55
votes
8answers
68k views

How do I find the UUID of a filesystem

I'm running Ubuntu, and want to find out the UUID of a particular filesystem (not partition). I know I can use e2label /dev/sda1 to find out the filesystem label, but there doesn't seem to be a ...
55
votes
5answers
100k views

How to start/stop/restart launchd services from the command line?

How do I restart, say for example my httpd or afpd, running any Mac OS X >= 10.5 (Leopard-), without having to use the GUI and go to System Preferences -> Sharing and unchecking/checking "Web ...
55
votes
2answers
344k views

How to check if a port is blocked on a Windows machine?

On the Windows platform, what native options to I have to check if a port (3306, for example) on my local machine (as in localhost), is being blocked?
55
votes
19answers
8k views

Best Practise and Solutions for Sharing Passwords [closed]

We have various passwords that need to be known to more than one person in our company. For example, the admin password to our internet routers, the password for our web-host, and also a few "non-IT" ...
55
votes
13answers
84k views

Windows 2008: WinSXS directory growing uncontrollably, blocking server

I run a (remotely hosted) virtual Server with Windows 2008 Server for a client. Initially, it had 10 GB of space. During the course of a few weeks - during which nothing was done on the machine ...
55
votes
2answers
12k views

Why is it so difficult to upgrade between major versions of Red Hat and CentOS?

"Can we upgrade our existing production EL5 servers to EL6?" A simple-sounding request from two customers with completely different environments prompted my usual best-practices answer of "yes, but ...
54
votes
5answers
7k views

I accidentaly forbid SSH connection to a remote server… What's next?

Let's say it again, we all make mistakes, and I have just made one. A brief history: I was doing some stuff on a VPS (Debian) I'm renting, when I noticed some strange behaviour. Using the netstat ...
54
votes
13answers
143k views

Using wget to recursively download whole FTP directories

I want to copy all of the files and folders from one host to another. The files on the old host sit at /var/www/html and I only have FTP access to that server, and I can't TAR all the files. Regular ...
54
votes
14answers
21k views

GIT as a backup tool

On a server, install git cd / git init git add . git commit -a -m "Yes, this is server" Then get /.git/ to point to a network drive (SAN, NFS, Samba whatever) or different disk. Use a cron job ...
54
votes
6answers
194k views

How can I read pcap files in a friendly format?

a simple cat on the pcap file looks terrible: $cat tcp_dump.pcap ?ò????YVJ? JJ ?@@.?E<??@@ ?CA??qe?U????иh? .Ceh?YVJ?? JJ ?@@.?E<??@@ ...
54
votes
4answers
27k views

How do I edit git's history to correct an incorrect email address/name [closed]

When I started using git I just did a git init and started calling add and commit. Now I am starting to pay attention and I can see that my commits are showing up as cowens@localmachine, rather than ...
54
votes
9answers
76k views

What's the best way to move c:\users to d:\users under vista/W7 [closed]

I just installed Windows 7 RC1 and want to move c:\users to d:\users. What's the best way to do this? Due to the fact that Windows 7 creates a reserved partition that is mounted as C: in the ...
54
votes
14answers
2k views

Is UPS worthwhile for non-production equipment? [closed]

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 ...
54
votes
4answers
158k views

How can I port forward with iptables?

I want connections coming in on ppp0 on port 8001 to route to 192.168.1.200 on eth0 on port 8080 I've got these two rules -A PREROUTING -p tcp -m tcp --dport 8001 -j DNAT --to-destination ...
54
votes
8answers
56k views

Is a wildcard CNAME DNS record valid?

I know it's valid to have a DNS A record that's a wildcard (e.g. *.mysite.com). Is it possible/valid/advised to have a wildcard CNAME record?
54
votes
1answer
3k views

Can't enter the letter 'e' over ssh [duplicate]

Right now I am experiencing some very, very weird behaviour on a Ubuntu 14.04.2 LTS server I am managing. Connecting to the server over ssh either from cygwin(mintty) or a terminal on a Linux ...
53
votes
8answers
3k views

What are the advantages of tape drives?

IBM still develop and sell tape drives today. The capacity of them seems to be on a par with today's hard drives, but the search time and transfer rate are both significantly lower than that of hard ...
52
votes
10answers
14k views

How to [politely?] tell software vendor they don't know what they're talking about

Not a technical question, but a valid one nonetheless. Scenario: HP ProLiant DL380 Gen 8 with 2 x 8-core Xeon E5-2667 CPUs and 256GB RAM running ESXi 5.5. Eight VMs for a given vendor's system. ...
52
votes
17answers
11k views

Do you skip a rack unit between servers?

It seems like there's a lot of disagreement in mindsets when it comes to installing rackmount servers. There have been threads discussing cable arms and other rackmount accessories, but I'm curious: ...
52
votes
5answers
45k views

“POSSIBLE BREAK-IN ATTEMPT!” in /var/log/secure — what does this mean?

I've got a CentOS 5.x box running on a VPS platform. My VPS host misinterpreted a support inquiry I had about connectivity and effectively flushed some iptables rules. This resulted in ssh listening ...
52
votes
2answers
3k views

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 ...
52
votes
18answers
54k views

Why hasn't rsync caught on in the Windows world? [closed]

It seems that rsync is the de-facto standard for efficient file backup and sync in Unix/Linux. Does anyone have any thoughts on why it wouldn't have caught on in the Windows world? Why hasn't it ...
52
votes
6answers
14k views

Puppet vs Chef, pro and contra from users and use cases [closed]

I already googled and read the "to-puppet-or-to-chef-that-is-the-question" article. I'm interested in use cases, real world implementations in which people had choosen one or the other on real ...
52
votes
3answers
15k views

How to reload screenrc without restarting screen?

After modified screenrc, how to see the changes without restarting screen?
52
votes
16answers
52k views

Is FreeNAS reliable?

FreeNAS seems like a great product with a full checklist of features, even iSCSI. But how reliable is it? There are a few scary stories about lost data, for example here. Here is another example. If ...
52
votes
2answers
14k views

Colors in bash after piping through less?

When I have dircolors defined life is full of... color. When I pipe ls through less to scroll around I lose the colors. Any suggestions?
52
votes
3answers
23k views

How to re-order windows, change the scroll shortcut, and modify the status bar contents in GNU Screen?

I learned to use gnu-screen and have been using it for the past several weeks. I got a grip of the basics now, and would be very helpful if I get these queries clarified: How do I rename / reorder / ...
52
votes
6answers
7k views

What should NOT be managed by puppet?

I'm learning my way through configuration management in general and using puppet to implement it in particular, and I'm wondering what aspects of a system, if any, should not be managed with puppet? ...
51
votes
8answers
30k views

How to create a UUID in bash?

In Java i can create a new random UUID with UUID uuid = UUID.randomUUID(); I now need to do the same within a bash script. Is there a command or library I could use?
51
votes
7answers
114k views

How do you restart php-fpm?

I need to reload my php.ini and there's nothing in the help dialog about restarting it.
51
votes
12answers
5k views

What should I pay attention to when I'm buying a network switch?

Since I'm not a hardware expert, I don't know what features make a network switch a good network switch. What should I pay attention, when I'm comparing the different models from different vendors?
51
votes
4answers
71k views

How can I see Time-To-Live (TTL) for a DNS record?

I would like to see the Time-To-Live (TTL) value for a CNAME record. I have access to dig (on Apple Mac OS X), which gives me an answer like this: % dig host.example.gov <*SNIP*> ;; ANSWER ...
51
votes
11answers
226k views

How to start/stop iptables on Ubuntu?

How can I start/stop the iptables service on Ubuntu? I have tried service iptables stop but it is giving "unrecognized service". Why is it doing so? Is there any other method?
51
votes
9answers
115k views

Creating a virtual machine in VirtualBox from a physical one

Is there any way to create a virtual machine that you can use in VirtualBox from a physical installation that you have? For instance, if I have Windows XP installed on a physical computer and want to ...
51
votes
5answers
50k views

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: ...
51
votes
1answer
42k views

How long does it take for DNS records to propagate?

This is a Canonical Question about DNS Propagation How long does it take for an the various types of records to propagate? Do some propagate faster than others? Why does it take time for DNS ...
50
votes
11answers
5k views

Good reasons to keep 32-bit Microsoft Windows desktop OSes

Server software has been 64-bit only for a while now (Since Server 2008 R2 for Windows, even earlier for Exchange and Sharepoint) and even Ubuntu are pushing you away from 32-bit versions for their ...
50
votes
6answers
41k views

Is X.Y.Z.0 a valid IP address?

Are IP addresses with a 0 in the last octet valid? 10.6.43.0 In my case, I have the the following netmask 255.255.252.0 What about a 0 for the other octets?
50
votes
8answers
71k views

How to tell if a Linux system is big endian or little endian?

I know that certain processors are Big Endian and others are Little Endian. But is there a command, bash script, python script or series of commands that can be used at the command line to determine ...
50
votes
5answers
16k views

How does Ubuntu keep track of the “System restart required” flag in motd?

I have a few Ubuntu servers (8.10, 9.10) that is set to automatically install security updates. Some times these updates requires a restart of the system, and this string is shown in motd: *** System ...
50
votes
4answers
64k views

Running Cron every 2 hours [duplicate]

I have the cron job as shown below, and wanted it to run every 2 hours, but it keeps running every 2 minutes. Can someone tell me where I'm going wrong? * */2 * * * /path-to-script
50
votes
6answers
35k views

What does 'set -e' do, and why might it be considered dangerous?

This question has appeared on a pre-interview quiz and it's making me crazy. Can anyone answer this and put me at ease? The quiz has no reference to a particular shell but the job description is for a ...
50
votes
3answers
113k views

How to sleep in a batch file?

How to pause execution for a while in a Windows batch file between a command and the next one?
50
votes
8answers
2k views

How is fire spread in server rooms and datacenters?

Every now and then I read that a severe fire has happened in some datacenter, lots of equipment has been damaged and customers have gone offline. Now I wonder what is there to support and spread fire? ...
50
votes
1answer
34k views

SSH use only my password, Ignore my ssh key, don't prompt me for a passphrase

This is a question regarding the OpenSSH client on Linux, MacOSX and FreeBSD. Normally, I log into systems using my SSH key. Occasionally, I want my SSH client to ignore my SSH key and use a ...
50
votes
9answers
18k views

Company Password Management [closed]

The topic of personal password management has been covered in great detail time after time. This question is aimed at the business or organization that needs to keep track of many unique passwords for ...
49
votes
7answers
59k views

mysqldump to a tar.gz

Usually after dumping a MySQL database with mysqldump command I immediately tar/gzip the resultant file. I'm looking for a way to do this in one command: So from this: mysqldump dbname -u root -p ...
49
votes
13answers
68k views

What's the best way to check if a volume is mounted in a Bash script?

What's the best way to check if a volume is mounted in a Bash script? What I'd really like is a method that I can use like this: if <something is mounted at /mnt/foo> then <Do some ...
49
votes
5answers
13k views

Monday morning mistake: sudo rm -rf --no-preserve-root /

Here's a an entertaining tragedy. This morning I was doing a bit of maintenance on my production server, when I mistakenly executed the following command: sudo rm -rf --no-preserve-root ...
49
votes
7answers
71k views

Should I use tap or tun for openvpn?

What are the differences between using dev tap and dev tun for openvpn? I know the different modes cannot inter-operate. What is the technical differences, other then just layer 2 vs 3 operation. ...

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