Questions tagged [centos]
CentOS is a free (as in beer and speech) GNU/Linux distribution that is community driven and based on source code released from RedHat.
10,680
questions
255
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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 ...
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votes
2
answers
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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 ...
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136
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4
answers
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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?
- 1,487
132
votes
20
answers
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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 ...
- 2,783
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10
answers
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How to extend an ext4 partition and filesystem?
I have a 400GB disk with a 320GB ext4 partition.
I would like to grow the ext4 partition to use the left space (80GB of free space).
+--------------------------------+--------+
| ext4 ...
- 2,109
128
votes
15
answers
316k
views
Mount CIFS Host is down
I have an issue with a mount point that was previously configured. It shows the folder, but the mount is missing and holds "?" values for size, permissions, etc.
So I tried to remount using cifs and ...
- 1,413
112
votes
9
answers
146k
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 ...
- 1,444
110
votes
10
answers
261k
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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. ...
- 1,257
108
votes
6
answers
118k
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"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 ...
- 12.1k
106
votes
5
answers
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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 the ...
- 1,405
104
votes
17
answers
170k
views
CentOS vs. Ubuntu [closed]
I had a web server that ran Ubuntu, but the hard drive failed recently and everything was erased. I decided to try CentOS on the machine instead of Ubuntu, since it's based on Red Hat. That ...
- 1,115
103
votes
6
answers
314k
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 /usr/lib/ruby-enterprise/...
- 1,281
99
votes
8
answers
251k
views
Show all users and their groups/vice versa
I know I have existing groups and users but I'm not sure about their association. Is there an shell command I can use to list all users or all groups and a command to list all groups/users for a ...
- 1,972
98
votes
7
answers
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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?
- 1,115
98
votes
12
answers
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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 ...
- 1,091
84
votes
2
answers
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How to open port for a specific IP address with firewall-cmd on CentOS? [duplicate]
I would like to open port 4567 for the IP address 1.2.3.4 with the firewall-cmd command on a CentOS 7.1 server.
How can I achieve this, as the documentation I could find was too specific on this?
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82
votes
7
answers
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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 SUDO_USER,...
- 4,386
81
votes
6
answers
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views
Centos 7 save iptables settings
Problem: iptables resets to default settings after server reboot.
I'm trying to set rule like this:
iptables -I INPUT -p tcp --dport 3000 -j ACCEPT
after that I do:
service iptables save
and it ...
- 913
74
votes
2
answers
7k
views
How should an IT department choose a standard Linux distribution?
There is a lot of community feeling about what Linux distributions are appropriate for production server environments and which aren't, however, a lot of this feeling seems religiously based, and ...
- 6,968
74
votes
4
answers
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views
failed to get D-Bus connection: Operation not permitted
I'm trying to list services on my CentOS image running in Docker using
systemctl list-units
but I get this error message:
Failed to get D-Bus connection: Operation not permitted
Any suggestions ...
- 1,157
72
votes
2
answers
34k
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 ...
- 199k
69
votes
9
answers
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views
How can I check from the command line if a reboot is required on RHEL or CentOS?
I'm using CentOS and Red Hat Enterprise Linux on a few machines without the GUI. How can I check if recently installed updates require a reboot? In Ubuntu, I'm used to checking if /var/run/reboot-...
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65
votes
6
answers
22k
views
Server wiped after "yum remove python" [closed]
A disaster just occurred to me after I ran the command yum remove python and now I can't boot the server up anymore.
How it happened: I tried updating some apps via yum on my CentOS 5 VPS and the ...
- 763
65
votes
1
answer
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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 ...
- 199k
64
votes
3
answers
101k
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 "...
- 4,117
62
votes
5
answers
297k
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 ...
- 1,241
54
votes
4
answers
201k
views
Tcpdump on multiple interfaces
I need to capture traffic on a CentOS 5 server which acts as a web proxy with 2 wan interfaces and 1 LAN. In order to troubleshoot a weird proxy problem, I would like to have a capture of a full ...
- 541
54
votes
4
answers
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How do I authenticate with LDAP via the command line?
The LDAP server is hosted on Solaris. The client is CentOS. OpenLDAP/NSLCD/SSH authentication via LDAP work fine, but I am not able to use the ldapsearch commands to debug LDAP issues.
[root@tst-01 ~]...
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53
votes
3
answers
237k
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.
...
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52
votes
6
answers
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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?
- 8,641
51
votes
2
answers
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How can I see the contents of the mail whose ID I get from postfix's mailq command?
I used mailq command and I got a line like for example:
A705238B4C 603953 Wed May 23 11:09:58 [email protected]
So, now I'm wondering is there a way where I can "read" an actual content of the ...
- 877
50
votes
8
answers
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views
ls hangs for a certain directory
There is a particular directory (/var/www), that when I run ls (with or without some options), the command hangs and never completes. There is only about 10-15 files and directories in /var/www. ...
- 8,964
49
votes
6
answers
167k
views
tell yum to ignore a single dependency
I'm trying to install winswitch on CentOs 6. It requires nxagent. But in centos, the package name is nx. Is there a way to tell yum to skip checking the nxagent dependency (I installed nx already)? ...
- 1,127
47
votes
9
answers
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views
Nginx fails to stop and nginx.pid is missing
I want to stop Nginx but it fails like this.
$ sudo service nginx stop
Stopping nginx: [FAILED]
And nginx.conf that defines place of nginx.pid have a line.
#...
- 707
45
votes
5
answers
111k
views
How to shrink /home and add more space on CentOS7
CentOS 7 file system is XFS, And resize2fs doesn't work. I need to shrink /home to 400G and add 100G space to /. What should I do?
# df -h
Filesystem Size Used Avail Use% Mounted on
/...
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45
votes
4
answers
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views
Create new vsftpd user and lock to (specify) home / login directory
I need to periodically give temporary and limited access to various directories on a CentOS linux server that has vsftp installed.
I've created a user using useradd [user_name] and given them a ...
- 1,463
44
votes
9
answers
164k
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 &...
- 441
44
votes
8
answers
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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 ...
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43
votes
2
answers
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CentOS /usr/local/lib system wide $LD_LIBRARY_PATH?
I install custom software in /usr/local/lib. How do I set the PATH and LD_LIBRARY_PATH in CentOS 6 system-wide to use /usr/local/lib. I realize there may be more than one way. What's the simplest and ...
- 1,952
42
votes
13
answers
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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.
- 599
42
votes
3
answers
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Increasing nproc for processes launched by systemd on CentOS 7
I have successfully increased the nofile and nproc value for the local users, but I couldn't find a proper solution for the processes launched by systemd. Adding max_open_files to the MariaDB ...
- 743
41
votes
3
answers
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views
Where does the route to 169.254.0.0 comes from?
Running CentOS 5.4
Why do I have route to 169.254.0.0 although it does not appear in Network > Ethernet Device > Route configuration dialog?
Destination Gateway Genmask Flags ...
- 801
41
votes
5
answers
137k
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 ...
- 1,489
41
votes
1
answer
142k
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 ...
- 513
40
votes
5
answers
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views
Should I be concerned that swap is being used on a host with nearly 40GB of free memory?
I have a production host, below:
The system is using 1GB of swap, while maintaining nearly 40GB of free, unused memory space. Should I be concerned about this, or is it mostly normal?
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votes
4
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views
How to enable PowerTools repository in CentOS 8?
Since I had a lot of trouble finding out how to do this anywhere, I'd like to ask,
how do I enable the PowerTools repository in CentOS 8? (equivalent of CodeReady Linux Builder repo in RHEL 8)
- 503
39
votes
3
answers
111k
views
Finding latest successful logins and failed attempts to a CentOS server
I'm looking for a log file or any service to report the latest login attempts that have failed due to username/password mismatch. Are there any such utilities available for CentOS? (built-in is ...
- 691
39
votes
3
answers
48k
views
SCP transfer only modified files
I'm using below command to transfer files cross server
scp -rc blowfish /source/directory/* [email protected]:/destination/directory
Is there a way to transfer only files modified files just like ...
39
votes
4
answers
48k
views
Official online RPM package browser / search for CentOS [closed]
I am looking for something that resembles packages.debian.org Debian Package Browser only for CentOS 5 and/or RHEL 5 [Red Hat Enterprise Linux].
- 1,952
39
votes
1
answer
73k
views
firewalld vs iptables - when to use which [closed]
TL;DR On new CentOS server installs should I be using firewalld or just disable that and go back to using /etc/sysconfig/iptables ?
firewalld and iptables serve similar purposes. Both do packet ...
- 873