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How to check if a variable is set in Bash?
...
(Usually) The right way
if [ -z ${var+x} ]; then echo "var is unset"; else echo "var is set to '$var'"; fi
where ${var+x} is a parameter expansion which evaluates to nothing if var is unset, and substitutes the string x otherw...
Google Maps: How to create a custom InfoWindow?
...into the div with the close info window image in it.
The final loop hides all the pieces of the pointer arrow. I needed this myself as I wanted to have transparency on the infowindow and the arrow got in the way. Of course, with the hook, changing the code to replace the arrow image with a png of y...
#pragma mark in Swift?
...ractice anyway. Since extensions can implement protocols, you can e.g. put all of your table view delegate methods in an extension and group your code at a more semantic level than #pragma mark is capable of.
share
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What are the differences between Rust's `String` and `str`?
...tr most commonly2 appears as &str: a reference to some UTF-8 data, normally called a "string slice" or just a "slice". A slice is just a view onto some data, and that data can be anywhere, e.g.
In static storage: a string literal "foo" is a &'static str. The data is hardcoded into the execu...
How do I “git blame” a deleted line?
...an I find when a line that existed in a specific previous commit was eventually deleted. I'm thinking bisect , but I was hoping for something handier.
...
java.sql.SQLException: - ORA-01000: maximum open cursors exceeded
...olution:
Increasing the number of cursors on the database (if resources allow) or
Decreasing the number of threads in the application.
Cursor leak
The applications is not closing ResultSets (in JDBC) or cursors (in stored procedures on the database)
Solution: Cursor leaks are bugs; increasin...
IIS7 Overrides customErrors when setting Response.StatusCode?
...ing on value of fTrySkipCustomErrors returned in IHttpResponse::GetStatus call. When fTrySkipCustomErrors is set to true, custom error module will let the response pass through but if it is set to false, custom errors module replaces text with its own text.
More information: What to expect from II...
How do I revert a Git repository to a previous commit?
...o temporarily go back to it, fool around, then come back to where you are, all you have to do is check out the desired commit:
# This will detach your HEAD, that is, leave you with no branch checked out:
git checkout 0d1d7fc32
Or if you want to make commits while you're there, go ahead and make a n...
How to use '-prune' option of 'find' in sh?
... test (up to and including -prune) will return false for the stuff you actually want (ie: the stuff you don't want to prune out).
Here's an example:
find . -name .snapshot -prune -o -name '*.foo' -print
This will find the "*.foo" files that aren't under ".snapshot" directories. In this example, -na...
“Diff” an image using ImageMagick
... as a PNG file, the second one as a PDF.
The resulting diff file displays all pixels which are different in red color. The ones which are unchanged appear white.
Short and sweet.
Note, your images need not be the same type. You can even mix JPEG, TIFF, PNG -- under one condition: the images sho...