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.
16,468
questions
342
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What are the functional differences between .profile .bash_profile and .bashrc
What are the functional differences between the .profile, .bash_profile and .bashrc files?
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votes
5
answers
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Difference in sites-available vs sites-enabled vs conf.d directories (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 ...
- 2,241
199
votes
3
answers
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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 ...
- 2,585
196
votes
14
answers
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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?
- 2,457
148
votes
5
answers
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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 ...
- 1,917
143
votes
3
answers
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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 ...
- 2,334
138
votes
13
answers
302k
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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 ...
- 1,776
136
votes
12
answers
204k
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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. ...
- 2,803
134
votes
3
answers
53k
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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 ...
- 1,707
127
votes
10
answers
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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 ...
- 2,709
123
votes
4
answers
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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. ...
- 1,340
114
votes
8
answers
750k
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?
- 1,253
110
votes
12
answers
787k
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?
neha soni
105
votes
12
answers
272k
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 ...
- 1,051
105
votes
8
answers
156k
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.
...
- 1,422
105
votes
6
answers
128k
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?
- 1,181
104
votes
17
answers
169k
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 ...
- 1,115
98
votes
8
answers
290k
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-...
Yansuck
95
votes
15
answers
221k
views
How to fix PuTTY showing garbled characters? [closed]
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 ...
- 2,430
95
votes
4
answers
56k
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 ...
- 1,343
94
votes
9
answers
87k
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 ...
- 1,635
93
votes
5
answers
51k
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?
- 1,129
90
votes
9
answers
284k
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 ...
- 1,003
88
votes
8
answers
47k
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.
...
- 833
87
votes
5
answers
37k
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 ...
- 1,011
86
votes
9
answers
233k
views
Command line program to test DHCP service
Is there a simple ping-like command to test whether a DHCP service is running on a network? ...on Linux
- 2,840
86
votes
7
answers
100k
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 ...
- 1,661
83
votes
4
answers
45k
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 to ...
- 1,016
83
votes
3
answers
100k
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Ubuntu displays "There is 1 zombie process" upon login
This message appears when I login to my machine:
There is 1 zombie process.
What is it telling me?
Is this anything I should worry about?
If yes, then what should I do, and how?
- 2,598
81
votes
8
answers
251k
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 ...
- 913
81
votes
5
answers
95k
views
Change default directory when I SSH to server
I was wondering if there is a way to change the default directory that I get put into after I SSH into my Ubuntu server.
99% of the time when I'm logging into my server, it is to access files within ...
- 1,265
81
votes
5
answers
158k
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Best location to keep SSL certificates and private keys on Ubuntu servers?
On Ubuntu, it looks like the best place for a private key used to sign a certificate (for use by nginx) is in /etc/ssl/private/
This answer adds that the certificate should go in /etc/ssl/certs/ but ...
- 1,677
78
votes
3
answers
259k
views
Install openssl-dev on Ubuntu server
In order to compile NGinx in need to install openssl and openssl-dev (I'am following a book guide).
So i'am doing this :
sudo apt-get install openssl openssl-dev
But i get an error telling me that ...
- 883
78
votes
9
answers
118k
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 ...
- 1,909
77
votes
11
answers
95k
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
...
- 7,478
77
votes
5
answers
531k
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, ...
- 1,007
76
votes
14
answers
224k
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 ...
- 2,101
76
votes
4
answers
44k
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?
- 13.4k
75
votes
1
answer
52k
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?
- 2,609
74
votes
2
answers
7k
views
How should an IT department choose a standard Linux distribution?
There is a lot of community feeling about what Linux distributions are appropriate for production server environments and which aren't, however, a lot of this feeling seems religiously based, and ...
- 6,938
74
votes
3
answers
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views
What does -qq argument for apt-get mean?
I just received a Vagrantfile and post install bash script. The vagrantfile downloads standard Ubuntu from Ubuntu Cloud but I found something in the bash script.
Few lines of script reads as:
apt-...
user156477
73
votes
5
answers
132k
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?
user56548
73
votes
11
answers
84k
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
...
- 1,171
72
votes
3
answers
150k
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 ...
- 837
70
votes
7
answers
136k
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/...
- 3,553
70
votes
9
answers
202k
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Unknown/unsupported storage engine: InnoDB | MySQL Ubuntu
I recently upgraded from the previous LTS Ubuntu to Precise and now mysql refuses to start. It complains of the following when I attempt to start it:
╰$ sudo service mysql restart
stop: Unknown ...
- 833
69
votes
11
answers
217k
views
How do I check if Log4j is installed on my server?
I have read about security vulnerabilities related to Log4j.
How do I check if Log4j is installed on my server?
My specific servers use Ubuntu 18.04.6 LTS.
I have installed many third-party packages ...
- 881
68
votes
6
answers
106k
views
Straight forward way to run ssh-agent and ssh-add on login via SSH?
I'm trying to have the following commands be auto-executed when I login to my server via ssh:
ssh-agent /bin/bash
ssh-add ~/.ssh/id_rsa
My ssh key has a passphrase and I'm fine with entering it once ...
- 875
66
votes
9
answers
258k
views
Deleting All Partitions From the Command Line
How do you delete all partitions on a device from the command line on Linux (specifically Ubuntu)? I tried looking at fdisk, but it presents an interactive prompt. I'm looking for a single command, ...
- 3,620
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votes
5
answers
100k
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associate name with ip for ssh?
Let's say I just have an ip address for a server and I don't have a domain with it (it's just a database server, so it doesn't need a domain). I don't want to have to remember the ip address every ...
- 1,897