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1500 questions
56
votes
1 answer

What's the difference between sudo su - postgres and sudo -u postgres?

PostgreSQL users peer authentication on unix sockets by default, where the unix user must be the same as the PostgreSQL user. So people frequently use su or sudo to become the postgres superuser. I often see people using constructs like: sudo su -…
Craig Ringer
  • 11,243
56
votes
6 answers

How to automatically close netcat connection after data is sent?

I am executing the following command from a script: echo '{"hostUp": true}' | sudo /usr/local/bin/netcat localhost 8001 However, the netcat client stays open indefinitely. How can I close the connection once this data has been sent?
56
votes
6 answers

Can an SSL certificate be on a single line in a file (no line breaks)?

SSL certificates by default have line breaks after 67 characters. I'm trying to create SSL certificate files using Chef. Essentially I want to create the entire certificate file from a string variable without any line breaks. I've tried this a few…
wrangler
  • 3,170
56
votes
5 answers

Which to install: Apache Worker or Prefork? What are the (dis-)advantages of each?

Based on the descriptions for both the Prefork and Worker MPM, it seems the prefork type is somewhat outdated, but I can't really find a proper comparison of the two types. What i'd like to know: What are the differences between the two…
Aron Rotteveel
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56
votes
7 answers

How to delete EC2 AMI

I know that the command ec2-create-image instance-id will be creating an image of the ec2 instance, creating snapshots file and registering as an AMI. But what is the equivalent command to delete the image which will deleting associated snapshot…
James W.
  • 759
56
votes
1 answer

iptables forwarding between two interface

So I have a linux box with two wireless interfaces, one is a station and the other an AP. wlan0 (station) - Connected to the internet connection wlan1 (AP) - Other clients connect to it. I would like for clients connected to wlan1 to be able to…
broody
  • 673
56
votes
4 answers

Assessing equipment damage following a lightning strike - Should I have planned more?

One of my client's sites received a direct lightning hit last week (coincidentally on Friday the 13th!). I was remote to the site, but working with someone onsite, I discovered a strange pattern of damage. Both internet links were down, most servers…
ewwhite
  • 198,150
56
votes
2 answers

Mysterious visitor to hidden PHP page

On my website, I have a "hidden" page that displays a list of the most recent visitors. There exist no links at all to this single PHP page, and, theoretically, only I know of its existence. I check it many times per day to see what new hits I…
Bill
  • 603
56
votes
5 answers

Create Unix Named Socket from the Command Line

Is there a command similar to mkfifo but for domain sockets?
benmmurphy
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56
votes
14 answers

Is UPS worthwhile for non-production equipment?

Over the years, I've had to throw away a quite a few bits of computing equipment (and the like): Several ADSL routers with odd symptoms (losing wireless connections, losing wired connections, DHCP failures, DNS symptoms etc) Two PVRs spontaneously…
Jon Skeet
  • 4,957
56
votes
6 answers

Cron: Only get errors in emails?

I finally set up a realistic backup schedule on my data through a shell script, which are handled by cron on tight intervals. Unfortunately, I keep getting empty emails each time the CRON has been executed and not only when things go wrong. Is it…
Industrial
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56
votes
11 answers

Is there an equivalent to ssh-copy-id for Windows?

Is there any equivalent or port of ssh-copy-id available for Windows? That is, is there an easy way to transfer SSH keys from a local machine to a remote server under Windows? In case it helps, I'm using Pageant and Kitty (a Putty alternative)…
Matt V.
  • 837
56
votes
2 answers

Difference between Xen PV, Xen KVM and HVM?

I know that Xen is usually better than OpenVZ as the provider cannot oversell in Xen. However, what is the difference between Xen PV, Xen KVM and HVM (I was going through this provider's specs? Which one is better for what purposes and why?…
JP19
56
votes
6 answers

What is better LVM on RAID or RAID on LVM?

I currently have LVM on software RAID, but I'd like to ask you what you think it is better solution, maybe some pros and cons? Edit: It is about software raid on lvm or lvm on software raid. I know than hardware raid is better if we are thinking…
Ency
  • 1,241
56
votes
9 answers

What's the difference between apt-get and aptitude?

I don't get why there are two different programs in a minimal install to install software. Don't they do the same thing? Is there a big difference? I have read everywhere to use aptitude over apt-get but I still don't know the difference
Thomaschaaf
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