to search in the reflog, or whatever else you fancy.
Here it is as a shell script – short and sw...
Convert pem key to ssh-rsa format
...m assuming no password for the keys (which is bad).
Generate an RSA pair
All the following methods give an RSA key pair in the same format
With openssl (man genrsa)
openssl genrsa -out dummy-genrsa.pem 2048
In OpenSSL v1.0.1 genrsa is superseded by genpkey so this is the new way to do it (man...