大约有 36,010 项符合查询结果（耗时：0.0409秒） [XML]
eval command in Bash and its typical uses
...utput. Since $n evaluates to 1, $($n) attempts to run the command 1, which does not exist.
eval echo \${$n} runs the parameters passed to eval. After expansion, the parameters are echo and ${1}. So eval echo \${$n} runs the command echo ${1}.
Note that most of the time, you must use double quotes ...
How to implement Enums in Ruby?
...these enum is too be stored to the database? Will symbol notation works? I doubt...
– Phương Nguyễn
Jun 11 '10 at 3:44
...
Forward host port to docker container
Is it possible to have a Docker container access ports opened by the host? Concretely I have MongoDB and RabbitMQ running on the host and I'd like to run a process in a Docker container to listen to the queue and (optionally) write to the database.
...
How to use a decimal range() step value?
..., storage (for the package itself) etc. Depending on what the developer is doing, it may be impossible to use it.
– rbaleksandar
May 24 '17 at 13:56
...
Difference between open and codecs.open in Python
...en() works in Python 2.6 and all later versions, including Python 3.4. See docs: http://docs.python.org/3.4/library/io.html
Now, for the original question: when reading text (including "plain text", HTML, XML and JSON) in Python 2 you should always use io.open() with an explicit encoding, or open()...
jQuery parent of a parent
...y would probably be using closest:
$(this).closest('tr');
Check out the documentation:
Closest works by first looking at the current element to see if it matches the specified expression, if so it just returns the element itself. If it doesn't match then it will continue to traverse up the do...
How to remove trailing whitespace of all files recursively?
...Use:
find . -type f -print0 | xargs -0 perl -pi.bak -e 's/ +$//'
if you don't want the ".bak" files generated:
find . -type f -print0 | xargs -0 perl -pi -e 's/ +$//'
as a zsh user, you can omit the call to find, and instead use:
perl -pi -e 's/ +$//' **/*
Note: To prevent destroying .git d...
Parsing JSON with Unix tools
...SON from the command line, and will be a lot easier and more reliable than doing it with Awk, such as jq:
curl -s 'https://api.github.com/users/lambda' | jq -r '.name'
You can also do this with tools that are likely already installed on your system, like Python using the json module, and so avoid...
What is the difference between encrypting and signing in asymmetric encryption?
... be the sender.
I want my public key to be used to read the messages and I do not care who reads them
This is signing, it is done with your private key.
I want to be able to encrypt certain information and use it as a product key for my software.
I only care that I am the only one who can generate...
Drop unused factor levels in a subsetted data frame
...he factor variable retains all of its original levels, even when/if they do not exist in the new dataframe.
14 Answers
...