CentOS is an Enterprise-class Linux Distribution derived from Redhat Enterprise Linux sources freely provided to the public.

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60
votes
11answers
99k views

Is CentOS exactly the same as RHEL?

I'm sure this question has been asked again and again elsewhere (I did not find anything specific to CentOS vs RHEL in SE), but I would still like to ask and confirm a few specific points. I am well ...
40
votes
2answers
72k views

CentOS 6 “Default” Installation Options

Can someone tell me the difference between a Desktop Install, a Basic Server install, and a Minimal Install? During installation, it doesn't give a description and I can't find documentation on it ...
34
votes
2answers
156k views

How to install Desktop Environments on CentOS 7?

I have recently installed CentOS 7(Minimal Install without GUI) and now I want to install a GUI environment in it. How can I install Desktop Environments on previously installed CentOS7 without ...
34
votes
7answers
122k views

How can I fix “cannot find a valid baseurl for repo” errors on CentOS?

I finished installing CentOS 6, but when I tried running yum update I got: [root@centos6test ~]# yum update Loaded plugins: fastestmirror, refresh-packagekit Determining fastest mirrors Could not ...
33
votes
2answers
45k views

In CentOS, what is the difference between yum update and yum upgrade?

What is the difference between yum update and yum upgrade, and when should I use one over the other?
30
votes
7answers
1k views

What's the equivalent to && when writing a bash script?

I apologize in advance if this is a duplicate question. I did make an effort to search/check before asking here. I'm comfortable with writing one-liners like this: foocommand && ...
30
votes
5answers
55k views

How To Install Virtualbox Guest Additions On CentOS via Command Line only

Reading the Virtualbox user manual, I finally got [here], which explains how to install Virtualbox Guest Additions on a Linux guest via Command Line. But it's not clear enough for me (I just started ...
27
votes
1answer
37k views

what is the CentOS equivalent of /var/log/syslog (on Ubuntu)?

On ubuntu this file exists: /var/log/syslog. However the same file does not appear on CentOS Distributions. What is the equivalent file on CentOS?
25
votes
2answers
35k views

How to install dig on CentOS 6?

I can't find the dig command on my new CentOS 6 installation. I've tried yum install dig but it say it cannot find the package. How do I install dig on CentOS 6?
24
votes
5answers
21k views

How can I limit the bandwidth used by a process?

I have a CentOS 5.7 server that will be backing up its files nightly. I am concerned that visitors to the various sites that the server hosts will experience degraded performance while the backup is ...
21
votes
5answers
171k views

How to change hostname on CentOS 6.5?

I can't seem to change the hostname on my CentOS 6.5 host. I am following the instructions I found here: http://www.rackspace.com/knowledge_center/article/centos-hostname-change I set my /etc/hosts ...
21
votes
2answers
17k views

How to colorize output of ls ?

I'm running CentOS in Linux text mode. When I run the command ls /usr/, the output is too hard to read (dark blue on black). How can I change the text coloring?
21
votes
1answer
29k views

BUG: soft lockup - CPU# stuck for x seconds

I've seen a few bug reports and questions (on stackexchange and elsewhere) regarding a nagging "BUG: soft lockup - CPU#<n> stuck for <dt>s!". So far, I haven't found any clue as to what ...
20
votes
6answers
30k views

How to know CentOS version?

How to know version of a CentOS server without access to any graphical interface? I've tried several commands: # cat /proc/version Linux version 2.6.18-128.el5 (mockbuild@hs20-bc1-7.build.redhat.com) ...
20
votes
2answers
20k views

CentOS: List the installed RPMs by date of installation/update?

I'm on a CentOS machine. I updated and installed some packages a few weeks back, but I don't remember the name of every package or the names of every dependency. I used yum. Can I list the packages ...
20
votes
4answers
80k views

Why the default eth0 interface is down by default on CentOS?

I am already a little bit familiar with Linux distros like Debian or Ubuntu (yeah, very similar) but I wanted to try Red Hat based - CentOS 6.2 . I have installed it on my Windows 7 host in virtualBox ...
20
votes
2answers
54k views

ifconfig command not found

I've just installed CentOS7 as a virtual machine on my mac (osx10.9.3 + virtualbox) .Running ifconfig returns command not found. Also running sudo /sbin/ifconfig returns commmand not found. I am root. ...
20
votes
6answers
39k views

CentOS no network interface after installation in VirtualBox

I have Ubuntu 12.10 on which i installed virtual box on which I setup centos 6.4 i386. On Ubuntu I have: 3.5.0-17-generic kernal running. On virtual box I install centos 6.4 and everything works ...
20
votes
5answers
132k views

How to create a FTP user with specific /dir/ access only on a Centos / linux installation

So I'm on a VPS - CentOS Linux installation. I have vsFTPd on the server. I currently have SFTP access to the server via my root user, but am now trying to create a new user with FTP access to a ...
18
votes
7answers
51k views

“Symbolic link not allowed or link target not accessible” / Apache on CentOS 6

I've got a brand new CentOS 6 installation, which has a symlink in the document root to my development files: [root@localhost html]# ls -l total 4 -rwxrwxrwx. 1 root root 0 Sep 18 20:16 index.html ...
18
votes
4answers
3k views

What makes CentOS “enterprisey” compared to “generic” distributions like Ubuntu?

What makes CentOS "enterprisey" compared to "generic" distributions like Ubuntu? When I say "enterprisey" I actually mean "better for server deployments". Just a general question, because I was ...
16
votes
7answers
46k views

CentOS 7 Installation Failed

After hearing the news that CentOS 7 had been published, I decided to install it on my computer. I downloaded the ISO image from the CentOS official website (the one named ...
15
votes
7answers
6k views

Is there a difference of stability between Linux distros?

I've using Debian since 2010 for some home purposes and it has been stable. Is Debian still a good option if I need a server for heavy network, cpu, disk and memory usage? Last month I listened to ...
15
votes
11answers
70k views

Cannot enable network after CentOS 6.3 fresh install

I am trying to perform a fresh CentOS 6.3 installation then run various yum commands such as yum install httpd. The installation runs fine, however I cannot run any network based commands like yum I ...
15
votes
3answers
45k views

How to change the hostname of a linux machine using terminal?

I logged in for the first time, opened terminal, and typed in ‘hostname’. It returned ‘localhost.localdomain.com’. Then I logged as the root user in terminal using the command, ‘su –‘, provided the ...
15
votes
10answers
81k views

How to install CentOS 6 via USB mass storage device?

I want to install CentOS 6.2 on a laptop (Thinkpad R40) which comes without CD/DVD-drive but with USB 2.0 ports. It seems that CentOS does not provide ready-to-use dd-able USB images for ...
15
votes
4answers
59k views

Commands not found: netstat, nmap on CentOS 7

I'm using the following CentOS: $ cat /etc/centos-release CentOS Linux release 7.0.1406 (Core) The commands nmap, netstat and lsof are not found on CentOS7. Why? $ type -a nmap bash: type: nmap: ...
15
votes
1answer
67k views

CentOS - install using yum Apache 2.4

I need Apache 2.4 in CentOS because with Apache 2.2 mod_proxy_wstunnel is not possible. I have tried this, but unfortunately its for RHEL. After installing, I can't execute the Apache 2.4. Can anyone ...
14
votes
5answers
14k views

Limiting processes to not exceed more than 10% of CPU usage

I operate a Linux system which has a lot of users but sometimes an abuse occurs; where a user might run a single process that uses up more than 80% of the CPU/Memory. So is there a way to prevent ...
14
votes
3answers
28k views

How to get memory used(RAM used) using linux command?

I am trying to retrieve memory used(RAM) in percentage using linux command. My cpanel shows Memory Used which I need to display on a particular webpage. From forums, I found out that correct memory ...
14
votes
2answers
13k views

How display log messages from previous boots under CentOS 7?

Executing journalctl under a CentOS 7 system just prints messages generated after the last boot. The command # journalctl --boot=-1 prints Failed to look up boot -1: Cannot assign requested ...
14
votes
2answers
14k views

( /etc/sysconfig/iptables ) “Manual customization of this file is not recommended.” Why?

Editing this file directly /etc/sysconfig/iptables can save me so much headaches so much time and so on... and yet on the very top of the file it says.. Manual customization of this file is not ...
14
votes
1answer
27k views

Setting up network from a “minimal” CentOS 6.4 install [duplicate]

Just installed CentOS 6.4 from a "minimal" ISO. On first boot, I discover that I cannot ping the outside world, yum update, or anything like that: connect: Network is unreachable. In fact, I can't ...
13
votes
2answers
2k views

Is it good to have multiple version of Linux Kernel?

Once, I was installing some kernel patches & something went wrong on a live server where we had hundreds of clients. Only one kernel was there in the system. So, the server was down for some time, ...
13
votes
1answer
40k views

Nslookup: command not found error on RHEL/CentOS 7

During linux installation I selected "minimal" option: When I went to run the nslookup command to look up an IP address I got the error message nslookup: command not found as shown in the example ...
13
votes
1answer
15k views

Does yum's --enablerepo option only enable a repo for the current command?

Does yum's --enablerepo option only enable a repository for the duration of the current command? For example if the enabled setting in /etc/yum.repos.d/remi.repo file is set to 0 (disabled) and I ...
12
votes
10answers
51k views

How to extend CentOS 5 partition on VMware?

I have a CentOS 5 virtual machine and I added 20GB more to disk size. How do I initialize and extend the available space? I'm new to Linux, so what should I do? I tried loading GParted as well, ...
12
votes
2answers
1k views

Accidentally deleted /etc/redhat-release file

I accidentally deleted /etc/redhat-release file. How can I restore or create a new one? I have CentOS Linux release 7.0.1406 (Core).
12
votes
2answers
32k views

I Can't login as root with su command, but I can with SSH

How is it possible that I cannot log in as root by su root or su (I get incorrect password error), but I can log in by ssh root@localhost or ssh root@my_local_IP with the same password? I'm using ...
12
votes
3answers
14k views

Package bash-completion missing from Yum in CentOS 6

I am trying to get tab-completion working in Yum in CentOS 6 (so I can do something like yum install firefo<TAB> and get back firefox), and I have found many tutorials which say to simply do yum ...
12
votes
1answer
5k views

How can I monitor CPU usage by user?

I need to monitor CPU usage by users of two servers' (Ubuntu and CentOS). For example: user1 5% user2 10% ... Is there a tool similar to top or htop that can do that?
12
votes
4answers
807 views

Using real time kernel headers to compile userspace code vs default headers

Per customer requirements, I installed CentOS 5.6 with the default kernel. With this kernel installed, the time.h file includes the #define CLOCK_MONOTONIC. Now, a real-time kernel was installed ...
11
votes
8answers
15k views

jemalloc and other errors making redis on centos 6.4

I am setting up a new, dedicated, centos 6.4 system with redis. I have installed redis many times, but have never hit this issue (and have never been on centos 6.4 before). cd redis-2.6.16 sudo make ...
11
votes
5answers
12k views

How to find out if a system uses SysV, Upstart or Systemd initsystem [duplicate]

Is there a simple way to find out which initsystem is being used e.g by a recent Debian wheezy or Fedora system? I'm aware that Fedora 21 uses systemd initsystem but that is because I read that and ...
11
votes
4answers
6k views

What's the difference between a hard links and copied files?

RHEL 6 My understanding is that hard links include a copy of the original file and that I could delete a hard-linked file in one directory, and it would still exist in the other directory. If ...
11
votes
2answers
3k views

Find out exact installation time of CentOS

I installed CentOS on my laptop about 8 month ago, and I want to know when exactly I installed it , how can I do that in CentOS 6.4 ?
11
votes
2answers
24k views

how do I install the stock centos repositories?

I have a situation where the stock repo files that should exist in /etc/yum.repos.d/ (like centos-base.repo) are not present. I need to get them installed. I am sure this is simple, but after hours of ...
11
votes
4answers
46k views

Increasing Screen Size/Resolution on a VirtualBox Instance of Centos

I have VirtualBox instance of Centos 5. The screen size is quite small (800*600) and I'd like to increase it to 1280*1080. Under the Gnome preferences for "Screen Resolution" I only get the option for ...
11
votes
2answers
19k views

Equivalent of update-grub for RHEL/Fedora/CentOS systems?

In Ubuntu (and I guess in Debian too) there is a system script named update-grub which automatically executes grub-mkconfig -o with the correct path for the grub configuration file. Is there any ...
10
votes
2answers
110k views

Installing git “sudo: apt-get: command not found”

I am trying to install git. I run the following command: sudo apt-get install git-core git-gui git-doc But receive the following error: sudo: apt-get: command not found What should I do?