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1500 questions
361
votes
5 answers

Anyone else experiencing high rates of Linux server crashes during a leap second day?

*NOTE: if your server still has issues due to confused kernels, and you can't reboot - the simplest solution proposed with gnu date installed on your system is: date -s now. This will reset the kernel's internal "time_was_set" variable and fix the…
Bron Gondwana
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361
votes
28 answers

Can I automatically add a new host to known_hosts?

Here's my situation: I'm setting up a test harness that will, from a central client, launch a number of virtual machine instances and then execute commands on them via ssh . The virtual machines will have previously unused hostnames and IP…
gareth_bowles
  • 9,457
353
votes
5 answers

How to send ctrl+alt+del using Remote Desktop?

How can I send ctrl + alt + del to a remote computer over Remote Desktop? For example, if I wanted to change the local admin password on a remote PC using a Remote Desktop connection, it would be helpful to be able to send the ctrl + alt + del key…
T. Marshall
  • 3,633
350
votes
18 answers

Copying a large directory tree locally? cp or rsync?

I have to copy a large directory tree, about 1.8 TB. It's all local. Out of habit I'd use rsync , however I wonder if there's much point, and if I should rather use cp . I'm worried about permissions and uid/gid, since they have to be preserved in…
Amandasaurus
  • 33,989
347
votes
4 answers

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

What are the functional differences between the .profile , .bash_profile and .bashrc files?
lollercoaster
  • 3,635
340
votes
9 answers

Check if port is open or closed on a Linux server?

How can I check if a port is listening on a Linux server?
James Anderson
  • 3,567
330
votes
6 answers

Nginx reverse proxy + URL rewrite

Nginx is running on port 80, and I'm using it to reverse proxy URLs with path /foo to port 3200 this way: location /foo { proxy_pass http://localhost:3200; proxy_redirect off; proxy_set_header Host $host; } This works fine, but I have an application…
jeffreyveon
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324
votes
17 answers

How to properly unban an IP address which Fail2Ban banned?

I'm using Fail2Ban on a server and I'm wondering how to properly unban an IP address. I know I can work with iptables directly, but is there no way to do it with fail2ban-client ? In the manuals it states something like: fail2ban-client get ssh…
psp
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318
votes
27 answers

100% uptime for a web application

We received an interesting "requirement" from a client today. They want 100% uptime with off-site failover on a web application. From our web application's viewpoint, this isn't an issue. It was designed to be able to scale out across multiple…
ChrisLively
  • 3,800
317
votes
14 answers

What's the command-line utility in Windows to do a reverse DNS look-up?

Is there a built-in command line tool that will do reverse DNS look-ups in Windows? I.e., something like <toolname> w.x.y.z => mycomputername I've tried: nslookup : seems to be forward look-up only. host : doesn't exist dig : also doesn't exist. I…
alastairs
  • 3,305
317
votes
8 answers

How to bind MySQL server to more than one IP address?

Is there a secret way to bind MySQL to more than one IP address? As far as I can see the bind-address parameter in the my.cnf does not support more than one IP and you can't have it more than once.
BlaM
  • 3,996
304
votes
4 answers

How do I select which Apache MPM to use?

This is a Canonical Question about selecting the right Apache httpd MPM. I'm a little confused between the different MPMs offered by Apache - 'worker', 'event', 'prefork', etc. What are the major differences between them, and how can I decide which…
Tiffany Walker
  • 6,781
301
votes
4 answers

Why do I need Nginx and something like Gunicorn?

I'm looking for an overly simplified answer to the following question. I'm trying to build a foundational understanding of how Nginx works alongside something like Gunicorn. Do I need both Nginx and something like Gunicorn to deploy Django apps on…
a.m.
  • 3,115
296
votes
5 answers

How to remove an image tag in Docker without removing the image itself?

Let's say I want to tag a Docker image, and make a typo. How do I remove the tag without removing the image itself? Neither the manpages nor the Docker documentation mention removing tags. docker tag 0e5574283393 my-imaj docker tag 0e5574283393…
Mihai
  • 3,416
296
votes
8 answers

command for checking Apache configuration

I'm looking for a command that checks the validity of the config files in Apache server on both Debian and RHEL distros. I need to do this prior to restart, so there will be no downtime.
Sigtran
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