Questions tagged [ubuntu]

Please don't use this tag just because your system is running Ubuntu. Use it _only_ if your question is somehow specific to Ubuntu only. Note that https://askubuntu.com is specifically dedicated to Ubuntu questions.

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268
votes
16answers
812k views

How do I set my DNS when resolv.conf is being overwritten?

Most of the info I see online says to edit /etc/resolv.conf, but any changes I make there just get overridden. $ cat /etc/resolv.conf # Dynamic resolv.conf(5) file for glibc resolver(3) generated by ...
160
votes
7answers
350k views

delete line in vi

How can I delete a line in VI? Here what I am doing right now: Open up the terminal alt + ctrl + t vi a.txt I move my cursor to the line which I wan to delete, then what key-combination is should ...
144
votes
5answers
184k views

How can I update to a newer version of Git using apt-get?

I've just set up a new machine with Ubuntu Oneiric 11.10 and then run apt-get update apt-get upgrade apt-get install git Now if I run git --version it tells me I have git version 1.7.5.4 but on my ...
138
votes
6answers
397k views

Trying to SSH to local VM Ubuntu with Putty

I have set up a VM of Ubuntu server, have installed OpenSSH, and am now trying to connect to it using Putty. Within Putty, under "Host name", I put "Ubuntu", given this is what I thought it was called ...
102
votes
2answers
367k views

How can I restart the SSH daemon on Ubuntu?

When I type in service sshd restart I get a sshd: unrecognized service error. I do have, in /etc/ssh/ a file sshd_config that I use to set config. I can also putty into the Ubuntu box (it is remote). ...
100
votes
4answers
127k views

How to copy-merge two directories? [duplicate]

I have two directories images and images2 with this structure in Linux: /images/ad /images/fe /images/foo ... and other 4000 folders and the other is like: /images2/ad /images2/fe /...
97
votes
8answers
198k views

File permission issues with shared folders under Virtual Box (Ubuntu Guest, Windows Host)

I am using Ubuntu on Virtual Box and I have a folder which is shared between the host (Windows) and the VM (Ubuntu). When I open any file in the share folder in Ubuntu, I can not change it as its ...
86
votes
3answers
386k views

SSH login with clear text password as a parameter? [duplicate]

I need to login to a user that I've created on a remote host running Ubuntu. I can't use an ssh key because the ssh login will happen from a bash script ran within a server that I won't have access to ...
83
votes
5answers
108k views

Unable to locate package `docker-ce` on a 64bit ubuntu

I'm trying to install Docker on a Ubuntu 64 machine following the official installation guide. Sadly Ubuntu seems it is not able to locate the docker-ce package. Any idea to fix it or at least to ...
82
votes
2answers
113k views

Zip everything in current directory

I'd like to compress and package everything, including files and folders in current directory, into a single ZIP file on Ubuntu. What would be the most convenient command for this (and name of the ...
78
votes
8answers
381k views

“Input/output error” when accessing a directory

I want to list and remove the content of a directory on a removable hard drive. But I have experienced "Input/output error": $ rm pic -R rm: cannot remove `pic/60.jpg': Input/output error rm: cannot ...
73
votes
2answers
94k views

How do I run 32-bit programs on a 64-bit Debian/Ubuntu?

I have a 64-bit (amd64 a.k.a. x86_64) Debian or Ubuntu installation. I need to run 32-bit (i386/i686) programs occasionally, or to compile programs for a 32-bit system. How can I do this with a ...
70
votes
3answers
65k views

What does adduser do that useradd doesn't?

In addition to the more widespread useradd, Debian based systems also contain an additional adduser command which provides a higher level interface for adding users and some related tasks. There are ...
68
votes
7answers
99k views

rsync all files of remote machine over SSH without root user?

I have this command to backup a remote machine. The problem is that I need root rights to read and copy all files. I have no root user enabled for security reasons and use sudo the Ubuntu way. Would I ...
66
votes
18answers
15k views

Root access that can't change root password?

We are having a little problem on a server. We want that some users should be able to do e.g. sudo and become root, but with the restriction that the user can't change root password. That is, a ...
64
votes
7answers
41k views

What is the Linux equivalent to C:\Program Files?

I understand that in Windows as well as Linux and Unix, a program|application|software can be installed in any directory. Also if packages are installed using the distribution's packaging system, it'...
63
votes
6answers
164k views

How can I look up a username by id in linux?

The command id can be used to look up a user's uid, for example: $ id -u ubuntu 1000 Is there a command to lookup up a username from a uid? I realize this can be done by looking at the /etc/passwd ...
63
votes
5answers
159k views

Creating an user without a password

I'm trying to create user without password like this: sudo adduser \ --system \ --shell /bin/bash \ --gecos ‘User for managing of git version control’ \ --group \ --disabled-password \ ...
62
votes
8answers
125k views

keyserver timed out when trying to add a GPG public key

I am trying to add a public key for installing a program with CPG. But I am pretty new to this but every command I found gave me the same error: gpg --keyserver keyserver.ubuntu.com --recv-keys ...
62
votes
7answers
58k views

Long line wrapping in Nano

When editing an authorised_keys file in Nano, I want to wrap long lines so that I can see the end of the lines (i.e tell whose key it is). Essentially I want it to look like the output of cat ...
61
votes
5answers
9k views

After accidentally renaming /usr, how do I rename it back?

I accidentally renamed the directory /usr into /usr_bak. I want to change it back, so I append the path /usr_bak/bin to $PATH to allow the system to find the command sudo. But now sudo mv /usr_bak /...
60
votes
14answers
309k views

mount.nfs: access denied by server while mounting on Ubuntu machines?

I have three machines in production - machineA 10.66.136.129 machineB 10.66.138.181 machineC 10.66.138.183 and all those machines have Ubuntu 12.04 installed in it and I have root access ...
59
votes
6answers
236k views

Shell script fails: Syntax error: “(” unexpected

I've been working on a script that automates setting up a development environment for Raspberry Pi development (step by step details that work are here). The script is linked in that article but ...
57
votes
2answers
120k views

Use shared libraries in /usr/local/lib

I have build some libraries from sources, and the files after make install are in /usr/local/lib For example, in my case I have the file libodb-2.2.so which is in this directory. However when I ...
56
votes
5answers
33k views

What is the difference between ls and l? [duplicate]

I accidentally typed l instead of ls today and found that the command still printed a list of the files in my current directory. Trying l --help brings up the help file for ls suggesting that l is ...
55
votes
2answers
126k views

Ubuntu full list of available services

This question is very similar to this one: List of available services For my specific case, I'm wondering if there is a specific command to show the full list of services under Ubuntu. I did run a ...
53
votes
10answers
27k views

List explicitly installed packages

In Gentoo there is the file /var/lib/portage/world that contains packages that I explicitly installed. By explicit I mean, packages that I choose, not including anything installed by default, or ...
53
votes
8answers
27k views

Run script on screen lock/unlock

I'd like to run a screen if the Gnome session is locked and unlocked. Is there a way that I can intercept this and perform certain actions when the desktop is locked or unlocked?
51
votes
2answers
290k views

How to recover files I deleted now by running rm *? [duplicate]

By mistake I ran rm * on the current directory where I created many c program files. I had been working on these since morning. Now I can't take out again the time that I spent since morning on ...
50
votes
5answers
53k views

How to disable `apt-daily.service` on Ubuntu cloud VM image?

The Ubuntu 16.04 server VM image apparently starts the "apt-daily.service" every 12 hours or so; this service performs various APT-related tasks like refreshing the list of available packages, ...
46
votes
4answers
92k views

VirtualBox: two network interfaces (NAT and host-only ones) in a Debian guest on Ubuntu

I created a Debian VM on VirtualBox with two interfaces: a NAT one (for accessing internet) and a host-only one. However, I do not know how to make both interfaces work at the same time. If I the ...
45
votes
10answers
129k views

Change the Python3 default version in Ubuntu

I am using Ubuntu 16.04 LTS . I have python3 installed. There are two versions installed, python 3.4.3 and python 3.6 . Whenever I use python3 command, it takes python 3.4.3 by default. I want to use ...
43
votes
1answer
13k views

What is $debian_chroot in .bashrc?

What is the debian_chroot variable in my bashrc file? and what is it doing here? PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '
42
votes
3answers
244k views

How to get IP Address using shell script? [duplicate]

Want to get the IP address using Shell script. Without knowing the eth0 or eth1 or eth2 How to get the particular IP address. I am not interest to get localhost address, want to get private IP ...
41
votes
9answers
182k views

Finding files that use the most disk space

Is it possible to list the largest files on my hard drive? I frequently use df -H to display my disk usage, but this only gives the percentage full, GBs remaining, etc. I do a lot of data-intensive ...
41
votes
8answers
50k views

How can I play a sound when script execution is ready?

I am executing every now and then some python scripts which take quite long to execute. I execute them like this: $ time python MyScript.py How can I play a sound as soon as the execution of the ...
41
votes
6answers
42k views

ubuntu server 16.04: cannot get supervisor to start automatically

I installed supervisor on ubuntu server 16.04. $ sudo apt-get install supervisor $ sudo update-rc.d supervisor defaults After rebooting, supervisor didn't get started automatically. Checked the ...
40
votes
3answers
57k views

dpkg cannot find ldconfig/start-stop-daemon in the PATH variable

I was trying to install bsd-mailx utility the package got installed however I am wondering about the error. This is the error I get: Preconfiguring packages ... dpkg: warning: 'ldconfig' not found ...
39
votes
8answers
36k views

Differences between Debian and Ubuntu

I'm getting sick of Ubuntu's seemingly random changes. I'm thinking of switching to Debian permanently. Does anyone know if there's a list of changes between the two distros somewhere? I want to know ...
38
votes
1answer
3k views

How do Ubuntu and Debian manage $HOME for users with sudo privileges?

I have a bash script myhome.sh containing only one line: echo $HOME The script's owner is a user: $ ls -l myhome.sh -rw-rw-r-- 1 user user <date> <time> myhome.sh In Ubuntu 16.04 and ...
36
votes
2answers
21k views

What's the difference between /usr/lib/systemd/system and /etc/systemd/system?

Before all the unit files were in /etc/systemd/system/ but now some are showing up in /usr/lib/systemd/system (<- on CentOS, or /lib/systemd/system <- on Debian/Ubuntu), what is the difference ...
35
votes
7answers
16k views

Force directory to always be in cache

I've been testing out different methods to improve the time it takes to compile my entire c++ project. Currently it takes ~5 minutes. I experimented with distcc, ccache, and others. Recently, I ...
34
votes
12answers
49k views

“mount: / is busy” when trying to mount as read-only so that I can run zerofree

I am trying to run zerofree on Ubuntu 11.04 so that I can compact the VirtualBox vdi image using: VBoxManage modifyhd Ubuntu.vdi --compact In order to run zerofree the disk image has be mounted as ...
34
votes
3answers
23k views

Systemd service - what is `multi-user.target`

I have come across a .service that contains the following: [Install] WantedBy=multi-user.target The original .service file can be found HERE. I am on Ubuntu 16.04LTS.
33
votes
5answers
29k views

How is sudo set to not change $HOME in Ubuntu and how to disable this behavior?

On Ubuntu 12.04, when I sudo -s the $HOME variable is not changed, so if my regular user is regularuser, the situation goes like this: $ cd $ pwd /home/regularuser $ sudo -s # cd # pwd /home/...
33
votes
4answers
29k views

How is Ubuntu based on Debian?

Linux Mint is based on Ubuntu. Ubuntu is based on Debian. Like this, there are several other linux distributions that are based on Ubuntu, Debian, Slackware, etc. What confuses me is what does this ...
32
votes
4answers
18k views

What doesn't need defragmentation? Linux or the ext2 ext3 FS?

Why don't you have to defrag a Linux system? Because it's using the ext2/ext3 file system, or because it's Linux? That's relevant, for I have a double boot system (W7 / Ubuntu) and a common ...
32
votes
8answers
53k views

How can I switch between different audio output hardware using the shell?

I use my laptop with an external monitor which has speakers. When the monitor is attached through HDMI I can switch (using the GUI: Sound Setting --> Hardware) between the normal laptop audio output ...
31
votes
3answers
4k views

Weird service with the name “Carbon” running everyday and occupy 100% CPU

For last few weeks, there has been weird activity in my Ubuntu test server. Please check the below screenshot from htop. Everyday this weird service (which seems like a cryptocurrency mining service) ...
31
votes
2answers
86k views

How to start a service automatically, when Ubuntu starts?

I am using Ubuntu 12.04 and want to have a service starting, when the system is booted normally. As 'service' I understand some code, for example cd my_directory; my_command -host 0.0.0.0 -port ...