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What command means “do nothing” in a conditional in Bash?
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The no-op command in shell is : (colon).
if [ "$a" -ge 10 ]
then
:
elif [ "$a" -le 5 ]
then
echo "1"
else
echo "2"
fi
From the bash manual:
: (a colon)
Do nothing beyond expanding arguments and performing redirections....
Ignore python multiple return value
...= func()[0] to return the first value, x = func()[1] to return the second, and so on.
If you want to get multiple values at a time, use something like x, y = func()[2:4].
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Git format-patch to be svn compatible?
...ch with git diff --no-prefix master..branch > somefile.diff, the master and branch part are optional, depends how you want to get your diffs.
Send it wherever and apply with patch -p0 < somefile.diff.
It always seems to work fine for me and seems to be the simplest method that I've come acr...
Rails - How to use a Helper Inside a Controller
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Note: This was written and accepted back in the Rails 2 days; nowadays grosser's answer is the way to go.
Option 1: Probably the simplest way is to include your helper module in your controller:
class MyController < ApplicationController
inc...
How to update Identity Column in SQL Server?
I have SQL Server database and I want to change the identity column because it started
with a big number 10010 and it's related with another table, now I have 200 records and I want to fix this issue before the records increases.
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The project type is not supported by this installation
... edit please see the answer further down, which is about 18 months newer, and actually solves the problem. This historically once-accurate answer is no longer as accurate. Leaving intact after the break for this reason. - thanks - jcolebrand
What edition of VS do you use? VS2008 Express, Standa...
Comparing two dataframes and getting the differences
...This approach, df1 != df2, works only for dataframes with identical rows and columns. In fact, all dataframes axes are compared with _indexed_same method, and exception is raised if differences found, even in columns/indices order.
If I got you right, you want not to find changes, but symmetric d...
How to pass arguments and redirect stdin from a file to program run in gdb?
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Pass the arguments to the run command from within gdb.
$ gdb ./a.out
(gdb) r < t
Starting program: /dir/a.out < t
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Converting an array of objects to ActiveRecord::Relation
... ActiveRecord::Relation since a Relation is just a builder for a SQL query and its methods do not operate on actual data.
However, if what you want is a relation then:
for ActiveRecord 3.x, don’t call all and instead call scoped, which will give back a Relation which represents the same records...
Android - startActivityForResult immediately triggering onActivityResult
... in my app using the call startActivityForResult(intent, ACTIVITY_TYPE) , and they are all working but one.
13 Answers
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