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Questions tagged [ubuntu]

Ubuntu Linux is a Debian derivative that aims to bring Linux mainstream. Questions on this site should generally refer to Ubuntu Server. Note that http://askubuntu.com is specifically dedicated to Ubuntu questions.

134
votes
3answers
63k views

What are the functional differences between .profile .bash_profile and .bashrc

What are the functional differences between the .profile, .bash_profile and .bashrc files?
125
votes
10answers
85k views

Can you run Docker natively on the new Windows 10 (Ubuntu) bash userspace?

My understanding was that the primary limitation of running docker on other OSs was the Linux Network containers that made it possible. (Certainly for Macs). Recently Microsoft announced a beta of a ...
117
votes
1answer
72k views

How do I ask apt-get to skip any interactive post-install configuration steps?

I have a server build script which uses apt-get to install packages. It then puts pre-written configuration files directly in place, so the interactive post-install configuration dialog in packages ...
110
votes
3answers
114k views

How do I auto-start docker containers at system boot?

What is a good way to automatically start docker containers when the system boots up? Is there a preferred way to do this on Ubuntu 14.04? I've used supervisord in the past to auto start web apps. ...
104
votes
17answers
165k views

CentOS vs. Ubuntu [closed]

I had a web server that ran Ubuntu, but the hard drive failed recently and everything was erased. I decided to try CentOS on the machine instead of Ubuntu, since it's based on Red Hat. That ...
96
votes
3answers
26k views

How to remove the “installed manually” flag and revert to “automatically installed” with apt-get?

To compile something, I needed the zlib1g-dev package to be installed so I launched an apt-get install zlib1g-dev. apt-get informed me nicely that the package was already auto-installed because of ...
93
votes
8answers
132k views

How to determine JAVA_HOME on Debian/Ubuntu?

On Ubuntu it is possible to have multiple JVMs at the same time. The default one is selected with update-alternatives. But this does not set the JAVA_HOME environment variable, due to a debian policy. ...
87
votes
8answers
43k views

Heartbleed: how to reliably and portably check the OpenSSL version?

I was looking at a reliable and portable way to check the OpenSSL version on GNU/Linux and other systems, so users can easily discover if they should upgrade their SSL because of the Heartbleed bug. ...
85
votes
11answers
451k views

How to start/stop iptables on Ubuntu?

How can I start/stop the iptables service on Ubuntu? I have tried service iptables stop but it is giving "unrecognized service". Why is it doing so? Is there any other method?
82
votes
10answers
63k views

How to view all ssl certificates in a bundle?

I have a certificate bundle .crt file. doing openssl x509 -in bundle.crt -text -noout only shows the root certificate. how do i see all the other certificates?
82
votes
4answers
61k views

What is the different usages for sites-available vs the conf.d directory for nginx

I have some experience using linux but none using nginx. I have been tasked with researching load-balancing options for an application server. I have used apt-get to install nginx and all seems ...
80
votes
7answers
68k views

GPG does not have enough entropy

I've got a ton of processes running in the background to try and get enough entropy, but I am still failing. **We need to generate a lot of random bytes. It is a good idea to perform some other ...
76
votes
5answers
39k views

Why don't EC2 ubuntu images have swap?

I started a couple servers on EC2 and they don't have swap. Am I doing something wrong or is it that the machines just don't have any?
76
votes
5answers
45k views

Job scheduling using crontab, what will happen when computer is shutdown during that time?

I schedule some tasks using crontab. What will happen if my computer is shutdown or turned off during the time when cron was scheduled to do something? Does each missed cron job run after computer ...
75
votes
5answers
29k views

How does Ubuntu keep track of the “System restart required” flag in motd?

I have a few Ubuntu servers (8.10, 9.10) that is set to automatically install security updates. Some times these updates requires a restart of the system, and this string is shown in motd: *** System ...
75
votes
4answers
85k views

list all packages from a repository in ubuntu / debian

is there a command to see what packages are available from a certain ppa repository?
74
votes
11answers
153k views

How do I get apt-get to ignore some dependencies?

How do I make apt-get ignore some dependencies? For example, I wanted to install mailx so I can use it to send email from cron scripts/report-generating tools. However, installing mailx also installs ...
73
votes
3answers
25k views

How do I reattach to Ubuntu Server's 'do-release-upgrade' process?

I accidentally pressed Ctrl+C during Ubuntu Server's do-release-upgrade process. I'd dropped to a shell to compare a .conf file in /etc/. When I pressed Ctrl-C, it asked whether I wanted to try to ...
72
votes
11answers
74k views

apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for ServerName

I keep getting this warning when I (re)start Apache. * Restarting web server apache2 apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for ServerName ...
69
votes
13answers
122k views

How to fix PuTTY showing garbled characters?

Connecting from a Windows 7 PC via SSH to an Ubuntu server using PuTTY, I get some screen errors: I.e. it: "Double-draws" the selection inside Midnight Commander (MC). Other characters like line ...
69
votes
4answers
34k views

dpkg-reconfigure: unable to re-open stdin: No file or directory

I am building a provisioning script for a ubuntu vagrant vm, on a ubuntu host, both 12.10 64bit When installing the following packages: sudo apt-get -y install php5-xsl graphviz php-pear unison I ...
67
votes
9answers
83k views

What is the debian-sys-maint MySQL user (and more)?

I have been bitten several times by the 'debian-sys-maint' user that is installed by default on the mysql-server packages installed from the Ubuntu repositories. Generally what happens is I pull a ...
62
votes
7answers
171k views

How can I edit the welcome message when ssh start?

I have a vps for my website hosting. It is running a ubuntu server. Every time I logged in my server by ssh, it displays a lengthy welcome message in my terminal. Linux node61.buyvm.net 2.6.18-...
62
votes
6answers
347k views

Which ports do I need to open in the firewall to use NFS?

I'm running Ubuntu 11.10 - setting up NFS to share a directory among many other servers. Which ports are required to be opened on the firewall?
61
votes
2answers
24k views

Automate the installation of postfix on Ubuntu

My system configuration script does an "apt-get install -y postfix". Unfortunately the script is halted when the postfix installer displays a configuration screen. Is there a method to force postfix ...
60
votes
8answers
77k views

Can I hide all server / os info?

I don't want anyone to be able to detect that I'm using NGINX or even Ubuntu from the internet. There are tools out there (such as BuiltWith) which scan servers to detect what tools they're using. ...
60
votes
9answers
169k views

Is there a proper way to clear logs?

I was wondering if there was a proper way to clear logs in general? I'm new to Ubuntu and I'm trying to set up Postfix. The log in question is /var/log/mail.log. I was wondering if there was a ...
59
votes
3answers
32k views

How can I check /dev/xvda1?

On login to EC2 (Ubuntu) instance, I see *** /dev/xvda1 should be checked for errors *** I can't fsck /dev/xvda1 because it is mounted, and sudo umount /dev/xvda1 fails because it is in use. lsof ...
58
votes
8answers
141k views

Apache2 config variable is not defined

I installed apache2 on ubuntu 13.10. If I try to restart it using sudo /etc/init.d/apache2 restart I get this message: AH00558: apache2: Could not reliably determine the server's fully qualified ...
58
votes
1answer
3k views

Can't enter the letter 'e' over ssh [duplicate]

Right now I am experiencing some very, very weird behaviour on a Ubuntu 14.04.2 LTS server I am managing. Connecting to the server over ssh either from cygwin(mintty) or a terminal on a Linux machine,...
53
votes
7answers
52k views

Amazon Linux vs. Ubuntu for Amazon EC2 [closed]

I'm setting up my first website on Amazon EC2, and I'm trying to decide which distro to use. I've used Redhat and CentOS in the past, but I have no bias towards any system, I just want to use whatever ...
53
votes
5answers
54k views

How do you use apt-get to only install critical security updates on ubuntu?

How do you use apt-get to only install critical security updates on ubuntu? We'd like to only upgrade packages that need to be upgraded for security reasons, without upgrading all other packages.
53
votes
7answers
39k views

Headless Ubuntu server machine sometimes stuck at GRUB menu

I have Ubuntu 10.10 Server installed on a single-board machine in a semi-embedded environment; no keyboard or screen, just SSH access to it. So it's really frustrating when it occasionally boots up ...
50
votes
5answers
59k views

How can I monitor what logrotate is doing?

How can I monitor what logrotate is doing in Ubuntu? Can the activity of logrotate be monitored?
49
votes
7answers
56k views

protocol version mismatch — is your shell clean?

When following the instructions to do rsync backups given here: http://troy.jdmz.net/rsync/index.html I get the error "protocol version mismatch -- is your shell clean?" I read somewhere that I ...
48
votes
10answers
128k views

df says disk is full, but it is not

On a virtualized server running Ubuntu 10.04, df reports the following: # df -h Filesystem Size Used Avail Use% Mounted on /dev/sda1 7.4G 7.0G 0 100% / none ...
47
votes
3answers
100k views

How do I upgrade from PHP 5.3 to PHP 5.4.6 in Ubuntu?

Is there an easy way out to get the latest PHP? I have tried updating my package but none of it has 5.4.6 yet... if anyone knows on how to do it quickly, can it be shared here? I've tried compiling ...
47
votes
6answers
47k views

Why is ssh agent forwarding not working?

In my own computer, running MacOSX, I have this in ~/.ssh/config Host * ForwardAgent yes Host b1 ForwardAgent yes b1 is a virtual machine running Ubuntu 12.04. I ssh to it like this: ssh pupeno@b1 ...
46
votes
3answers
22k views

What is the difference between PV and HVM virtualization types in ec2?

AWS EC2 offers two types of virtualization of Ubuntu Linux EC2 machines - PV and HVM. PV: HVM: What is the difference between these types?
45
votes
6answers
73k views

what permission to write PID file in /var/run

Ubuntu touch: cannot touch `/var/run/test.pid': Permission denied I am starting start-stop-daemon and like to write the PID file in /var/run start-stop-daemon is run as my-program-user /var/run ...
44
votes
7answers
95k views

How to get e-mail from (failed) cron-jobs in Ubuntu?

I create cron-jobs in Ubuntu by placing the executable in one of /etc/cron.{daily,hourly,monthly,weekly}. There are lots of directories starting with cron: kent@rat:~$ ls -ld /etc/cron* drwxr-xr-x 2 ...
44
votes
10answers
64k views

Docker containers can't resolve DNS on Ubuntu 14.04 Desktop Host

I'm running into a problem with my Docker containers on Ubuntu 14.04 LTS. Docker worked fine for two days, and then suddenly I lost all network connectivity inside my containers. The error output ...
44
votes
2answers
64k views

Ubuntu Server message says packages can be updated, but apt-get does not update any [duplicate]

Possible Duplicate: updates in amazon-ec2 ubuntu 10.04 server When I log into an Ubuntu 10.04.2 LTS server, I see the message: 42 packages can be updated. 18 updates are security updates. But ...
44
votes
1answer
30k views

Why does htop have three load averages?

On htop, it shows three load averages, one bold, one normal, one red. What do they signify?
42
votes
7answers
68k views

How to force MySQL to connect by TCP instead of a Unix socket?

I would like to analyze mysql traffic. Right now, all mysql requests are sent to the MySQL unix socket: unix 2 [ ACC ] STREAM LISTENING 3734388 15304/mysqld /var/run/mysqld/...
42
votes
4answers
283k views

How to properly set permissions for NFS folder? Permission denied on mounting end.

I'm trying to connect to an NFS folder on my dev server. The owner of the folder on the dev server is darren and group darren. When I export and mount it to my Mac using the Disk Utility it mounts, ...
42
votes
2answers
24k views

Damaged /vmlinuz and /initrd.img symbolic links after Kernel uninstall

OS: Ubuntu 8.04 LTS Server Edition We just rolled back an kernel update using the following command: sudo apt-get remove linux-image-2.6.24-24-server The uninstallation was successful, but it had ...
41
votes
4answers
45k views

Can't get bower working - bower ESUDO Cannot be run with sudo

I get the following error when I run bower: bower ESUDO Cannot be run with sudo Thing is, I'm not running bower with sudo. The command I run is: bower install foo or bower search cats I am ...
41
votes
3answers
76k views

Block range of IP Addresses

I am getting bombarded with attempted hacks from China all with similar IPs. How would I block the IP range with something like 116.10.191.* etc. I am running Ubuntu Server 13.10. The current line ...
41
votes
8answers
53k views

Ubuntu Apache: httpd.conf or apache2.conf?

which one of these two files should I use to configure Apache? The httpd.conf is empty, while apache2.conf is not. It confuses me!