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1500 questions
467
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
- 6,960
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464
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
- 6,041
- 9
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434
votes
19 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
- 5,329
- 5
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400
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
- 4,472
- 3
- 19
- 17
390
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
- 4,053
- 3
- 16
- 7
380
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
- 4,255
- 3
- 17
- 10
378
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
- 18,954
- 6
- 38
- 55
375
votes
14 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
- 12,504
- 19
- 54
- 73
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
362
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
- 4,031
- 4
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- 27
359
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
- 13,025
- 16
- 59
- 102
352
votes
19 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
- 8,239
- 17
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- 64
337
votes
19 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
- 3,652
- 2
- 17
- 13
336
votes
23 answers
How can I use environment variables in Nginx.conf
I have a docker container running Nginx, that links to another docker container. The host name and IP address of the second container is loaded into the Nginx container as environment variables on startup, but is not know before then (it's dynamic).…
Hugo Rodger-Brown
- 3,507
- 2
- 17
- 12
328
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
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