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1500 questions
465
votes
7 answers
Something is burning in the server room; how can I quickly identify what it is?
The other day, we notice a terrible burning smell coming out of the server room. Long story short, it ended up being one of the battery modules that was burning up in the UPS unit, but it took a good couple of hours before we were able to figure it…
Chad Harrison
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458
votes
5 answers
What's the default superuser username/password for postgres after a new install?
I have just installed postgres 8.4 on Ubuntu 9.10 and it has never asked me to create a superuser. Is there a default superuser and its password? If not, how do I create a new one?
Thierry Lam
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399
votes
18 answers
mysqldump throws: Unknown table 'COLUMN_STATISTICS' in information_schema (1109)
Every time I try to make a mysqldump I get the following error:
$> mysqldump --single-transaction --host host -u user -p db > db.sql
mysqldump: Couldn't execute 'SELECT COLUMN_NAME, JSON_EXTRACT(HISTOGRAM,
'$."number-of-buckets-specified"')…
manifestor
- 4,827
- 4
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383
votes
3 answers
How do I change my private key passphrase?
I have an existing public/private key pair. The private key is password protected, and the encryption may be either RSA or DSA. These keys are the kind you generate with ssh-keygen and generally store under ~/.ssh.
I'd like to change the private…
kch
- 4,302
- 3
- 18
- 17
378
votes
20 answers
How to run a server on port 80 as a normal user on Linux?
I have Googled about a solution for quite some time, but couldn't find an answer.
I am on Ubuntu Linux and want to run a server on port 80, but due to security mechanism of Ubuntu, I get the following error:
java.net.BindException: Permission…
Deepak Mittal
- 3,933
- 3
- 16
- 7
376
votes
21 answers
How do you search for backdoors from the previous IT person?
We all know it happens. A bitter old IT guy leaves a backdoor into the system and network in order to have fun with the new guys and show the company how bad things are without him.
I've never personally experienced this. The most I've experienced…
Jason Berg
- 18,854
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373
votes
27 answers
How can I get the size of an Amazon S3 bucket?
I'd like to graph the size (in bytes, and # of items) of an Amazon S3 bucket and am looking for an efficient way to get the data.
The s3cmd tools provide a way to get the total file size using s3cmd du s3://bucket_name, but I'm worried about its…
Garret Heaton
- 4,185
- 3
- 16
- 10
363
votes
5 answers
Anyone else experiencing high rates of Linux server crashes during a leap second day?
*NOTE: if your server still has issues due to confused kernels, and you can't reboot - the simplest solution proposed with gnu date installed on your system is: date -s now. This will reset the kernel's internal "time_was_set" variable and fix the…
Bron Gondwana
- 1,738
- 3
- 12
- 15
353
votes
11 answers
Displaying a remote SSL certificate details using CLI tools
In Chrome, clicking on the green HTTPS lock icon opens a window with the certificate details:
When I tried the same with cURL, I got only some of the information:
$ curl -vvI https://gnupg.org
* Rebuilt URL to: https://gnupg.org/
* Hostname was NOT…
Adam Matan
- 12,044
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353
votes
6 answers
What permissions should my website files/folders have on a Linux webserver?
This is a Canonical Question about File Permissions on a Linux web server.
I have a Linux web server running Apache2 that hosts several websites. Each website has its own folder in…
Nic
- 12,875
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- 58
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340
votes
7 answers
Why is my crontab not working, and how can I troubleshoot it?
This is a Canonical Question about using cron & crontab.
You have been directed here because the community is fairly sure that the answer to your question can be found below. If your question is not answered below then the answers will help you…
Eric Leschinski
- 3,812
- 4
- 19
- 26
333
votes
18 answers
Showing total progress in rsync: is it possible?
I have searched for this option already, but have only found solutions that involve custom patching. The fact that it does not show in --help and no more info can be found probably indicates the answers is 'no', but I'd like to see this…
Aron Rotteveel
- 8,039
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325
votes
18 answers
How do I get the current Unix time in milliseconds in Bash?
How do I get the current Unix time in milliseconds (i.e number of milliseconds since Unix epoch January 1 1970)?
Richard
- 3,532
- 2
- 16
- 13
322
votes
18 answers
Copying a large directory tree locally? cp or rsync?
I have to copy a large directory tree, about 1.8 TB. It's all local. Out of habit I'd use rsync, however I wonder if there's much point, and if I should rather use cp.
I'm worried about permissions and uid/gid, since they have to be preserved in the…
Amandasaurus
- 29,428
- 61
- 176
- 239
318
votes
27 answers
100% uptime for a web application
We received an interesting "requirement" from a client today.
They want 100% uptime with off-site failover on a web application. From our web application's viewpoint, this isn't an issue. It was designed to be able to scale out across multiple…
NotMe
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