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What is the $? (dollar question mark) variable in shell scripting? [duplicate]
...(This was also
suggested by mike)
#!/bin/bash
cd /dada &> /dev/null
echo rv: $?
cd $(pwd) &> /dev/null
echo rv: $?
See Bash Programming Manual for more details.
sha...
How to add leading zeros for for-loop in shell? [duplicate]
... that this feature got introduced with bash-4.0-alpha: Brace expansion now allows zero-padding of expanded numeric values and will add the proper number of zeroes to make sure all values contain he same number of digits.).
– Adrian Frühwirth
Feb 13 '15 at 18:5...
Do you need to use path.join in node.js?
... only real issue is that Windows command-line processors (or, more specifically, Windows-native command-line utilities) tend to interpret forward slashes as option specifiers rather than path components. Therefore, you need a backslashed path if you need to pass a path to a Windows command run as a ...
How to import an excel file in to a MySQL database
...s. Here is a recent example I used to import a csv file named test.csv.
phpMyAdmin: Select your database first, then select the Import tab. phpMyAdmin will automatically create your table and size your VARCHAR fields, but it won't optimize the field types. phpMyAdmin has trouble importing large...
In which situations do we need to write the __autoreleasing ownership qualifier under ARC?
...his is very well explained in the ARC transition guide.
In your NSError example, the declaration means __strong, implicitly:
NSError * e = nil;
Will be transformed to:
NSError * __strong error = nil;
When you call your save method:
- ( BOOL )save: ( NSError * __autoreleasing * );
The compi...
How do I get the logfile from an Android device?
... reader.readLine()) != null) {
if (currentLine != null && currentLine.contains(String.valueOf(pid))) {
result.append(currentLine);
result.append("\n");
}
}
FileWriter out = new FileW...
Underscore vs Double underscore with variables and methods [duplicate]
...
I love this explanation!! So short & sweet, but gets the whole concept across clearly. I would only add an example of the name-changing: how __foo() in Class1 and Class2 becomes _Class1__foo() and _Class2__foo()
– Casey Jones
...
Python matplotlib multiple bars
How to plot multiple bars in matplotlib, when I tried to call the bar function multiple times, they overlap and as seen the below figure the highest value red can be seen only.
How can I plot the multiple bars with dates on the x-axes?
...
What is the difference between Google App Engine and Google Compute Engine?
...d. But the restriction is, you can create your application in only Python, PHP, Java, NodeJS, .NET, Ruby and **Go.
On the other hand, GCE provides you full infrastructure in the form of Virtual Machine. You have complete control over those VMs' environment and runtime as you can write or install an...
process.env.NODE_ENV is undefined
...
tips
in package.json:
"scripts": {
"start": "set NODE_ENV=dev && node app.js"
}
in app.js:
console.log(process.env.NODE_ENV) // dev
console.log(process.env.NODE_ENV === 'dev') // false
console.log(process.env.NODE_ENV.length) // 4 (including a space at the end)
so, this ma...