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Command to get nth line of STDOUT
...ssage:
ls -l | sed -n -e '2{p;q}'
I've seen that often enough that I usually use the first (which is easier to type, anyway), though ls is not a command that complains when it gets SIGPIPE.
For a range of lines:
ls -l | sed -n 2,4p
For several ranges of lines:
ls -l | sed -n -e 2,4p -e 20,30...
CORS: Cannot use wildcard in Access-Control-Allow-Origin when credentials flag is true
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This is a part of security, you cannot do that. If you want to allow credentials then your Access-Control-Allow-Origin must not use *. You will have to specify the exact protocol + domain + port. For reference see these questions :
Access-Control-Allow-Origin wildcard subdomains, ports...
Why is the C++ STL is so heavily based on templates? (and not on *interfaces*)
...OOP code, but it also had a turing-complete template language overlaid, it allowed compile-time metaprogramming, and people had discovered generic programming. Suddenly, OOP just didn't seem all that important. Not when we can write simpler, more concise and more efficient code by using techniques a...
Why should I not wrap every block in “try”-“catch”?
...f a method can throw an exception then it is reckless not to protect this call with a meaningful try block.
16 Answers
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Java - Convert integer to string [duplicate]
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they are practically the same (the last one invokes the first one, and the 2nd one is compiled to the first one). I prefer the 1st one
– Bozho
Jun 3 '13 at 9:39
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Css height in percent not working [duplicate]
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You need to set a 100% height on all your parent elements, in this case your body and html. This fiddle shows it working.
html, body { height: 100%; width: 100%; margin: 0; }
div { height: 100%; width: 100%; background: #F52887; }
<html><body...
What are DDL and DML?
...database
DROP – delete objects from the database
TRUNCATE – remove all records from a table, including all spaces allocated for the records are removed
COMMENT – add comments to the data dictionary
RENAME – rename an object
DML
DML is short name of Data Manipulation Lang...
Is memcached a dinosaur in comparison to Redis? [closed]
...ould not care too much about performances. Redis is faster per core with small values, but memcached is able to use multiple cores with a single executable and TCP port without help from the client. Also memcached is faster with big values in the order of 100k. Redis recently improved a lot about bi...
How to use concerns in Rails 4
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So I found it out by myself. It is actually a pretty simple but powerful concept. It has to do with code reuse as in the example below. Basically, the idea is to extract common and / or context specific chunks of code in order to clean up the models and avoid them...
How do you declare an interface in C++?
...virtual method list of your interface by adding a virtual destructor. This allows you to pass pointer ownership to another party without exposing the concrete derived class. The destructor doesn't have to do anything, because the interface doesn't have any concrete members. It might seem contradicto...