Recently my raspberry pi stopped updating the time when it was turned off/rebooting. I tried changing to time zone with raspi-config to reset the time, but this did not work.
I tried checking the status of ntp with systemctl status ntp and I was told
pi#raspberrypi:/etc/init.d $ systemctl status ntp
● ntp.service
Loaded: not-found (Reason: No such file or directory)
Active: inactive (dead)
I tried installing ntp again with apt-get install ntp but I was told it's already installed.
I tried to restart the service with etc/init.d/ntp restart but I am told that permission is denied. I tried to change the permissions of ntp with chown pi /etc/init.d/ntp but this did not work.
I tried to access ntp with root, using sudo su but I am still told permission is denied, even after chown root /etc/init.d/ntp.
How can I get ntp working again?
The solution was to make ntp executable.
sudo chmod +X /etc/init.d/ntp
Then after a quick reboot everything was back to normal.
Related
I installed Redis server on ubuntu 20.04 with this article step by step. After setting password and other configuration, I run sudo systemctl restart redis.service but changes not be applied. Also, while Redis server was running, I got status with this command sudo systemctl status redis and It said me below message:
What's the problem?!
I searched a lot and found that I should use below commands (using systemctl or service):
with systemctl:
sudo systemctl start redis-server.service to start Redis server
sudo systemctl status redis-server.service to get status of Redis server
sudo systemctl stop redis-server.service to stop Redis server
sudo systemctl restart redis-server.service to apply the changes of config file (sudo nano /etc/redis/redis.conf)
with service:
sudo service redis-server start to start Redis server
sudo service redis-server status to get status
active status:
stop status:
sudo service redis-server stop to stop Redis server
sudo service redis-server restart to apply the changes of config file (sudo nano /etc/redis/redis.conf)
I have a 8GB droplet on digitalocean. We launched our site today and we got intense traffic, we have about 3000 concurrent users.
I tried to raise the amount of concurrent connections (with the advice of apache2buddy) but the suggested MaxRequestWorkers to be 482. Here is the file:
<IfModule mpm_prefork_module>
ServerLimit 482
StartServers 5
MinSpareServers 5
MaxSpareServers 10
MaxRequestWorkers 482
MaxConnectionsPerChild 0
</IfModule>
Apache2 uses mdm_prefork and we have read that it's better if we use mdm_worker.
So i tried to disable mdm_prefork, so that I can enable mdm_worker:
a2dismod mpm_prefork
And I got the following error:
ERROR: The following modules depend on mpm_prefork and need to be disabled first: php7.3
What do I have to do to enable mpm_worker?
I found the possible solution to resolve this on my ubuntu server, dont know whether you are running ubuntu as well on your side, but I feel that the steps that I have taken will be the same for almost all distros with change in 1 step where you need to install a new package and the command for that may change based on the distro that you are using.
so the first step is
$ sudo a2dismod php7.3 mpm_prefork
This will disable the prefork module but before that it will disable the php7.3 module to stop the dependency error from occurring.
Next, we enable the worker module
$ sudo a2enmod mpm_worker
Now, the output would suggest that you restart the apache web-server. So, we do the same
$ sudo systemctl restart apache2
Now, if you go to check your website homepage, it may either throw an error or may load a blank page.
So, how do we resolve that; I scoured multiple community forums and found a solution related to the same but it was for freebsd platform so tried the same on ubuntu with some tweaks required to be made on ubuntu side for the steps to work.
The Solution based on ubuntu OS :
First of all, we enable the proxy, proxy_fcgi and setenvif module followed with a php-fpm package installation corresponding to your php version
$ sudo a2enmod proxy
$ sudo a2enmod proxy_fcgi
$ sudo a2enmod setenvif
$ sudo apt-get install php7.3-fpm -y
the php7.3-fpm installation command is the one where you may need to check the installation steps based on the Distro you are using.
Once, php-fpm service is installed you need to make sure that it gets enabled and then start it, so for that
$ sudo a2enconf php7.3-fpm
$ sudo systemctl enable php7.3-fpm.service
$ sudo systemctl start php7.3-fpm.service
Once, the php-fpm service starts successfully, just restart apache service to make sure all the made changes take effect properly
$ sudo systemctl restart apache2
After these steps are taken, please check/refresh your website homepage and the error page or the blank page will change to the proper website page.
The End-Result; your website has shifted from using prefork module to worker module to handle requests.
Also, if you want to switch to event module instead of worker module; just enable event module in place of worker module in the second step; the one that you will take after disabling php7.3 and prefork module
replace
$ sudo a2enmod mpm_worker
with
$ sudo a2enmod mpm_event
rest all steps after that remain the same irrespective of enabling worker or event module.
These steps helped me switch from prefork module to worker module on my server so hoping it may help you as well as help others who stumble on this issue.
Installed a new vmware player 15.5.1 on win10 pro, using guest linux/unbuntu 18.04 server
Trying to get to install the vmware tools (not sure what options I may have selected when I installed the work station). But the install vmware tools menu is disabled. When I run my VM get the re-install menu that too is disabled.
Tried manual install of vmware tools - but that also did not do the trick:
apt-get install open-vm-tools
apt-get install open-vm-tools-desktapop
systemctl status open-vm-tools
sudo shutdown -r now
ps | grep vmtoolsd
How do I fix this. (just start over with fresh install and all that or try use some other player (!?))
I did not get any response here and could not figure it out - tried many options. (same problem with VirtualBox)
But the good news, at least from cut-n-paste perspective- use alternate client. You can use ssh to login into the machine using your favorite tool - putty or even cmd will work. This actually is a better solution - no need to muck with mouse capture and all that.
So just setup a ssh server
sudo apt update
sudo apt install openssh-server
sudo systemctl status ssh
Active: active (running)
Open firewall
sudo ufw allow ssh
Check IP address
ip a
SSH in with PUtty or Cmd or ..
ssh username#ip_address
You are Done - will work like a charm
Note: This ssh works only from local host as the VM only has Pvt IP. If you can create public IP on VM (that is another arduous adventure - still working on it) - you will be able to remote ssh
I have an issue to install MSSQL on my Linux(Ubuntu 16.04) Server.
I have used the manual from Microsoft but I always fail on the same stage.
Actually, Docker is not an alternative due to Kernal issues.
After:
sudo apt-get install -y mssql-server
I'm supposed to do
sudo /opt/mssql/bin/mssql-conf setup.
This returns after answering all questions:
sqlservr[8383]: sqlservr: The configuration file '/var/opt/mssql/mssql.conf' failed to load (error: The INI file could not be opened. Errno [2] Filename [mssql.conf]).
I can access the config file and it seems to be usable by the script as well.
My Linux skills are not good enough to resolve this issue.
To answer some questions that were raised:
I tried sudo
cat the file returns the content as expected
Try running mssql server as root first (stop the service, run it as root, with /opt/mssql/bin/sqlservr) and see if it works that way. If it does, stop the mssql server and fix the ownership of the mssql dir with sudo chown -R mssql:mssql /var/opt/mssql). More info on this answer.
I created a new non-sudo user(user1) in vagrant(Ubuntu 12.04 OS), and added the insecure public key to the user1 authorised key file. In vagrant file, added the default user as "user1" :
config.ssh.default.username = "user1"
Now vagrant up is failing with following error message:
The following SSH command responded with a non-zero exit status.
Vagrant assumes that this means the command failed!
mkdir -p /vagrant
Stdout from the command:
Stderr from the command:
sudo: no tty present and no askpass program specified
Sorry, try again.
sudo: no tty present and no askpass program specified
Sorry, try again.
sudo: no tty present and no askpass program specified
Sorry, try again.
sudo: 3 incorrect password attempts
But if am setting the sudo user for default user, then vagrant up is successful.
Can anyone help me with the changes I need to do to enable vagrant up for non-sudo users.
Vagrant requires root/sudo permissions on the VM for almost all of it's operations; like configuring the networking, mounting shared folders, running provisioners, etc. So you wouldn't get very useful VM without sudo even if you managed to avoid it.
Note that you only need sudo access on the guest. Vagrant commands itself can (and should) be run as a non-root user on the host.