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1500 questions
94
votes
5 answers

Why don't EC2 ubuntu images have swap?

I started a couple servers on EC2 and they don't have swap. Am I doing something wrong or is it that the machines just don't have any?
rafamvc
  • 1,139
94
votes
9 answers

GPG does not have enough entropy

I've got a ton of processes running in the background to try and get enough entropy, but I am still failing. **We need to generate a lot of random bytes. It is a good idea to perform some other action (type on the keyboard, move the mouse, utilize…
Joey BagODonuts
  • 1,635
94
votes
6 answers

How do I create user accounts from the Terminal in Mac OS X 10.5?

I would like to be able to create new users in Mac OS X 10.5 remotely after ssh'ing into the machine. How do I do this?
JR Lawhorne
  • 1,231
94
votes
15 answers

How can I set a short timeout with the ping command?

I am trying to write a script that lists all the hosts on my LAN (there a about 20 of them) and writes the ping status next to each host. I have the DHCP leases file, so I have all the IPs (say, 10.0.0.1, 10.0.0.2, etc.), all I need is the ping…
MiniQuark
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93
votes
10 answers

Making `wget` not save the page

I'm using the wget program, but I want it not to save the html file I'm downloading. I want it to be discarded after it is received. How do I do that?
Ram Rachum
  • 5,411
93
votes
9 answers

Linux - Is there a way to prevent/protect a file from being deleted even by root?

I have a very important file which an application in my workplace uses, i need to make sure it is not delete whatsoever, how can I do that?
user256033
93
votes
5 answers

bad ownership or modes for chroot directory component

I created the user MY_USER. Set his home dir to /var/www/RESTRICTED_DIR, which is the path he should be restricted to. Then I edited sshd_config and set: Match user MY_USER ChrootDirectory /var/www/RESTRICTED_DIR Then I restarted ssh. Made…
MultiformeIngegno
  • 1,847
93
votes
8 answers

zcat/gzcat works in linux, not on osx. general linux/osx compatibility

First the specific problem: In linux, I use zcat to list a .zip file. In osx, zcat seems to automatically append .Z to the file name. Various people suggest replacing zcat with gzcat; however, gzcat complains that the file is not in gzip format!…
user23398
  • 1,281
93
votes
4 answers

How to change the name and description of an AWS EC2 security group?

How do you change the name and description of a security group in AWS EC2? My security group is named quick-start-1 (the default) and I want to change it to "HTTP, HTTPS and Limited SSH".
joshua.paling
  • 1,315
93
votes
1 answer

SSH Allow Password For One User, Rest Only Allow Public Keys

Is it possible with ssh to allow passwords from a certain user, but deny using passwords for everybody else? Basically I want to allow password auth for user justin but everybody else must use public keys. PasswordAuthentication no Seems to be…
Justin
  • 5,668
93
votes
9 answers

Is there a proper way to clear logs?

I was wondering if there was a proper way to clear logs in general? I'm new to Ubuntu and I'm trying to set up Postfix. The log in question is /var/log/mail.log. I was wondering if there was a correct way to clear it, rather than me going in it and…
mastofact
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93
votes
6 answers

How do you free up a port being held open by dead process?

A colleague of mine recently ran into a problem where a process that had supposedly died was still bound to a network port, preventing other processes from binding to that port. Specifically, netstat -a -b was reporting that a process named System…
Adam Rosenfield
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  • 7
  • 6
93
votes
9 answers

Command line program to test DHCP service

Is there a simple ping-like command to test whether a DHCP service is running on a network? ...on Linux
pufferfish
  • 3,012
92
votes
6 answers

How to determine the hostname from an IP address in a Windows network?

My LAN has 50 Windows hosts. At the Windows command line I try ping to get the IP address of a running Windows machine. The question is how to get hostname of a specific IP address in the same Windows workgroup? Another question is how to know the…
billyduc
  • 1,637
92
votes
7 answers

How do I make a connection private on Windows Server 2012 R2

After a restart of one of our servers (a Windows Server 2012 R2), all private connections become public and vice versa (this user had the same problem). Stuff like pinging and iSCSI stopped working, and after some investigation it turned out this…
vgru
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