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1500 questions
52
votes
4 answers
Linux/Windows/Unix/... file names: Which characters are allowed? Which are unescaped?
Which characters are allowed and which of them must be escaped on the command line in different operating systems?
52
votes
6 answers
CIDR for Dummies
I understand what CIDR is, and what it is used for, but I still can't figure out how to calculate it in my head. Can someone give a "for dummies" type explanation with examples?
Bob
- 2,957
52
votes
5 answers
What's the difference between a Layer 2 & Layer 3 switch
What's the difference between a Layer 2 & Layer 3 switch?
I've always wondered and never needed to know until now.
Jon Rhoades
- 5,047
52
votes
7 answers
Gaining administrator privileges in PowerShell
I only have one account on my Windows Vista machine, and that user has administrative privileges. However, when I try to execute a command within PowerShell to kill a certain process, I'm greeted with an "Access is denied" message. How do I become…
Brian
- 797
52
votes
12 answers
How to record server changes?
So we've all probably had this situation: you debug some problem, only to realize it was caused by a config change you made six months ago, and you can't remember why you did it. So you undo it and fix the problem, and now some other problem comes…
scobi
- 889
52
votes
6 answers
Rsync daemon: is it really useful?
Are there any practical benefits in using rsyncd compared to rsync over ssh? Does it really increase speed, stability, anything?
kolypto
- 11,588
51
votes
3 answers
Change current directory to the batch file directory
I have a bat file on windows that execute a procdump operation. The issue with the batch file is that I need to cd to the batch file directory first before executing the job, or else the script won't work.
How to change to the current batch file…
Graviton
- 2,995
51
votes
5 answers
Force systemd timesyncd to sync time with NTP server immediately
I've configured systemd timesyncd to get it's time from a NTP server:
/etc/systemd/timesyncd.conf > NTP=ca.pool.ntp.org
systemctl restart systemd-timesyncd.service
timedatectl set-ntp true
The status is the following:
$ timedatectl…
manifestor
- 6,699
51
votes
6 answers
What are the pros and cons of having your own UPS attached to your own server hosted in a data center?
According to this comment by Tom O'Connor (slightly edited below):
You can seriously cheese off a datacentre by putting an UPS inside your own rack.
What are the risks to the data center should a customer (somehow) choose to do this?
JonathanDavidArndt
- 1,434
51
votes
4 answers
Linux: set up for remote sysadmin
Every now and then I get the odd request to provide remote support, troubleshooting and/or performance tuning on Linux systems.
Larger companies often already have well established procedures to provide remote access to vendors/suppliers and I only…
HBruijn
- 84,206
- 24
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- 224
51
votes
3 answers
How to show the host/configured/default ssh "configuration"?
According to my ssh_config file...
Configuration data is parsed as follows:
command line options
user-specific file
system-wide file
With that said, (and yes, I know, I could scour man ssh_config AND man ssh, and (hope) for documented…
mralexgray
- 1,491
51
votes
2 answers
nginx split large configuration file
My nginx default configuration file is becoming huge. I'd like to split it to smaller config files, each including only one, maximum 4 locations to each file, so that I can enable/disable them quickly.
Actual file looks like this:
server {
…
oliverjkb
- 644
51
votes
5 answers
On a dual CPU server, is it normal for one CPU to run hotter than the other?
I have a dual Opteron server running Linux with libvirt to host several VMs. The VMs work fine and the server processes OK, but I notice one CPU always runs about 69C (throttles at 70C) and the other runs about 15C.
This doesn't seem normal to me?…
foobarfuzzbizz
- 2,113
51
votes
5 answers
PDU wiring - is this normal (or even safe)?
I removed the side panel of our server rack so I can clean up some of the wiring. Inside I found the PDU was wired like in the picture. Instead of an incoming power cable, there's just 3 uninsulated spade connectors.
Is there any reason for wiring…
Grant
- 18,125
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51
votes
5 answers
Why is tampering with the TTL of IP dangerous?
I've been reading the iptables man-page (light bedtime reading) and i came across the 'TTL' target, but it warns:
Setting or incrementing the TTL field can potentially be very dangerous
and
Don't ever set or increment the value on packets that…
Rob M
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