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add column to mysql table if it does not exist
...
OK this is really crude but someone's got to say it. if you are simply running a SQL script from the command line, you can give mysql the --force switch, which means keep going even if there's an error. then, just go for it. you just want...
How do I set a variable to the output of a command in Bash?
... be done with $(command) or "$(command)", which I find easier to read, and allows for nesting.
OUTPUT=$(ls -1)
echo "${OUTPUT}"
MULTILINE=$(ls \
-1)
echo "${MULTILINE}"
Quoting (") does matter to preserve multi-line variable values; it is optional on the right-hand side of an assignment, as w...
二进制数据专题：蓝牙、Socket、WebSocket、MQTT 收发字节 · App Inventor 2 中文网
...多不是发一句文本，而是发一串字节：
「帧头 A5、命令 01、两个字节的温度、一个字节的校验」。这类格式叫二进制协议。
App Inventor 里处理二进制只需要记住一件事：字节列表就是由 0~255 的数字组成的普通列表。
下面这些组...
Why does Eclipse automatically add appcompat v7 library support whenever I create a new project?
Why does Eclipse automatically add appcompat v7 library support whenever I create a new project?
10 Answers
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What is a good Java library to zip/unzip files? [closed]
... zipFile.setPassword(password);
}
zipFile.extractAll(destination);
} catch (ZipException e) {
e.printStackTrace();
}
}
The Maven dependency is:
<dependency>
<groupId>net.lingala.zip4j</groupId>
<artifactId>zip4j</artifac...
How to quietly remove a directory with content in PowerShell
...o remove everything within that folder: Remove-Item './folder/*'. If you really want to clear out only files of all folders you can list all leafs and pipe it to the Remove-Item cmdlet Get-ChildItem -Recurse -File | Remove-Item
– Michael Kargl
Jun 1 '19 at 11:3...
Clang vs GCC - which produces faster binaries? [closed]
...d
by the fact that any number of tests which take 0 measurable time will
all add up to 0, but the contribution of such tests is negligible. The
timing stats are displayed at the end of make check like this:
coan_test_timer: info: coan processed 70844 input_files.
coan_test_timer: info: run time ...
How do I get the day of the week with Foundation?
...
NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
[dateFormatter setDateFormat:@"EEEE"];
NSLog(@"%@", [dateFormatter stringFromDate:[NSDate date]]);
outputs current day of week as a string in locale dependent on current regional settings.
To g...
Measuring function execution time in R
... preferred way to know the time it takes for a long calculation done in parallel on multiple cores. In this case, the wall clock time measured through this call is accurate enough since the computer will be much busier with all cores calculating than doing anything else and the calculations take min...
Insert space before capital letters
...camelCase to Regular Form
"thisStringIsGood"
// insert a space before all caps
.replace(/([A-Z])/g, ' $1')
// uppercase the first character
.replace(/^./, function(str){ return str.toUpperCase(); })
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