wilhil's questions

I need to connect to the internet via a TP-Link MA260. After spending hours with usb_modeswitch and other tools, I finally got the device to be recognised as a modem and have the interface wwan0.

I've tried various commands and configs with wvdial, but, I just can't seem to get it to connect.

After reading up many guides, I heard about Network Manager's CLI, so, I installed network manager on to Ubuntu Server.

When I perform nmcli nm it shows

RUNNING         STATE           WIFI-HARDWARE   WIFI       WWAN-HARDWARE   WWAN
running         connected       enabled         enabled    enabled         disabled

I then spent so long looking around the internet, and I stumbled upon this question: How to enable/disable mobile broadband from terminal?, which got me a little further, however, all answers refer to nmcli -t con up id "bla".

No matter what I try, I can't work out how to create "bla", or how I should define the 3G settings, and even when I do find it, I'm not sure what to write.

I found a guide that says that I have to type nmcli con xx, but, edit or add don't seem like valid options and I am stuck.

Can anyone tell me what I need to do to connect?

I have a few Ubuntu boxes that are locked down and used as Kiosks. Whilst we aim to turn them all off safely, the same can not be said for everyone.

The machines use SSDs and there isn't moving hard drives to worry about.

So far, out of about 1000 unexpected shutdowns that have been logged, other than a file scan on a few during startup, there has been no issues sighted and whilst I hope it stays that way, I can't count on it.

There is nothing that needs to persist between sessions and I was wondering if there is anything that can be done to make them more robust?

I have a brand new Ubuntu server installation and go in to aptitude.

Whenever I set a package to remove, the default action is the equivalent of apt-get autoremove. However, it seems that when you go to Actions > Install/remove packages, there is no way to stop your current actions.

going to Actions > Cancel pending actions unmarks Auto on all dependent unneeded packages.

I have even seen that quitting aptitude and going back to install/remove packages has all the same packages listed, but, the auto flag is removed yet again.

This just seems wrong and I was wondering if it is a bug or by design?

If by design, can someone explain to me why someone would want to do this?

I am trying to learn Ubuntu (and Linux in general) on a much deeper level right now and am having a nightmare tracking changes - in particular with the package management system.

Is there any (relatively easy) way I can snapshot the file system and then at a later date compare all changes that have been made since the initial snapshot?

Or, if not file system, can you recommend any technique or program that can help me to achieve this?

Please note that I am looking for an answer that can help me to understand the system deeper and to learn more, I am not looking for how to fix/uninstall. I use virtualisation a lot and can easily rollback if I need to.

If anyone is interested why I am asking this question or if anyone else is tryign to learn...

I installed Ubuntu Server and everything works great - I then wanted to try to install and learn X and how different shells work, so, I typed apt-get install kde, and even though I later did apt-get autoremove kde, there still appears to be hundreds of packages installed that are no longer needed or didn't get removed.

Putting the packages aside, there are bigger system level changes that have occurred such as the system calling startx (I guess) at the startup, but, without KDE, it just freezes... I managed to fix with adding the "text" option to grub, however, considering a default install of Ubuntu without X doesn't have this, I feel like I have cheated and I would like to know how/where X is being invoked.

To jump straight in:

while true; do
    #---  MENU LOGIC HERE, stick response in $MENUEXIT

    #----Deal with responses here

    if [ $S1 == $MENUEXIT ];
    then
            tail -f /path-to-file
    else
            sleep 2
    fi
done

I've tried to keep this as simple as possible, if you need more, let me know.

Basically, I am sticking a menu in a loop, so, if there is incorrect user input or a command finishes, it is meant to re-display the menu.

It worked fine, until I added the tail command.

If I choose the tail option from the menu, the tail command gets launched fine - but, if I hit Ctrl + C, I would like tail to terminate and the menu to be displayed, but it instead both terminates tail AND the script.

I have tried various things such as continues/traps and more, but, I have hit a brick wall and would like some help please?!

I have several Ubuntu servers and there is some behavior that has me curious.

On any newly installed machine (Ubuntu Server 12.04.3 LTS), if I run:

echo "testbla123" | grep -P -o [0-9]*

This will return 123 as expected.

On an older machine (Ubuntu Server 12.04.1 LTS), if I run the same command, I get nothing back, I have to instead run:

echo "testbla123" | grep -P -o "[0-9]*"

After performing an apt-get upgrade, it will perform without quotes around the regex.

Grep is at the same versions on both machines. I tried comparing dependencies before and after the update for some time without much luck.

I was wondering if anyone knows why this happens?

I have been trying for a few days and reading many posts/resources online but am getting nowhere... I have found so many frustratingly unanswered topics such as - http://ubuntuforums.org/showthread.php?t=1572502 or http://ubuntuforums.org/showthread.php?t=1572502 .

Basically, I have a load of switches with 1GB uplinks and we have successfully enabled Link Aggregation between many of the bottlenecks and see 2Gb/s (-overhead) being sent across the links.

I have a server hosting items that constantly is at 100% network utilisation. Long term plan is to move to 10Gb Nics, but, that won't happen for a while.

I have followed every guide I can find about 802.3ad support and I am basically in the same state as this post - http://ubuntuforums.org/showthread.php?t=1572502 ... I have fault tolerance in that I can bring either eth0 or eth1 down and the other will immediately pick up, however, I just can't seem to get more than 944Mb/s to be sent or received.

Can anyone help?

I maintain a few Ubuntu servers and it works great... but, I now have notifications on a few that state there is a new release available and I should run do-release-upgrade.

Since these servers were initially provisioned, I have create a few extra ones that are on the newest version, and, I have noticed quite a few differences.

For example, perhaps I was doing it incorrectly, but, I used to set DNS servers manually in /etc/resolv.conf, but, on the latest version, that file is created/modified automatically and overwritten (and I am still not 100% sure where from).

(Skip to here if you don't want the back story!)

Before I deploy a new version, I really need to know almost every difference and make sure it doesn't break anything... Is there any (official) place to look at that can tell me critical or important differences between the versions?

Are the release notes the only place, or, are there better guides anywhere?

I have a machine that does not have an internet connection and I need to download a few packages to it.

I can use apt-get download xxx to get the package, but, if I ever connect this machine to the internet, will apt-get update / upgrade know what this package is and update it successfully, or will it cause problems in the future?

I have created a file called ntpdate in /etc/cron.hourly

#!/bin/sh
/usr/sbin/ntpdate-debian
date > /tmp/william_tmp
date > /william_tmp
date > ~/william_tmp
echo test

I also did Chmod 755 to this file.

However, I can't tell if the file has run or not!

The file is not created in any of the 3 directories.

If I manually run cd / && run-parts --report /etc/cron.hourly then the files are created and I get the echo.

Can anyone recommend (ideally step by step!) instructions to test that it is working?

When I run ntpdate on its own, I get the following output:

8 Jun 15:47:46 ntpdate[31251]: no servers can be used, exiting

If I run it with the -q ntp.ubuntu.com switch, it seems to query just fine.

I have been hunting through many files and the most relevant one I have found is /etc/default/ntpdate, however, even with NTPDATE_USE_CONF set to no, I just can't understand/see how this error is occurring

Any ideas?

Update--

It appears that ntpdate-debianworks fine and is the actual command that makes use of /etc/default/ntpdate, but this doesn't answer the main question and I still can't find it...

I have just set up a new Ubuntu server and I am going to be doing a lot of networking tests.

During setup, I simply skipped the network step.

I now need to switch between DHCP and an address quite often.

I know I can easily give a port an address via ifconfig eth0 x.x.x.x netmask x.x.x.x, but, is there an alternative that can be used in order to set a port to use DHCP?

If this isn't possible, I am guessing I can default in /etc/network/interfaces to dhcp and then just use up/down or restart networking in order to apply... but, I would much rather use ifconfig.

When installing a new package via apt-get install, I usually just tick yes if it is a program I need/want, but, I read through it, and, I am a little curious as to what the sections actually mean.

1. How does apt-get know what packages are "suggested"?

2. What is the difference between "The following extra packages will be installed" and "The following NEW packages will be installed"?

I disconnect frequently by lag/timeouts or similar from a machine I am connected in to via SSH and I was wondering if my sessions are still active somewhere or if they close/logout after a certain time?

If they are not disconnected, is there a way to connect back in to the session?

(FYI, this is a default install/nothing funky... SSH is in default configuration).

I have an interface eth0, and I wish to give it an extra virtual IP. I achieve this by the following:

ifconfig eth0:0 ip.address.goes.here netmask subnet.address.goes.here

This works fine, however, when I reboot, this is lost.

I have tried editing /etc/network/interfaces to add the following:

auto eth0:0 iface eth0:0 inet static
    address ip.address.goes.here
    netmask subnet.address.goes.here

However, upon rebooting, the static ip for eth0 is loaded fine, but, the eth0:0 virtual IP is not loaded at all.

So, how can I permanently add the eth0:0 virtual IP?

I have a few Ubuntu server boxes set up on ESX, and I changed the IP addresses via SSH. The moment I changed it, it dropped me off of SSH (as expected).

After a restart it works 100% as expected and I can SSH in on the new IP.

However, as much as this works and I know it is a solution, I am trying to learn Linux and would like to restart/bind SSH to the new IP without restarting.

I have attempted /etc/init.d/ssh restart (and stop then start), and services ssh restart (and stop then start), but, nothing seems to work.

However, the weird thing is that from my other server (running on the same ESX box) I can SSH in on the new IP, but, I just can't seem to SSH in from anywhere else until the box is restarted.

I can't work out what I am doing wrong.

Has anyone seen this or can they offer any advice?

(if it changes anything, the IPs I was moving from/to are all internet/public directly routed IPs)

I have an ESX box which I have loaded with two Ubuntu Server machines.

During setup, I chose no additional packages to install as I just wanted a lightweight machine for testing.

The first thing I did was change the root password via sudo passwd

After ESX got on my nerves through lag, I decided to install OpenSSH via apt-get install openssh-server.

It did it's business, and I then opened putty and could connect in to both machines fine. The first time it connected, it asked me to add the ssh key as obviously it did not know it.

Anyway, the second server is working flawlessly, but, the first seems to be giving me trouble.

I was in the middle of typing a sentence when it kicked me off for no reason and when I tried to reconnect, putty gave me a warning that the ssh key had changed and it is potentially dangerous. I attempted to log in anyway and it did not work, just the standard access denied message.

Using the second machine, I SSHed in to the first machine and it worked straight away, I then killed the SSH sessions (and possibly SSH server), I then reconnected via putty and I again received the security warning message, but, it allowed me to log on fine.

... I thought "glitch" and nothing more of it, but, it just happened again!

I really do not understand this and was hoping someone here can help?