CentOS is a free (as in beer and speech) GNU/Linux distribution that is community driven and based on source code released from RedHat.

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118
votes
20answers
113k views

How do you install Node.JS on CentOS?

I've found numerous installation instructions for Node.js but they all seem so complicated -- I'm not a super sys admin but I can get around. I have yum on the system, but I didn't find any node.js ...
108
votes
9answers
117k views

When does `cron.daily` run?

When do entries in cron.daily (and .weekly and .hourly) run, and is it configurable? I haven't found a definitive answer to this, and am hoping there is one. I'm running RHEL5 and CentOS 4, but for ...
81
votes
11answers
17k views

How bad is it really to install Linux on one big partition?

We will be running CentOS 7 on our new server. We have 6 x 300GB drives in raid6 internal to the server. (Storage is largely external in the form of a 40TB raid box.) The internal volume comes to ...
66
votes
5answers
59k 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 ...
61
votes
2answers
16k 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 ...
51
votes
4answers
118k views

Adding a directory to $PATH in CentOS?

We just got our new server(s) up and we're running CentOS on them all. After successfully installing Ruby Enterprise Edition, I would now like to add the REE /bin (located at ...
49
votes
7answers
38k views

Allow SFTP but disallow SSH?

I'm starting a very little hosting company for a few friends and little clients, nothing big. I want to give my "clients" the right to manage their files on the server. I hate FTP as it is not secure ...
45
votes
8answers
79k views

How do I update a CentOS server's time from an authoritative time server?

I have CentOS machine and each time I've noticed that the server loses correct time after a while. It is usually behind by several minutes after time passes from having manually set the correct time. ...
42
votes
1answer
11k views

Why are my XFS filesystems suddenly consuming more space and full of sparse files?

I've run XFS filesystems as data/growth partitions for nearly 10 years across various Linux servers. I've noticed a strange phenomenon with recent CentOS/RHEL servers running version 6.2+. Stable ...
36
votes
7answers
28k views

Log all commands run by admins on production servers

It is company policy for admins to login to the servers via a personal username, and then run sudo -i to become root. Upon running sudo -i, sudo will create an environmental variable called ...
34
votes
4answers
70k views

how do you create an ssh key for another user?

I'm trying to create an ssh key for another user. I'm logged in as root. Can I just edit the files generated by ssh-keygen and change root to the user I want?
33
votes
3answers
38k views

My /var/log/btmp file is huge! What should I do?

My /var/log/btmp file is 1.3 GB in size. I've read that the file is "Used to store information about failed login". What does this mean for my server? And can i delete this file?
33
votes
4answers
18k views

How to make a global ~/.vimrc?

Right now, I make everyone do ~/.vimrc and put their settings there. How can I make a global, default .vimrc for new users?
31
votes
2answers
79k views

How do I configure LDAP on Centos 6 for user authentication in the most secure and correct way?

During the last couple of days I have been using a lot of F-words, while browsing Internet for good documentation about how to setup an LDAP-server. So far I have found none, but plenty that are less ...
30
votes
5answers
56k views

How do I change timezone in centos 6.2?

Here is the output of my date command: [root@r1304 ~]# date Wed Apr 18 15:43:28 GST 2012 I want to change the default system timezone to Asia/Dubai. I've followed a tutorial and did this: ln -sf ...
29
votes
4answers
92k views

How to configure vsftpd to work with passive mode

Whenever I install vsftpd on centos, I only setup the jail environment for the users and rest is default configuration of vsftpd. I create user and try to connect with filezila ftp client but I could ...
28
votes
8answers
3k views

Deploying new code live

What's the best practise to deploy new code on a live (e-commerce) site? For now I have stopped apache for +/- 10 seconds when renaming directory public_html_new to public_html and old to ...
27
votes
3answers
2k views

Is it safe to reboot a server open to the internet?

Specifically I have an iptables ruleset defined on a server running CentOS. Am I guaranteed / can I guarantee / how can I guarantee that when networking comes online (either at machine boot, or after ...
26
votes
12answers
144k views

How to find out details about hardware on the Linux machine?

-i.e - how to get a full list of hardware components in command line (on a machine with no window system) Thank you.
26
votes
3answers
30k views

How to install libpq-dev on Centos 5.5

In order to develop one web application based on postgresql, i need to install libpq on my centos. I can install it by "apt-get install libpq-dev" on ubuntu, but i can not install it on centos by ...
26
votes
14answers
9k views

Linux IO monitoring per file?

I am interested in a utility or process for monitoring disk IO per file on CentOS. On Win2008, the resmon utility allows this type of drilldown, but none of the Linux utilities I have found do this ...
26
votes
5answers
10k views

Unusually high dentry cache usage

Problem A CentOS machine with kernel 2.6.32 and 128 GB physical RAM ran into trouble a few days ago. The responsible system administrator tells me that the PHP-FPM application was not responding to ...
25
votes
3answers
13k views

The XFS filesystem is broken in RHEL/CentOS 6.x - What can I do about it?

Recent versions of RHEL/CentOS (EL6) brought some interesting changes to the XFS filesystem I've depended on heavily for over a decade. I spent part of last summer chasing down an XFS sparse file ...
24
votes
2answers
68k views

What does “<service_name> dead but subsys locked” mean?

I'm trying to run memcached on a centos box and it runs for a while, but then ends up in this state: memcached dead but subsys locked netstat shows this: tcp 0 0 :::11211 ...
24
votes
3answers
52k views

How to accurately check if package is installed in yum?

I keep getting answers like: yum list installed | grep bind or rpm -qa | grep bind But that is not accurate as I'm getting a list of few other bind packages like these: ...
23
votes
6answers
71k views

where are the default ulimit values set? (linux, centos)

I have two CentOS 5 servers with nearly identical specs. When I login and do ulimit -u, on one machine I get unlimited, and on the other I get 77824. When I run a cron like: * * * * * ulimit -u ...
23
votes
5answers
109k views

How do I install an rpm that complains about rpmlib(FileDigests) <= 4.6.0-1?

Im trying to install an rpm file on CentOS 5 and Im not sure how to resolve this issues it brings up: $ rpm --install epel-release-6-5.noarch.rpm warning: epel-release-6-5.noarch.rpm: Header V3 ...
22
votes
12answers
35k views

Disable local delivery in Sendmail

I am using Sendmail on a Centos server to send email for PHP scripts, but the problem is that mail is delivered to a local mailbox on the machine rather than what is specified in the MX records for ...
22
votes
3answers
48k views

How do I upgrade to the latest PHP version in CentOS with yum?

I found some blog posts about this, but it's rather lack of descriptions on possible side effects. I could really use some detailed on these steps: How to add a repo that provides PHP 5.4 into yum ...
21
votes
4answers
110k views

Best way to gracefully restart CentOS?

I always used the command: shutdown -r now However, sometimes that causes MySQL issues. What's the most graceful way to restart CentOS? I've seen: reboot and halt How can I gently reboot ...
21
votes
2answers
57k views

Allowing FTP with IPTables

My current scenario involves allowing various rules, but I need ftp to be accessible from anywhere. The OS is Cent 5 and I am using VSFTPD. I can't seem to get the syntax correct. All other rules ...
21
votes
3answers
21k views

CentOS thinks Disk is busy, can't mount or fsck

I'm a longtime user, and first time question submitter. I've spent a full day searching this and many other sites for a solution, but I must resort to requesting assistance to resolve my situation. ...
20
votes
7answers
97k views

What is the value of JAVA_HOME for CentOS?

I have install java through yum on CentOS, however another java programme needs to know what the JAVA_HOME environmental variable is. I know all about setting environmental variables, but what do I ...
19
votes
3answers
5k views

Should I be worried that yum update suddenly wants to update well over 100 packages on my CentOS 6 system?

I get an email alert whenever there's something to update, and typically do them that day. This tends to happen most days. For whatever reason I've had no alerts since 20th July until today (I ...
19
votes
3answers
28k views

How can I get user name by user ID?

In my FTP client I can see files' owner ID (99). How do I find out which user is the owner of these files?
18
votes
3answers
3k views

useradd not encrypting passwords in /etc/shadow

I stumbled accross this problem when trying to create new FTP users for vsftpd. Upon creating a new user with the following command and attempting login with FileZilla, I would get an "incorrect ...
18
votes
10answers
10k views

Shellshock: How do I know if my server is compromised + suspicious files to look out for

Three questions which I hope someone can help answer: How do I know if my server is already compromised due to the Shellshock bug ? If it was compromised, is there a particular folder where I should ...
18
votes
14answers
3k views

Reasons for missing IP info in `last` output on pts logins?

I have five CentOS 6 linux systems at work, and encountered a rather strange issue that only seems to happen with my userid across all the linux systems I have... This is an example of the problem ...
18
votes
2answers
54k views

How can I verify if TLS 1.2 is supported on a remote web server from the RHEL/CentOS shell?

I'm on CentOS 5.9. I'd like to determine from the linux shell if a remote web server specifically supports TLS 1.2 (as opposed to TLS 1.0). Is there an easy way to check for that? I'm not seeing a ...
18
votes
4answers
2k views

Monitoring production server [closed]

Hey all, We have 3 dedicated server, splitted in several VPS using openVZ. We're using munin to monitor the VPS with the production sites, and monit on some one of the VPS to make sure it restarts the ...
17
votes
4answers
14k views

Failed to instal APC via pecl install APC

Hy when i try to install APC via pecl install APC-3.1.5 or even pecl install APC I get following error when the package comes to the make command: running: make /bin/sh ...
17
votes
3answers
38k views

How to list RPM dependencies?

Our production server is running CentOS release 5.2 (Final). How do I see/get/list all the dependencies of an already installed RPM package? For example: SQLite v3.3.6 is already installed in the ...
17
votes
1answer
40k views

MySQL [Warning] IP address could not be resolved

I'm running MySQL5.6.3 on a CentOS 6.1 virtual machine running on Windows XP in VirtualBox. The network card is configured in bridge mode, so my physical & virtual machines share the same ...
17
votes
5answers
36k views

How to backup a full Centos Server?

I switched a few weeks ago from a dedicated server to a VPS. Now that everything is working well on the VPS I would like to shutdown the dedicated server and close my account with the hosting company. ...
17
votes
8answers
80k views

How to send email with my CentOS server?

I just built a modest home server using CentOS 5.5. I want the server to be able to send emails to my Gmail account or other email accounts for various things like cron jobs. Also it would be nice to ...
17
votes
7answers
64k views

How do you re-mount an ext3 fs readwrite after it gets mounted readonly from a disk error?

Its a relatively common problem when something goes wrong in a SAN for ext3 to detect the disk write errors and remount the filesystem read-only. Thats all well and good, only when the SAN is fixed ...
16
votes
4answers
22k views

How do I patch RHEL 4 for the bash vulnerabilities in CVE-2014-6271 and CVE-2014-7169?

A mechanism for remote code execution through Bash has been widely reported yesterday and today (September 24, 2014.) http://seclists.org/oss-sec/2014/q3/650 Reported as CVE-2014-7169 or CVE-2014-6271 ...
16
votes
7answers
22k views

How can I determine what is taking up so much space? [duplicate]

I was using df -h to print out human readable disk usage. I would like to figure out what is taking up so much space. For instance, is there a way to pipe this command so that it prints out files that ...
16
votes
2answers
41k views

Disable the public key check for rpm installation

I want to make a DVD with some useful packages (for example php-common). The only problem is that if I try to install on a computer that's not connected to internet, I can't validate the public key. ...
16
votes
4answers
3k views

/dev/null file became regular file

In our production server suddenly /dev/null became a regular file and due to this sshd service got stopped and not able to login the server. And also we tried to the below steps to configure back to ...