[NetHogs][1] is probably what you&#39;re looking for:
&gt; a small &#39;net top&#39; tool. Instead of breaking the traffic down per protocol or per subnet, like most tools do, **it groups bandwidth by process**.
&gt;
NetHogs does not rely on a special kernel module to be loaded. If there&#39;s suddenly a lot of network traffic, you can fire up NetHogs and immediately see which PID is causing this. This makes it easy to identify programs that have gone wild and are suddenly taking up your bandwidth.
&gt;
Since NetHogs heavily relies on /proc, most features are only available on Linux. NetHogs can be built on Mac OS X and FreeBSD, but it will only show connections, not processes...

[1]: https://github.com/raboof/nethogs


Also [iftop][1]:
&gt; 
###display bandwidth usage on an interface
&gt; 
iftop does for network usage what top(1) does for CPU usage. It listens to network traffic on a named interface and displays a table of current bandwidth usage by pairs of hosts. Handy for answering the question &quot;why is our ADSL link so slow?&quot;...


  [1]: http://ex-parrot.com/~pdw/iftop/

[iptraf][1] is my favorite. It has a nice ncurses interface, and options for filtering, etc. 

![enter image description here][2]


  [1]: http://iptraf.seul.org/
  [2]: http://i.stack.imgur.com/BKydV.png

[jnettop][1] is another candidate.


  [1]: https://sourceforge.net/projects/jnettop/
edit: it only shows the streams, not the owner processes.

[ntop][1] or [nagios][2]&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;


  [1]: http://www.ntop.org/
  [2]: http://www.nagios.org

Check [bmon][1]. It&#39;s cli, simple and has charts.

Not exactly what question asked - it doesn&#39;t split by processes, only by network interfaces.


  [1]: https://github.com/tgraf/bmon

Another option you could try is [iptstate][1].


  [1]: http://linuxcommand.org/man_pages/iptstate8.html

OK, I&#39;m aware that triple-quotes strings can serve as multiline comments. For example,

    &quot;&quot;&quot;Hello, I am a 
       multiline comment&quot;&quot;&quot;
and 
  
    &#39;&#39;&#39;Hello, I am a 
       multiline comment&#39;&#39;&#39;

But technically speaking these are strings, correct?

I&#39;ve googled and read the Python style guide, but I was unable to find a technical answer to why there is no formal implementation of multiline, /* */ type of comments. I have no problem using triple quotes, but I am a little curious as to what led to this design decision.


Why doesn&#39;t Python have multiline comments?

I&#39;m wondering if this is possible in SQL. Say you have two tables A and B, and you do a select on table A and join on table B:

    SELECT a.*, b.* FROM TABLE_A a JOIN TABLE_B b USING (some_id);

If table A has columns &#39;a\_id&#39;, &#39;name&#39;, and &#39;some\_id&#39;, and table B has &#39;b\_id&#39;, &#39;name&#39;, and &#39;some\_id&#39;, the query will return columns &#39;a\_id&#39;, &#39;name&#39;, &#39;some\_id&#39;, &#39;b\_id&#39;, &#39;name&#39;, &#39;some\_id&#39;. Is there any way to prefix the column names of table B without listing every column individually? The equivalent of this:

    SELECT a.*, b.b_id as &#39;b.b_id&#39;, b.name as &#39;b.name&#39;, b.some_id as &#39;b.some_id&#39;
    FROM TABLE_A a JOIN TABLE_B b USING (some_id);

But, as mentioned, without listing every column, so something like:

    SELECT a.*, b.* as &#39;b.*&#39;
    FROM TABLE_A a JOIN TABLE_B b USING (some_id);

Basically something to say, &quot;prefix every column returned by b.* with &#39;something&#39;&quot;. Is this possible or am I out of luck?

### EDITS
Advice on not using `SELECT *` and so on is valid advice but not relevant in my context, so please stick to the problem at hand -- is it possible to add a prefix (a constant specified in the SQL query) to all the column names of a table in a join?

My ultimate goal is to be able to do a `SELECT *` on two tables with a join, and be able to tell, from the names of the columns I get in my result set, which columns came from table A and which columns came from table B. Again, I don&#39;t want to have to list columns individually, I need to be able to do a `SELECT *`.

SQL select join: is it possible to prefix all columns as &#39;prefix.*&#39;?

Is there a htop/top on Linux where I get to sort processes by network usage?

Network usage top/htop on Linux

<p>Is there a htop/top on Linux where I get to sort processes by network usage?</p>


I have a C++ application, running on Linux, which I&#39;m in the process of optimizing. How can I pinpoint which areas of my code are running slowly?


How can I profile C++ code running on Linux?

I want to execute something in a linux shell under a few different conditions, and be able to output the execution time of each execution.

I know I could write a perl or python script that would do this, but is there a way I can do it in the shell? (which happens to be bash)

Get program execution time in the shell

Does anyone know of a program, a utility, or some programmatic library, preferably for Linux, that takes an unformatted SQL string and pretty prints it?

For example I would like the following

    select * from users where name = &#39;Paul&#39;

be changed to something like this

    select * 
    from users
    where
       name = &#39;Paul&#39;

The exact formatting is not important.
I just need something to take a large SQL string and break it up into something more readable.

SQL string formatter

I want to kill a whole process tree.  What is the best way to do this using any common scripting languages? I am looking for a simple solution.

What&#39;s the best way to send a signal to all members of a process group?

Services default to starting as `root` at boot time on my RHEL box. If I recall correctly, the same is true for other Linux distros which use the init scripts in `/etc/init.d`.

What do you think is the best way to instead have the processes run as a (static) user of my choosing?

The only method I&#39;d arrived at was to use something like:

     su my_user -c &#39;daemon my_cmd &amp;&gt;/dev/null &amp;&#39;

But this seems a bit untidy...

Is there some bit of magic tucked away that provides an easy mechanism to automatically start services as other, non-root users?

**EDIT:** I should have said that the processes I&#39;m starting in this instance are either Python scripts or Java programs. I&#39;d rather not write a native wrapper around them, so unfortunately I&#39;m unable to call [setuid()][1] as [Black][2] suggests.

  [1]: http://linux.die.net/man/2/setuid
  [2]: https://stackoverflow.com/users/25234/black

Best practice to run Linux service as a different user

I am programming a server and it seems like my number of connections is being limited since my bandwidth isn&#39;t being saturated even when I&#39;ve set the number of connections to &quot;unlimited&quot;.

How can I increase or eliminate a maximum number of connections that my Ubuntu Linux box can open at a time? Does the OS limit this, or is it the router or the ISP? Or is it something else?  


Increasing the maximum number of TCP/IP connections in Linux

We are looking for a Wireshark-like tool to use on the iPhone to test a 3rd party application before partnering with the 3rd party.  Any suggestions?

How do you monitor network traffic on the iPhone?

I&#39;ve recently come into a web development position with a company who just lost their server/network admin. Though I was hired for web development, I&#39;m being asked to do some routine maintenance tasks on the server that I&#39;m nonetheless having trouble with, having no background in this sort of stuff. It doesn&#39;t help that we&#39;ve lost all communication with the old network admin.

Here&#39;s the situation. A few dozen faculty members in this section of the university have shared directories on the server (Windows Server 2003, SP 2) such as `\\servername\Jones$`, `\\servername\Smith$`, and `\\servername\Watson$`. My question is this: **Why are the share names appended with dollar signs?** It doesn&#39;t appear to be a technical requirement, nor does it distinguish those folders from other similarly-named folders. **Is this standard style, a requirement of some sort that I&#39;ve failed to understand, or something that I should write off as the product of the last admin&#39;s eccentricity?**

Apologies for the kinda lame question, but I haven&#39;t been able to figure this out, and I&#39;ve been continuing to add new directories with dollar-sign-appended share names because I&#39;m unsure about whether or not it&#39;s actually necessary.

Why are these folders&#39; share names appended with dollar signs?

The socket API is the de-facto standard for TCP/IP and UDP/IP communications (that is, networking code as we know it). However, one of its core functions, `accept()` is a bit magical.

To borrow a semi-formal definition:

&gt; accept() is used on the server side.
&gt; It accepts a received incoming attempt
&gt; to create a new TCP connection from
&gt; the remote client, and creates a new
&gt; socket associated with the socket
&gt; address pair of this connection.

In other words, `accept` returns a new socket through which the server can communicate with the newly connected client. The old socket (on which `accept` was called) stays open, on the same port, listening for new connections.

How does `accept` work? How is it implemented? There&#39;s a lot of confusion on this topic. Many people claim accept opens a new port and you communicate with the client through it. But this obviously isn&#39;t true, as no new port is opened. You actually can communicate through the same port with different clients, but how? When several threads call `recv` on the same port, how does the data know where to go?

I guess it&#39;s something along the lines of the client&#39;s address being associated with a socket descriptor, and whenever data comes through `recv` it&#39;s routed to the correct socket, but I&#39;m not sure.

It&#39;d be great to get a thorough explanation of the inner-workings of this mechanism.




How does the socket API accept() function work?

Is there a command line based way to send pings to each computer in a subnet?
Like

    for(int i = 1; i &lt; 254; i++)
        ping(192.168.1.i);

to enforce arp resolution?

Send a ping to each IP on a subnet

If you call the top command, you get all the running processes. But how can I *limit* the output only *to a certain process name like &quot;java&quot;*?

I&#39;ve tried this 
 **top -l 2 | grep java**
but in this way you get only snapshots and not a continuously updated list. And **top -l 0 | grep java** is not really clear.

Limit the output of the TOP command to a specific process name

    top -c

Top lists all the processes, there are good options to filter the processes by username by using the option -u &lt;username&gt; but I am wondering if there is any easy way to filter the processes based on processname listed under COMMAND column of the top output.

For Example I would want like top -some option -substring of processname and top displays pids only having this substring in its command name


top -c command in linux to filter processes listed based on processname

Htop on my linux machine shows many &quot;processes&quot; after launching one java program/JVM. I do understand that the JVM runs multiple
threads (for the actual program, for garbage collection, etc). 

But how come htop lists them as multiple processes with different pids. What exactly are those processes?

Htop showing multiple java processes with different pids

We have multiple servers in our lab and I tried to determine which one has more resources currently available. I tried to interpret the information htop displays but I&#39;m not 100% understanding all those numbers. 

I have taken a screen shot for each server after issuing htop:


Server #1:

![][1]

Server #2: 

![][2] 

Does server #1 have more memory available than server #2? Should I look at Avg or Mem? Or what other parameter should I look at?

Thanks!


 [1]:http://i.imgur.com/zIEqjOj.jpg
 [2]:http://i.imgur.com/vjEcyzA.jpg

How do I interpret the memory usage information from htop

I would like to quickly find if my process is running by searching its name in htop. I could only find the PID or list all process one by one which not convenient. 

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Network usage top/htop on Linux

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SQL select join: is it possible to prefix all columns as 'prefix.*'?

Why doesn't Python have multiline comments?

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