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Git - fatal: Unable to create '/path/my_project/.git/index.lock': File exists
...y. The error message is rather explicit as to what causes it typically, so if you have no other git processes running (which is the normal case), go ahead and delete that file.
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What is the difference between Amazon S3 and Amazon EC2 instance?
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Thank you for the reply. So, if I have an EC2 instance and S3 storage, can I manage to run a server(PHP, mysql)? Or is EC2 instance enough to run a server?
– Sangam254
Jan 18 '13 at 4:56
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Twitter bootstrap scrollable table
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You can only add a height percentage if the parent container has a pixel height. In your case, you'd need to do something like set .row to 500px and .span3 to 50%. If the parent doesn't have a set height the browser just defaults to the content height if you giv...
CKEditor automatically strips classes from div
...he code to how it sees fit whenever I press the source button. For example if I hit source and create a <div> ...
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What can I use instead of the arrow operator, `->`?
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@TimSeguine If you ever want to see pretty code, then look at the documentation for inside the Macintosh. I think they invented CamelCase. Very descriptive variable names and elegantly formatted code. They managed to make their later C...
Start an Activity with a parameter
...y:
Bundle b = getIntent().getExtras();
int value = -1; // or other values
if(b != null)
value = b.getInt("key");
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Remove NA values from a vector
...st what you're asking for:
d <- c(1, 100, NA, 10)
max(d, na.rm=TRUE)
If you do want to remove all of the NAs, use this idiom instead:
d <- d[!is.na(d)]
A final note: Other functions (e.g. table(), lm(), and sort()) have NA-related arguments that use different names (and offer different o...
Why is the .bss segment required?
...derstand is why do we have dedicated segment for uninitialized variables? If an uninitialised variable has a value assigned at run time, does the variable exist still in the .bss segment only?
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What is a dependency property?
...is a dependency property in .Net (especially in WPF context). What is the difference from the regular property?
3 Answers
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Select rows which are not present in other table
...nated unless EXCEPT ALL is used.
Typically, you'll want the ALL keyword. If you don't care, still use it because it makes the query faster.
NOT IN
Only good without NULL values or if you know to handle NULL properly. I would not use it for this purpose. Also, performance can deteriorate with big...