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My docker container has no internet
...n docker daemon.json
Edit /etc/docker/daemon.json
{
"dns": ["10.1.2.3", "8.8.8.8"]
}
Restart the docker daemon for those changes to take effect:
sudo systemctl restart docker
Now when you run/start a container, docker will populate /etc/resolv.conf with the values from daemon.json.
2. Fi...
Adding a column to an existing table in a Rails migration
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edited Oct 24 '19 at 10:35
ARK
54755 silver badges1818 bronze badges
answered Jan 29 '11 at 3:10
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Is there a performance difference between i++ and ++i in C++?
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432
[Executive Summary: Use ++i if you don't have a specific reason to use i++.]
For C++, the answ...
How to mount a host directory in a Docker container
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38
This worked for me on mac os x with docker-machine and VirtualBox. One caveat I discovered by trial and error is that the host directory mu...
Run a single migration file
... of the ruby file:
rails console
>> require "db/migrate/20090408054532_add_foos.rb"
>> AddFoos.up
Note: newer versions of rails may require AddFoos.new.up rather than AddFoos.up.
An alternative way (without IRB) which relies on the fact that require returns an array of class names:
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How to duplicate a whole line in Vim?
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edited Jul 10 '19 at 22:30
iono
2,38211 gold badge2323 silver badges3434 bronze badges
answered Sep 16...
How do I safely pass objects, especially STL objects, to and from a DLL?
...undamental datatypes have the same sizes regardless of whether your app is 32-bit or 64-bit. However, since the size of a given datatype is enforced by the compiler, not by any standard (all the standard guarantees is that 1 == sizeof(char) <= sizeof(short) <= sizeof(int) <= sizeof(long) &l...
Returning unique_ptr from functions
...clause in the language specification that this exploits?
Yes, see 12.8 §34 and §35:
When certain criteria are met, an implementation is allowed to omit the copy/move construction of a class object [...]
This elision of copy/move operations, called copy elision, is permitted [...]
in a re...
In Docker, what's the difference between a container and an image? [duplicate]
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13 Answers
13
Active
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Changing Java Date one hour back
...k = cal.getTime();
java.util.Date
new Date(System.currentTimeMillis() - 3600 * 1000);
org.joda.time.LocalDateTime
new LocalDateTime().minusHours(1)
Java 8: java.time.LocalDateTime
LocalDateTime.now().minusHours(1)
Java 8 java.time.Instant
// always in UTC if not timezone set
Instant.now(...