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echo that outputs to stderr
...criptors will refer to the same file: the one file descriptor #2 was originally referring to. For more information see the Bash Hackers Illustrated Redirection Tutorial.
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Detect the Internet connection is offline?
...et may be to just fail gracefully, preserve the data, and alert the user.. allowing them to eventually fix the connection problem if there is one, and to continue using your app with a fair amount of forgiveness.
Sidenote: You could check a reliable site like google for connectivity, but this may n...
Command to get nth line of STDOUT
...ssage:
ls -l | sed -n -e '2{p;q}'
I've seen that often enough that I usually use the first (which is easier to type, anyway), though ls is not a command that complains when it gets SIGPIPE.
For a range of lines:
ls -l | sed -n 2,4p
For several ranges of lines:
ls -l | sed -n -e 2,4p -e 20,30...
Javascript what is property in hasOwnProperty?
...ty returns a boolean value indicating whether the object on which you are calling it has a property with the name of the argument. For example:
var x = {
y: 10
};
console.log(x.hasOwnProperty("y")); //true
console.log(x.hasOwnProperty("z")); //false
However, it does not look at the prototype ...
How to handle floats and decimal separators with html5 input type number
... has a default value of 1. If you want the input's validation algorithm to allow floating-point values, specify a step accordingly.
For example, I wanted dollar amounts, so I specified a step like this:
<input type="number" name="price"
pattern="[0-9]+([\.,][0-9]+)?" step="0.01"
...
How to display gpg key details without importing it?
...from the warning.
Technical Details: Listing OpenPGP Packets
Without installing any further packages, you can use gpg --list-packets [file] to view information on the OpenPGP packets contained in the file.
$ gpg --list-packets a4ff2279.asc
:public key packet:
version 4, algo 1, created 135647...
How dangerous is it to access an array out of bounds?
... repeatedly accessing a single memory location in a tight loop could literally cause that chunk of memory to melt. Other possibilities include destroying a CRT display, and moving the read/write head of a disk drive with the harmonic frequency of the drive cabinet, causing it to walk across a table...
What is the alternative for ~ (user's home directory) on Windows command prompt?
... Powershell, which I believe you can get on XP and later (and comes preinstalled with Win7), allows you to use ~ for home directory.
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Most efficient way to cast List to List
...ot behave the same as arrays in Java. Arrays are covariant; that is, it is allowed to do this:
SubClass[] subs = ...;
BaseClass[] bases = subs;
This is allowed, because the array "knows" the type of its elements. If someone attempts to store something that isn't an instance of SubClass in the arr...
How can I pass command-line arguments to a Perl program?
...rbose); # flag
Alternatively, @ARGV is a special variable that contains all the command line arguments. $ARGV[0] is the first (ie. "string1" in your case) and $ARGV[1] is the second argument. You don't need a special module to access @ARGV.
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