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What are file descriptors, explained in simple terms?
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COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
sleep 14726 root cwd DIR 8,1 4096 1201140 /home/x
sleep 14726 root rtd DIR 8,1 4096 2 /
sleep 14726 root txt REG 8,1 35000 786587 /bin/sleep
sleep 14726 root mem REG 8,1 11864720 118650...
Insert into a MySQL table or update if exists
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Check out REPLACE
http://dev.mysql.com/doc/refman/5.0/en/replace.html
REPLACE into table (id, name, age) values(1, "A", 19)
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Simplest way to profile a PHP script
... all the data
$select_query = "SELECT * FROM data_table";
$result = mysql_query($select_query);
prof_flag("Retrieve data");
$rows = array();
$found_data=false;
while($r = mysql_fetch_assoc($result))
{
$found_data=true;
$rows[] = $r;
}
prof_flag("Close DB");
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Why is SSE scalar sqrt(x) slower than rsqrt(x) * x?
...th on an Intel Core Duo, and while looking at various approaches to square root I've noticed something odd: using the SSE scalar operations, it is faster to take a reciprocal square root and multiply it to get the sqrt, than it is to use the native sqrt opcode!
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Delete files older than 15 days using PowerShell
... days from the current date and compare CreationTime against that value:
$root = 'C:\root\folder'
$limit = (Get-Date).AddDays(-15)
Get-ChildItem $root -Recurse | ? {
-not $_.PSIsContainer -and $_.CreationTime -lt $limit
} | Remove-Item
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How do I adb pull ALL files of a folder present in SD Card
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If you want to pull a folder owned by root, start an adb root session (using $ adb root).
– MasterAM
Jun 12 '14 at 13:32
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Python class inherits object
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Calling the root class object isn't all that confusing, and in fact it's pretty standard. Smalltalk has a root class named Object, and a root metaclass named Class. Why? Because, just as Dog is a class for dogs, Object is a class for obj...
What are the applications of binary trees?
...hing when you balance them. This involves rotating sub-trees through their root node so that the height difference between any two sub-trees is less than or equal to 1. Adding those names above one at a time into a balanced tree would give you the following sequence:
1. Alice
/ \
= ...
How can I do an UPDATE statement with JOIN in SQL Server?
...Here are some ways to do it in ANSI/ISO (aka should work on any SQL DBMS), MySQL, SQL Server, and Oracle. Be advised that my suggested ANSI/ISO method will typically be much slower than the other two methods, but if you're using a SQL DBMS other than MySQL, SQL Server, or Oracle, then it may be the ...