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Questions tagged [centos]

Questions specific to the CentOS Linux distribution. Use this tag if your question relates to how the CentOS distribution affects your problem; do not use it if you just happen to be using CentOS and your question is about a specific configuration detail or syntax.

184
votes
3answers
927k 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 ...
142
votes
11answers
233k 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 ...
132
votes
2answers
424k 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. ...
125
votes
9answers
466k 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 ...
122
votes
10answers
207k views

How to determine CentOS version?

How do I determine the 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....
107
votes
2answers
190k 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?
88
votes
2answers
144k views

How to install dig on CentOS?

I can't find the dig command on my new CentOS installation. I've tried yum install dig but it say it cannot find the package. How do I install dig on CentOS?
87
votes
2answers
76k views

How to shrink root filesystem without booting a livecd

I find myself needing to rearrange a system's partitions to move data previously under the root filesystem into dedicated mount points. The volumes are all in LVM, so this is relatively easy: create ...
79
votes
2answers
162k 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?
75
votes
2answers
103k views

How do I 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 ...
73
votes
8answers
139k 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 ...
72
votes
2answers
152k views

The name > org.freedesktop.PolicyKit1 was not provided by any .service files

When attempting to launch system-config-users from command line, I get the following warning, and the tool does not open. I'm using CentOS 7 with Mate 1.8.1. WARNING **: Error enumerating actions:...
69
votes
2answers
17k views

Process with weird random name consuming significant network and CPU resources. Is someone hacking me?

In a VM on a cloud provider, I'm seeing a process with weird random name. It consumes significant network and CPU resources. Here's how the process looks like from pstree view: systemd(1)───...
65
votes
5answers
248k 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: ...
64
votes
5answers
118k views

Can't Install build-essential on CentOS

When I run the command: sudo apt-get install build-essential I get the following error message: Reading Package Lists... Done Building Dependency Tree... Done E: Couldn't find package build-...
57
votes
1answer
64k views

Do I need to do something about “Delta RPMs disabled”?

While updating packages on our CentOS server I got the following message: Downloading packages: Delta RPMs disabled because /usr/bin/applydeltarpm not installed. Do I need to do something about that?...
56
votes
2answers
259k 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 ...
51
votes
2answers
40k views

I can't enable Swap space on CentOS 7

So I'm following a tutorial to install OTRS which is Open source Ticket Request System. So in order to install, it requires: 4GB of Swap space. Here's the command I used: [root@ip-10-0-7-41 ~]# df -h ...
50
votes
10answers
120k 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 kernel running. On virtual box I install Centos 6.4 and everything works fine,...
49
votes
8answers
342k 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 ...
48
votes
2answers
129k views

Local installation of .rpms using YUM

I'm asking this question cautiously because I don't want to get this wrong. I have a program_name.rpm file saved locally on my server (CentOS 6.5). I have installed it previously just by navigating ...
48
votes
4answers
159k views

How can I tell what version of apache I'm running?

I know about the phpinfo() way but is there any other way? I'm using CentOS and I can't find the httpd executable to run httpd -v.
48
votes
1answer
80k views

Install PostgreSQL client (psql) only on CentOS

Simple question, but no resources found about this. Is there any way to install only a PostgreSQL client, the terminal-based one, psql, on a CentOS7 system, without installing the complete PostgreSQL ...
47
votes
2answers
89k 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 ...
45
votes
2answers
65k 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 ...
43
votes
3answers
139k views

How to update glibc to 2.14 in CentOS 6.5

I want to install Android NDK on my CentOS 6.5 machine. But when I ran the program, it says it needs glibc 2.14 to be able to run. My CentOS 6.5 only has Glibc 2.12 installed. So I tried to update ...
42
votes
5answers
42k 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 ...
42
votes
4answers
182k 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 ...
41
votes
4answers
57k views

yum Error:rpmdb open failed

I'm trying to run yum update and I'm running this error: rpmdb: PANIC: fatal region error detected; run recovery error: db3 error(-30974) from dbenv->open: DB_RUNRECOVERY: Fatal error, run ...
40
votes
9answers
47k 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 ...
40
votes
5answers
362k 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 ...
36
votes
3answers
323k 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?
36
votes
1answer
88k views

What does “systemctl daemon-reload” do?

I have a service that stopped suddenly. I tried to restart that service but failed and asked to run "systemctl daemon-reload". What it exactly do? What is a "daemon reload?"
35
votes
6answers
93k 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 ...
34
votes
2answers
20k views

What's the difference between /usr/lib/systemd/system and /etc/systemd/system?

Before all the unit files were in /etc/systemd/system/ but now some are showing up in /usr/lib/systemd/system (<- on CentOS, or /lib/systemd/system <- on Debian/Ubuntu), what is the difference ...
33
votes
10answers
272k views

yum update fails: Error: Cannot retrieve repository metadata (repomd.xml) for repository …

I'm using CentOS 6.3. When I try to update my system with yum I have this message: yum update Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile * base: mirrors.ircam.fr * ...
33
votes
2answers
65k views

How do I copy a symbolic link?

I have a symbolic link to a file in one directory. I would like to have that same link in another directory. How do I copy a symbolic link? I tried to cp the symbolic link but this copies the file ...
33
votes
2answers
61k 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 ...
31
votes
7answers
2k 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 && ...
31
votes
7answers
51k 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 ...
31
votes
1answer
129k views

Where to find the Crontab logs in CentOS

First of all I'm using CentOS [root@a etc]# cat system-release CentOS release 6.5 (Final) [root@a cron.daily]# ps -ef | grep cron root 982 1 0 Jun14 ? 00:01:15 crond root ...
30
votes
2answers
4k views

What is the difference between shutdown 18:00 and at 18:00 shutdown?

at 18:00 shutdown now and shutdown 18:00 , are they starting the same service? Do they work the same way?
30
votes
10answers
115k 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 -...
30
votes
2answers
75k views

How to change systemd service timeout value?

In the company I am working now there is a legacy service and its init script is using old SysvInit, but is running over systemd (CentOS 7). Because there's a lot of computation, this service takes ...
29
votes
1answer
65k 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 ...
29
votes
4answers
81k views

How to avoid “yum lock” hassle?

I often encounter the "Another app is currently holding the yum lock; waiting for it to exit..." message when trying to install an app and I have to kill yum manually. How can I avoid that? Is there ...
28
votes
5answers
84k views

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

I am trying to retrieve memory used(RAM) in percentage using Linux commands. My cpanel shows Memory Used which I need to display on a particular webpage. From forums, I found out that correct memory ...
26
votes
2answers
65k views

Couldn't find postgresql.conf & pg_hba.conf files in my postgresql installation

Following all the instructions from UNIXMEN, installed postgresql-9.4 in CentOS 6.4. Everything went well, started the service and could access pgsql screen. But when I try to configure the phpPgAdmin,...
25
votes
7answers
141k 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 ...
24
votes
2answers
123k views

How to modify iptables rules via editing a file rather than interacting via command line?

In the history, i would simply edit a file and then reboot the whole server. i would clone the line that had port 22 open change it to 80 and then save the file.. and reboot the whole system so ...