To find a hostname in your local network by IP address you can use [`nmblookup` from the samba suite][1]:

    nmblookup -A &lt;ip&gt;

To find a hostname on the internet you could use the `host` program:

    host &lt;ip&gt;

Or you can install `nbtscan` by running:

    sudo apt-get install nbtscan

And use:

    nbtscan &lt;ip&gt;


*Adapted from https://askubuntu.com/questions/205063/command-to-get-the-hostname-of-remote-server-using-ip-address/205067#205067


Update 2018-05-13

You can query a name server with `nslookup`. It works both ways!

    nslookup &lt;IP&gt;
    nslookup &lt;hostname&gt;


  [1]: https://www.samba.org/samba/docs/current/man-html/nmblookup.1.html

In order to use `nslookup`, `host` or `gethostbyname()` then the target&#39;s name will need to be registered with DNS or statically defined in the hosts file on the machine running your program. Yes, you could connect to the target with SSH or some other application and query it directly, but for a generic solution you&#39;ll need some sort of DNS entry for it.

Another simple way I found for using in LAN is
```sh
ssh [username@ip] uname -n
````
If you need to login command line will be 
```sh
sshpass -p &quot;[password]&quot; ssh [username@ip] uname -n
```

Say I have data about 3 trading strategies, each with and without transaction costs.  I want to plot, on the same axes, the time series of each of the 6 variants (3 strategies * 2 trading costs).  I would like the &quot;with transaction cost&quot; lines to be plotted with `alpha=1` and `linewidth=1` while I want the &quot;no transaction costs&quot; to be plotted with `alpha=0.25` and `linewidth=5`.  But I would like the color to be the same for both versions of each strategy. 

I would like something along the lines of:
    
    fig, ax = plt.subplots(1, 1, figsize=(10, 10))
    
    for c in with_transaction_frame.columns:
        ax.plot(with_transaction_frame[c], label=c, alpha=1, linewidth=1)
    
    ****SOME MAGIC GOES HERE TO RESET THE COLOR CYCLE
    
    for c in no_transaction_frame.columns:
        ax.plot(no_transaction_frame[c], label=c, alpha=0.25, linewidth=5)
    
    ax.legend()

What is the appropriate code to put on the indicated line to reset the color cycle so it is &quot;back to the start&quot; when the second loop is invoked?

Reset color cycle in Matplotlib

When I try creating a button and setting a background image in Swift:

    let button   = UIButton.buttonWithType(UIButtonType.System) as UIButton
        button.frame = CGRectMake(100, 100, 100, 100)
        button.setImage(IMAGE, forState: UIControlState.Normal)
        button.addTarget(self, action: &quot;btnTouched:&quot;, forControlEvents: UIControlEvents.TouchUpInside)
        
        self.view.addSubview(button)

I always get an error: &quot;**Cannot convert the expression&#39;s type &#39;Void&#39; to type &#39;UIImage&#39;**&quot;.

Create a button programmatically and set a background image

I&#39;d like to get remote machine/hostname through IP Address. 
I found lots of answer such as nslookup, host, resloveip, etc..
but I still can&#39;t get hostname from my target machine(cent OS, ubuntu etc...)
It seems need to register to DNS server?

I have a machine named **test** and using IP **10.1.27.97**

but I used the method above still can&#39;t not get &quot;**test**&quot;

Does anyone can help me to get the hostname form IP Address?

How to get hostname from IP (Linux)?

I'd like to get remote machine/hostname through IP Address.
I found lots of answer such as nslookup, host, resloveip, etc..
but I still can't get hostname from my target machine(cent OS, ubuntu etc...)
It seems need to register to DNS server?
I have a machine named test and using IP 10.1.27.97
but I used the method above still can't not get "test"
Does anyone can help me to get the hostname form IP Address?

I am trying to automate mysql_secure_installation script with automated response. My code is as follows :
    
    echo &quot;&amp; y y abc abc y y y y&quot; | ./usr/bin/mysql_secure_installation

The actual questions which i am automating are as follows:

    Enter current password for root (enter for none): &lt;enter&gt;
    Set root password? [Y/n] y
    New password: abc
    Re-enter new password: abc
    Remove anonymous users? [Y/n] y
    Disallow root login remotely? [Y/n] y
    Remove test database and access to it? [Y/n] y
    Reload privilege tables now? [Y/n] y

But it gives me an error &quot;Sorry you cannot use an empty password here&quot; but in the screen i used to press the return key for the first question.

Automate mysql_secure_installation with echo command via a shell script

I&#39;m using Ubuntu Linux 12.04 LTS on my local machine. I&#39;ve installed LAMP long ago on my machine. Now I want to enable following PHP extensions:

 1. php_zip
 2. php_xml
 3. php_gd2

For it first I want to check whether these PHP extensions are enabled or not. I searched a lot about how to check the installed/enabled PHP extensions but every time I found how to install these extensions on Ubuntu Linux. So can someone please let me know how should I check the enabled/disabled PHP extensions in Ubuntu Linux 12.04 LTS? Thanks in advance.

How to check which PHP extensions have been enabled/disabled in Ubuntu Linux 12.04 LTS?

I want to pass a password to `ssh` using a bash script (Yes, I know that there are ssh keys that I could use, but this is not what I intend).

I found some solutions that were using `expect` but since it is not a standard bash tool I am wondering if I can do this using pipes.

Can someone explain to me, why exactly something like this:

    echo &quot;password\n&quot; | ssh somehost.com

or

    ssh somehost.com &lt;(echo &quot;password\n&quot;)

doesn&#39;t work? Is there any possibility to make it work? Maybe executing `ssh` as a different process, obtaining its PID and then sending a string directly to it?


Pass a password to ssh in pure bash

I have a short Python script that needs to run at startup - Ubuntu 13.10. I have tried everything I can think of but can&#39;t get it to run. The script:

    #!/usr/bin/python
    import time
    with open(&quot;/home/username/Desktop/startup.txt&quot;, &#39;a&#39;) as f:
    	f.write(str(time.time()) + &quot; It worked!&quot;)
(The actual script is a bit different, as I&#39;m just using this for testing purposes, but you get the idea.)

I&#39;ve tried all of the following, with no luck:

 - Put the command `python startuptest.py` in `crontab`, as `@reboot
   python /home/username/Documents/startuptest.py`, both as the regular user and as `sudo` 
   
 -  Put the command `python /home/username/Documents/startuptest.py` in `/etc/rc.local` 
   
 -  Opened Ubuntu&#39;s Startup Applications and put the command there 
   
 -  Done all of the preceding, putting the command into a shell script
   and calling that shell script instead

Nothing works. I get the feeling I&#39;m missing something simple. Any ideas? (The script runs fine if I just run the command from a terminal.)

Run Python script at startup in Ubuntu

I&#39;m trying to switch user to the tomcat7 user in order to setup SSH certificates.

When I do `su tomcat7`, nothing happens.

`whoami` still ruturns root after doing `su tomcat7`

Doing a `more /etc/passwd`, I get the following result which clearly shows that a tomcat7 user exists:

    root:x:0:0:root:/root:/bin/bash
    daemon:x:1:1:daemon:/usr/sbin:/bin/sh
    bin:x:2:2:bin:/bin:/bin/sh
    sys:x:3:3:sys:/dev:/bin/sh
    sync:x:4:65534:sync:/bin:/bin/sync
    games:x:5:60:games:/usr/games:/bin/sh
    man:x:6:12:man:/var/cache/man:/bin/sh
    lp:x:7:7:lp:/var/spool/lpd:/bin/sh
    mail:x:8:8:mail:/var/mail:/bin/sh
    news:x:9:9:news:/var/spool/news:/bin/sh
    uucp:x:10:10:uucp:/var/spool/uucp:/bin/sh
    proxy:x:13:13:proxy:/bin:/bin/sh
    www-data:x:33:33:www-data:/var/www:/bin/sh
    backup:x:34:34:backup:/var/backups:/bin/sh
    list:x:38:38:Mailing List Manager:/var/list:/bin/sh
    irc:x:39:39:ircd:/var/run/ircd:/bin/sh
    gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/bin/sh
    nobody:x:65534:65534:nobody:/nonexistent:/bin/sh
    libuuid:x:100:101::/var/lib/libuuid:/bin/sh
    messagebus:x:101:104::/var/run/dbus:/bin/false
    colord:x:102:105:colord colour management daemon,,,:/var/lib/colord:/bin/false
    saned:x:103:106::/home/saned:/bin/false
    tomcat7:x:104:107::/usr/share/tomcat7:/bin/false

What I&#39;m trying to work around is this error in Hudson: 

    Command &quot;git fetch -t git@________.co.za:_______/_____________.git +refs/heads/*:refs/remotes/origin/*&quot; returned status code 128: Host key verification failed.

This is my Dockerfile, it takes an existing hudson war file and config that is tarred and builds an image, hudson runs fine, it just can&#39;t access git due to certificates not existing for user tomcat7.


    FROM debian:wheezy
    
    # install java on image
    RUN apt-get update
    RUN apt-get install -y openjdk-7-jdk tomcat7
    
    # install hudson on image
    RUN rm -rf /var/lib/tomcat7/webapps/*
    ADD ./ROOT.tar.gz /var/lib/tomcat7/webapps/
    
    # copy hudson config over to image
    RUN mkdir /usr/share/tomcat7/.hudson
    ADD ./dothudson.tar.gz /usr/share/tomcat7/
    RUN chown -R tomcat7:tomcat7 /usr/share/tomcat7/
    
    # add ssh certificates
    RUN mkdir /root/.ssh
    ADD ssh.tar.gz /root/
    
    # install some dependencies
    RUN apt-get update
    RUN apt-get install --y maven
    RUN apt-get install --y git
    RUN apt-get install --y subversion
    
    # background script
    ADD run.sh /root/run.sh
    RUN chmod +x /root/run.sh
    
    # expose port 8080
    EXPOSE 8080
    
    
    CMD [&quot;/root/run.sh&quot;]


I&#39;m using the latest version of Docker (Docker version 1.0.0, build 63fe64c/1.0.0), is this a bug in Docker or am I missing something in my Dockerfile?

Switching users inside Docker image to a non-root user

Is there a way I can reach my docker containers using names instead of ip addresses?

I&#39;ve heard of pipework and I&#39;ve seen some dns and hostname type options for docker, but I still am unable to piece everything together.

Thank you for your time.

I&#39;m not sure if this is helpful, but this is what I&#39;ve done so far:

- installed docker container host using docker-machine and the vmwarevsphere driver
- started up all the services with docker-compose
- I can reach all of the services from any other machine on the network using IP and port

I&#39;ve added a DNS alias entry to my private network DNS server and it matches the machine name that&#39;s used by docker-machine.  But the machine always picks up a different IP address when it boots and connects to the network.

I&#39;m just lost as to where to tackle this:

- network DNS server
- docker-machine hostname
- docker container hostname
- probably some combination of all of them

I&#39;m probably looking for something similar to this question:

https://stackoverflow.com/questions/27342382/how-can-let-docker-use-my-network-router-to-assign-dhcp-ip-to-containers-easily

Any general direction will be awesome...thanks again!



Content Type	Original Author	Original Content on Stackoverflow
Question	RoyHSIEH	View Question on Stackoverflow
Solution 1 - Linux	HarlemSquirrel	View Answer on Stackoverflow
Solution 2 - Linux	Chris Ryding	View Answer on Stackoverflow
Solution 3 - Linux	Марк Павлов	View Answer on Stackoverflow

How to get hostname from IP (Linux)?

Linux Problem Overview

Linux Solutions

Solution 1 - Linux

Solution 2 - Linux

Solution 3 - Linux

Create a button programmatically and set a background image

Reset color cycle in Matplotlib

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