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How to ignore xargs commands if stdin input is empty?
...t;#args>, -i, and -I <string>:
ls /empty_dir/ | xargs -n10 chown root # chown executed every 10 args or fewer
ls /empty_dir/ | xargs -L10 chown root # chown executed every 10 lines or fewer
ls /empty_dir/ | xargs -i cp {} {}.bak # every {} is replaced with the args from one input line
ls /...
How do I get an apk file from an Android device?
...missions to access the directory your file is in. If not, you will need to root the device first.
If you find that many of the APKs are named "base.apk" you can also use this one line command to pull all the APKs off a phone you can access while renaming any "base.apk" names to the package name. ...
How to pass arguments to a Button command in Tkinter?
...
Example GUI:
Let's say I have the GUI:
import tkinter as tk
root = tk.Tk()
btn = tk.Button(root, text="Press")
btn.pack()
root.mainloop()
What Happens When a Button Is Pressed
See that when btn is pressed it calls its own function which is very similar to button_press_handle in t...
How to change the output color of echo in Linux
...?
Anywhere that has a tty interpreter
xterm, gnome-terminal, kde-terminal, mysql-client-CLI and so on.
For example if you want to colorize your output with mysql you can use Perl
#!/usr/bin/perl -n
print "\033[1m\033[31m$1\033[36m$2\033[32m$3\033[33m$4\033[m" while /([|+-]+)|([0-9]+)|([a-zA-Z_]+)|([...
How to get last inserted id?
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I'm coming from a mysql background, I can't understand this command: Int32 newId = (Int32) myCommand.ExecuteScalar();
– Naguib Ihab
May 28 '15 at 1:23
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Very simple log4j2 XML configuration file using Console and File appender
... </File>
</Appenders>
<Loggers>
<Root level="debug">
<AppenderRef ref="Console" />
<AppenderRef ref="MyFile"/>
</Root>
</Loggers>
</Configuration>
Notes:
Put the following content in yo...
Does a UNIQUE constraint automatically create an INDEX on the field(s)?
...email, user_id) is enough, you don't need a separate index on email only - MySQL can use leftmost parts of a composite index. There may be some border cases where the size of an index can slow down your queries, but you should not worry about them until you actually run into them.
As for testing in...
Does Foreign Key improve query performance?
...
foreign keys do improve performance, at least in MySQL. Moreover, you're right, the creation of a FK does not create an index; the creation of a FK requires an index
– Félix Gagnon-Grenier
Aug 26 '14 at 17:31
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ASP.NET 2.0 - How to use app_offline.htm
I've read about the app_offline.htm file which can be placed within the root of a .NET 2.0 application which will in essence shut down the application and disable any other pages from being requested.
...
Are duplicate keys allowed in the definition of binary search trees?
...a BST which allows either of the right or left children to be equal to the root node, will require extra computational steps to finish a search where duplicate nodes are allowed.
It is best to utilize a list at the node to store duplicates, as inserting an '=' value to one side of a node requires r...