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1500 questions
55
votes
4 answers

Start N processes with one systemd service file

I found this systemd service file to start autossh to keep up a ssh tunnel: https://gist.github.com/thomasfr/9707568 [Unit] Description=Keeps a tunnel to 'remote.example.com' open After=network.target [Service] User=autossh # -p [PORT] # -l…
guettli
  • 3,833
55
votes
3 answers

get notification when systemd-monitored service enters failed state

I need to have network messages sent when a systemd service I have crashes or is hung (i.e., enters failed state; I monitor for hung by using WatchdogSec=). I noticed that newer systemd have FailureAction=, but then saw that this doesn't allow…
Display Name
  • 771
55
votes
2 answers

Convert value of an Ansible variable from lower case to upper case

I am working on a playbook to join linux systems to Active Directory. I can't seem to find a way to convert the value of ansible_hostname to uppercase. One of the commands I need to run requires the hostname to be supplied in uppercase.
grahamjgreen
  • 981
55
votes
12 answers

Docker COPY issue - "no such file or directory"

In my Dockerfile I have the following 'COPY" statement: # Copy app code COPY /srv/visitor /srv/visitor It should go without saying that in my host system, under the "/srv/visitor" directory, there is indeed my source code: [root@V12 visitor]# ls…
dlyk1988
  • 1,684
55
votes
3 answers

Isn't Ctrl-Alt-Delete on Linux *really* dangerous?

Is the default Ctrl-Alt-Delete shutdown -r functionality on Linux systems a dangerous feature? Years ago, when I deployed physical systems with attached keyboards and monitors, I'd sometimes modify the /etc/inittab on Red Hat systems to disable the…
ewwhite
  • 198,150
55
votes
6 answers

Why do we still use power supplies on datacenter servers?

Computers mainly need three voltages to work : +12V, +5V and +3,3V, all of them are DC. Why can't we just have a few (for redundancy) big power supply providing these three voltages to the entire datacenter, and servers directly using it ? That…
user186340
55
votes
1 answer

What's the difference between import virtual machines types in Hyper-V?

I was importing a virtual machine to my Hyper-V manager and I got 3 options: Register the virtual machine in place (use the existing unique ID) Restore the virtual machine in place (use the existing unique ID) Copy the virtual machine (create a new…
user214512
  • 561
55
votes
5 answers

HAProxy graceful reload with zero packet loss

I'm running an HAProxy load balancing server to balance load to multiple Apache servers. I need to reload HAProxy at any given time in order to change the load balancing algorithm. This all works fine, except for the fact that I have to reload the…
Conor Taylor
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55
votes
1 answer

nginx: no permission to bind port 8090 but it binds to 80 and 8080

I'm struggling with some strange permission related behavior: when I configure nginx to listen to port 8080 everything works as expected, but when I use any other port I get something like 2014/01/10 09:20:02 [emerg] 30181#0: bind() to 0.0.0.0:8090…
frans
  • 669
55
votes
6 answers

iptables error: unknown option --dport

The command iptables no longer recognizes one of the most commonly used options when defining rules: --dport. I get this error: [root@dragonweyr /home/calyodelphi]# iptables -A INPUT --dport 7777 -j ACCEPT_TCP_UDP iptables v1.4.7: unknown option…
Calyo Delphi
  • 661
55
votes
4 answers

Is there a built-in command-line tool under Windows like wget/curl?

I come from a Linux/Unix background and I have been wondering if Windows has a binary that can download files from the console. I would like to automate a certain process and one of my requirements it to not install much software, but use the…
carlspring
  • 723
55
votes
2 answers

When do DNS queries use TCP instead of UDP?

Possible Duplicate: Is it true that a nameserver have to answer queries over TCP? I know DNS uses UDP for most of its queries, but in what circumstances will it use TCP instead?
pradeepchhetri
  • 2,828
55
votes
16 answers

Stop ssh login from printing motd from the client?

I've got SSH passwordless set up, however it prints the MoTD when it logs in. Is there anyway to stop that happening from the client side? I've tried ssh -q but that doesn't work. I don't want to use ~/.hushlogin nor do I want to change the server…
Amandasaurus
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  • 263
55
votes
9 answers

How can I sniff the traffic of remote machine with wireshark?

I can sniff the traffic of my local pc but I would like to know how to I sniff the traffic of a remote machine by wireshark? When in capture option I select remote interface and enter my remote ip show me error.code(10061). What should I do?
aboutstudy
  • 997
55
votes
1 answer

what s+ S1+ T R+ mean in ps ax ps list

I run this command and got result this but not able to understand the result which node instance should i kill ps ax | grep node 23308 pts/3 S+ 0:00 sudo node index.js 23310 pts/3 Sl+ 0:00 node index.js 23568 pts/1 T 0:00…
Rahul Mehta
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