Highest scored questions - Page 4

185 votes

8 answers

280k views

Filename length limits on linux?

Are there any filename or path length limits on Linux?

readonly

3,429

asked May 18, 2009 at 17:27

185 votes

16 answers

175k views

Why is DNS failover not recommended?

From reading, it seems like DNS failover is not recommended just because DNS wasn't designed for it. But if you have two webservers on different subnets hosting redundant content, what other methods ...

Lin

2,949

asked Aug 30, 2009 at 17:57

184 votes

61 answers

14k views

Good tools that fit on a thumb drive [closed]

I have been on the lookout lately for some good tools to fill up my flash drive and I thought I would ask the Server Fault community for recommendations on good tools that will fit onto a thumb drive. ...

Community wiki

7 revs, 7 users 56%
Shard

184 votes

31 answers

100k views

How do I prevent accidental rm -rf /*?

I just ran rm -rf /* accidentally, but I meant rm -rf ./* (notice the star after the slash). alias rm='rm -i' and --preserve-root by default didn't save me, so are there any automatic safeguards for ...

Valentin Nemcev

2,035

asked Dec 2, 2011 at 17:09

183 votes

18 answers

1.2m 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.

Galen

1,983

asked Oct 12, 2010 at 1:58

183 votes

12 answers

245k views

What does "Warning: untrusted X11 forwarding setup failed: xauth key data not generated" mean when ssh'ing with -X?

When I use ssh -X on my Mac (running OS X 10.6.7) to connect to my Ubuntu (11.04) box, I get the following warning: Warning: untrusted X11 forwarding setup failed: xauth key data not generated ...

Daryl Spitzer

3,016

asked May 25, 2011 at 22:41

183 votes

5 answers

102k views

What is the difference between Load Balancer and Reverse Proxy?

I'm not clear about the difference between Load Balancer and Reverse Proxy. They both seems having same behavior: distributing incoming requests to backend servers.

Morgan Cheng

2,174

asked Mar 28, 2010 at 8:46

182 votes

2 answers

192k views

How do you answer yes for yum install automatically

In centos how do you answer yes automatically for yum install so that it is an unassisted install?

DiverseAndRemote.com

2,121

asked Oct 25, 2012 at 2:32

181 votes

8 answers

411k views

How do I sleep for a millisecond in bash or ksh

sleep is a very popular command and we can start sleep from 1 second: # wait one second please sleep 1 but what the alternative if I need to wait only 0.1 second or between 0.1 to 1 second ? ...

yael

2,473

asked Jan 15, 2013 at 13:19

180 votes

18 answers

287k views

Disk full, du tells different. How to further investigate?

I have a SCSI disk in a server (hardware Raid 1), 32G, ext3 filesytem. df tells me that the disk is 100% full. If I delete 1G this is correctly shown. However, if I run a du -h -x / then du tells me ...

initall

2,375

asked May 30, 2011 at 12:29

180 votes

8 answers

95k views

Sudo as different user and running screen

Found out today that running screen as a different user that I sudo into won't work! i.e. ssh bob@server # ssh into server as bob sudo su "monitor" - screen # fails: Cannot ...

sdot257

3,069

asked Feb 25, 2010 at 15:07

180 votes

11 answers

112k views

Run an interactive bash subshell with initial commands without returning to the ("super") shell immediately

I want to run a bash subshell, (1) run a few commands, (2) and then remain in that subshell to do as I please. I can do each of these individually: Run command using -c flag: $> bash -c "ls; pwd; ...

SABBATINI Luca

1,801

asked Mar 9, 2012 at 15:12

177 votes

7 answers

357k views

What does Virtual memory size in top mean?

I am running top to monitor my server performance and 2 of my java processes show virtual memory of up to 800MB-1GB. Is that a bad thing? What does virtual memory mean? And oh btw, I have swap of ...

kapso

2,113

asked May 4, 2010 at 15:37

177 votes

5 answers

99k views

What's the difference between authorized_keys and authorized_keys2?

Just wanted a quick summary of the differences between them and why there are two?

Jon

2,131

asked Feb 24, 2010 at 10:57

176 votes

9 answers

222k views

Is it possible to detach a process from its terminal? (Or, "I should have used screen!") [duplicate]

Possible Duplicate: Can I nohup/screen an already-started process? On Unix (specifically, Linux), I've started a job in a regular ssh->bash session. I'd like to leave work soon, but I now realize ...

mike

4,013

asked Jul 1, 2009 at 22:16

176 votes

7 answers

752k 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<??@@ CA??qe?U????еz?...

Tony

4,253

asked Jul 9, 2009 at 21:17

175 votes

11 answers

353k views

Run a .bat file in a scheduled task without a window

I have a scheduled task that starts a batch script that runs robocopy every hour. Every time it runs a window pops up on the desktop with robocopy's output, which I don't really want to see. I ...

Tom Dunham

1,895

asked May 17, 2009 at 9:00

174 votes

9 answers

350k views

Is it possible to generate RSA key without pass phrase?

I'm working with Apache2 and Passenger for a Rails project. I would like to create a self-signed SSL Certificate for testing purposes. sudo openssl rsa -des3 -in server.key -out server.key.new ...

diya

1,893

asked Mar 5, 2012 at 6:28

174 votes

10 answers

303k views

How do I diff two text files in Windows Powershell?

I have two text files and want to find the differences between them using Windows Powershell. Is there something similar to the Unix diff tool available? Or is there another other way I haven't ...

Brian Willis

3,839

asked May 7, 2009 at 3:37

172 votes

5 answers

324k views

How to remove the path with an nginx proxy_pass

I have a running web-application at http://example.com/, and want to "mount" another application, on a separate server on http://example.com/en. Upstream servers and proxy_pass seem to work, but for ...

berkes

2,285

asked Dec 20, 2013 at 15:17

171 votes

9 answers

589k views

Find name of Active Directory domain controller

How can I find out the name/IP address of the AD domain controller on my network?

user18682

2,281

asked Oct 25, 2009 at 14:02

171 votes

10 answers

34k views

How bad is IPv4 address exhaustion really?

For years the press has been writing about the problem that there are now very few IPv4 addresses available. But on the other hand, I'm using a server hosting company which gladly gives out public ...

oz1cz

1,605

asked Jan 28, 2018 at 14:01

170 votes

4 answers

247k views

Getting "Cannot ioctl TUNSETIFF tun: Operation not permitted" when trying to connect to OpenVPN

I'm trying to setup an OpenVPN Access Server in AWS using the market place AMI, but I;m struggling to connect to it. The access server is up and running. I've also added a user with Auto-Login and ...

Stephen Melrose

5,965

asked Nov 26, 2014 at 12:50

169 votes

2 answers

198k views

tar - Remove leading directory components on extraction

How can you extract only the target dir and not the complete dir tree? compress tar cf /var/www_bak/site.tar /var/www/site extract tar xf /var/www/site.tar -C /tmp This will produce: /tmp/var/www/...

clarkk

2,085

asked Nov 11, 2011 at 14:58

169 votes

5 answers

233k views

Force dig to resolve without using cache

I'm wondering if there is a way to query a DNS server and bypass caching (with dig). Often I change a zone on the DNS server and I want to check if it resolves correctly from my workstation. But since ...

Daniel

3,157

asked Mar 21, 2012 at 17:15

169 votes

5 answers

284k views

How to add dependency on a Windows Service AFTER the service is installed

I have a Windows Service that makes use of a SQL Server database. I don't have control over the installation of the service, but would like to add a dependency on the service to ensure that it starts ...

Rick

1,835

asked Jun 12, 2009 at 14:52

168 votes

11 answers

70k views

bash: print stderr in red color

Is there a way to make bash display stderr messages in red color?

kolypto

11.2k

asked Aug 26, 2009 at 21:10

168 votes

3 answers

114k views

Why can't a CNAME record be used at the apex (aka root) of a domain?

This is a Canonical Question about CNAMEs at the apices (or roots) of zones It's relatively common knowledge that CNAME records at the apex of a domain are a taboo practice. Example: example.com. IN ...

Andrew B

33.1k

asked Jul 19, 2014 at 10:53

167 votes

14 answers

565k views

Running a cron job manually and immediately

(I have already read How can I test a new cron script ?.) I have a specific problem (cron job doesn't appear to run, or run properly), but the issue is general: I'd like to debug scripts that are ...

Pistos

3,173

asked Nov 18, 2009 at 13:55

166 votes

10 answers

440k views

GRANT SELECT to all tables in postgresql

Is there a one-liner that grants the SELECT permissions to a new user postgresql? Something that would implement the following pseudo-code: GRANT SELECT ON TABLE * TO my_new_user;

Adam Matan

13.6k

asked Aug 30, 2009 at 14:11

166 votes

4 answers

202k views

Find the location of a systemd unit file service

There are many different places where systemd unit files may be placed. Is there a quick and easy way to ask systemd where it read a service’s declaration from, given just the service name?

Joachim Breitner

3,999

asked May 18, 2015 at 14:56

165 votes

8 answers

132k 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 ...

egorgry

2,911

asked May 19, 2010 at 16:39

165 votes

6 answers

228k views

List of files installed from apt package

How do I get a list of files that were or will-be installed when I apt-get a package? Conversely, can I find what package(s) caused a particular file to be installed?

David Nehme

2,166

asked Dec 23, 2009 at 15:32

164 votes

9 answers

552k views

How to remove empty/blank lines from a file in Unix (including spaces)?

How do I remove empty/blank (including spaces only) lines in a file in Unix/Linux using the command line? contents of file.txt Line:Text 1:<blank> 2:AAA 3:<blank> 4:BBB 5:<blank> 6:...

Michael Ellick Ang

2,159

asked Mar 28, 2011 at 22:14

163 votes

12 answers

333k views

Best practices for setting a cron job for Let's Encrypt (Certbot) renewal?

Is this correct way to set cron for renewal of Let's Encrypt cert in Apache2 ? I use Ubuntu 16.04. @monthly letsencrypt renew && service apache2 reload

user3448600

1,629

asked Jul 19, 2016 at 19:07

162 votes

18 answers

296k 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 ...

Mark Biek

1,947

asked Aug 5, 2009 at 20:16

162 votes

5 answers

33k views

Are SSD drives as reliable as mechanical drives (2013)?

SSD drives have been around for several years now. But the issue of reliability still comes up. I guess this is a follow up from this question posted 4 years ago, and last updated in 2011. It's now ...

hookenz

14.6k

asked May 14, 2013 at 4:11

160 votes

3 answers

993k views

What causes the 'Connection Refused' message?

This is a Canonical Question about Connection Refused We see a lot of questions to the effect When I try to connect to a system I get a message Connection refused Why is this ?

user9517

116k

asked Sep 28, 2015 at 12:13

159 votes

8 answers

164k views

Amazon Cloudfront with S3. Access Denied

We're trying to distribute out S3 buckets via Cloudfront but for some reason the only response is an AccessDenied XML document like the following: <Error> <Code>AccessDenied</Code&...

Jordan Adams

1,691

asked Mar 11, 2014 at 12:32

159 votes

5 answers

354k views

How to check if an RSA public / private key pair match

I have two files, id_rsa and id_rsa.pub. What command can be used to validate if they are a valid pair?

Ryan

6,041

asked Sep 11, 2012 at 16:24

158 votes

5 answers

273k views

How to output variable in nginx log for debugging

I am testing nginx and want to output variables to the log files. How can I do that and which log file will it go (access or error).

lulalala

1,727

asked Jul 4, 2012 at 5:29

158 votes

13 answers

331k views

Is there a global, persistent CMD history?

Sometimes I forget how the exact syntax of a CMD command looks and then I would like to search my own CMD history. Clearly, within the same session, you can browse it with the up and down arrow keys ...

raoulsson

4,823

asked Dec 17, 2009 at 18:06

158 votes

2 answers

58k views

Sometimes PowerShell stops sending output until I press enter. Why?

Periodically I notice PowerShell seems to take forever to finish doing whatever it is I told it to do until it occurs to me to "wake it up" by pressing enter. This is not the fault of any one process ...

Nathan Ridley

2,629

asked Nov 20, 2010 at 0:37

157 votes

9 answers

1.3m views

Command line to list users in a Windows Active Directory group?

Is there a command line way to list all the users in a particular Active Directory group? I can see who is in the group by going to Manage Computer --> Local User / Groups --> Groups and double ...

Flyer

asked Aug 3, 2009 at 17:19

157 votes

6 answers

304k views

How can I debug a docker container initialization?

I had an issue with a container, even though it builds perfectly it does not properly start. The cause is a workaround I've added to the Dockerfile (for having a self-configured /etc/hosts routing) ...

estani

2,171

asked May 19, 2014 at 15:28

156 votes

13 answers

77k views

Are networks now faster than disks?

This is a software design question I used to work on the following rule for speed cache memory > memory > disk > network With each step being 5-10 times the previous step (e.g. cache ...

pm100

1,655

asked Feb 21, 2011 at 23:46

154 votes

19 answers

464k views

How to add a timestamp to bash script log?

I have a constantly running script that I output to a log file: script.sh >> /var/log/logfile I'd like to add a timestamp before each line that is appended to the log. Like: Sat Sep 10 21:33:...

Antonius Bloch

4,780

asked Sep 10, 2011 at 21:35

154 votes

3 answers

74k views

Delete Amazon EC2 terminated instance

I created an Amazon Free tier Usage Account. I launched two amazon ec2 instances using the online tool. After that one instance was created and running while other was pending which quickly shifted to ...

Anubhav Agarwal

1,673

asked May 28, 2012 at 21:57

154 votes

5 answers

135k views

How do I make ssh fail rather than prompt for a password if the public-key authentication fails?

I've got a script that SSHes several servers using public key authentication. One of the servers has stopped letting the script log in due to a configuration issue, which means that the script gets ...

rjmunro

2,331

asked Sep 3, 2009 at 10:58

153 votes

9 answers

365k views

What version of RHEL am I using?

From the shell and without root privileges, how can I determine what Red Hat Enterprise Linux version I'm running? Ideally, I'd like to get both the major and minor release version, for example RHEL ...

Arthur Ulfeldt

3,289

asked Dec 1, 2009 at 1:59

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