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.

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9 views

CentOS 7 - Isolated cores are not isolated in practice

I have a pair of CentOS 7 servers (7.9.2009) with 8 physical CPUs each. Out of those, I'm trying to isolate cores 4-8 (so 3-7 as the OS sees them). I added the tag isolcpus=3-7 to /etc/default/grub ...
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How can I create a virtual subnet that spans multiple servers?

I have some CentOS 7 servers hosting VMs. The VMs are connected to a network bridge on their respective hosts that allows them to communicate with each other and with the host (via a dummy adapter on ...
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how to hide information of server from scanner system?

i have a site that is behind the cloudflare and with whois domain it's not possible to see the main ip,but with a scanner like https://search.censys.io, everything is showable . information like : ...
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readlink/dirname : missing operand [closed]

I have this problem in my terminal, I've got the following message readlink: missing operand Try 'readlink --help' for more information. dirname: missing operand Try 'dirname --help' for more ...
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How can I make my iptables rules perist after reboot on CENTOS 7

iptables-save > /etc/iptables.ruleset I run this and it doesnt save after reboot please give me a soultion
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On CentOS when I statically assign on ip address to my second interface , my primary nat interface does not work

When I statically assign an IP address to my second interface , my primary NAT interface does not work. I am new to Cent OS and I am using NAT and when I change the second interface statically , my ...
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How to Rename middle part of multiple files [duplicate]

I have some numeric files like: test01-aaa.txt test02-bbb.txt test03-ccc.txt test04-ddd.txt I need to remove aaa,bbb,ccc,ddd part from the name. what is the best way i can do? I tried with 'rename' ...
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Create symlinks with wildcard

I'd like to create a symlink with a wildcard : ln -s jetty_server01.file jetty_*.file So all requests to a file named jetty_*.file will link to target jetty_server01.file, in the same directory. Is ...
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CentOS 7: after reboot, zfs module won't load, no /dev/zfs

After 959 days a reboot was needed on the CentOS 7 system which has used ZFS flawlessly for the past years. I have run yum update once a month during that time. The rebootet system is apparently ...
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CentOS / RHEL Installers Can't see my Computer's Hard Drives

I've tried installing Ubuntu and the installation went flawlessly. However, I'm interested in CentOS / RHEL This is an old Windows Vista era Dell Inspiron 531. I've seen the info regarding AHCI and ...
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Log downloaded packages for mirror

We create local package mirrors with debmirror for deb packages and reposync and createrepo for rpm packages. Is there a way to log the names of the downloaded packages and/or overall size and number ...
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what's the difference: /etc/nfs.conf vs /etc/sysconfig/nfs in RHEL/CentOS 7

in RHEL 7.9, there is /etc/nfs.conf and /etc/sysconfig/nfs. why the two? which one should be edited, and should one and not the other be edited ? It seems /etc/nfs.conf has more in it, but both have ...
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-bash: vdo: command not found in centos stream 9

After installing vdo and kmod-kvdo via dnf, the vdo command doesn't work. Systemctl doesn't recognize vdo.service as well. Vdo version: 8.1.0.316 Vdo release: 1.el9.1 I looked everywhere for a ...
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51 views

How to set static ip in CentOS Stream 9?

I installed a new version CentOS on my hypervisor and I saw that /etc/sysconfig/network-scripts/* doesn't exist. In 8 version I set for example bootproto=static and ipaddr=192.168.88.101. How correct ...
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Polkit rule to allow a user restart systemd service

I created /etc/polkit-1/rules.d/00-manage-docker-daemon.rules file with following rule to allow members of "agroup" to administer (stop/start/restart) docker.service (Centos 7): // Allow ...
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Centos 7 file system corrupted

I'm trying to restore my CentOS 7 virtual Machine as the file system got corrupted. This is the procedure I adopted for the same: Unmount the file system using umount /dev/mapper/centos00-root Tried ...
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22 views

Install -adobe-courier-bold-o-normal--12-120-75-75-m-70-iso8859-1 on CentOS 7, Linux

I am using software called SEISAN. It's earthquake analysis software. When I want to see the plot of waveforms I give the error "unable to get the font". The software is installed on a ...
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iptables accept from specific ips slows down SSH and web

I used ranges of IP address to block other countries, when I use SSH or some of my web services it slows down, if I remove the rules and put everything back to normal it works normally, any ideas?
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LVM Write Stalls When Cache Fills

I'm currently encountering a very perplexing issue with my media server. I have an LV set up with a few disks, and that LV has a write cache attached to it. When the cache isn't full, it works ...
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No longer able to enable my network interface in Centos 8

Environment Operating System: CentOS Linux 8 Virtual Machine running on VMWare Workstation 16 Pro on Windows 11 host. Question I recently had an application lockup while using my VM and I had to power ...
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How to block all incoming connections except one country using firewalld or iptables [duplicate]

I found country IP list: https://www.ip2location.com/free/visitor-blocker I tried to drop all then add the iptables from that list but it didn't work, can I get some help? Thanks.
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37 views

Is there an easy way to RE-install RHEL (or CentOS or Fedora) on existing install?

Is there any easy way to re-install / re-build a "clean" Linux installation on top of existing partitions, etc? In other words, I'm happy with the partitions, the file system, the existing ...
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1answer
61 views

SLOW Wired Speed on Linux, FULL Wire Speed on Windows - 10Gbe

I have 2 Dell Servers. 1 is an R720 and the other an R730. They both have quad port daughter cards supported by Dell. Both cards are RJ45 only and have (2) 10Gbe + (2) 1Gbe ports. 1 Card is an Intel ...
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45 views

dmesg + how to exclude warning messages from dmesg in order to see the completely kernel messages

on our rhel 7.2 server we can see that all lines from dmesg are looks like this uname -r 3.10.0-327.el7.x86_64 [26202771.781769] ACPI Error: SMBus/IPMI/GenericSerialBus write requires Buffer of ...
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Centos 8 kvm bridged guest (OS type hvm) can only communicate with host

A little stumped with my kvm host, especially since I setup the exact same situation on a different host and it works well. I have a proxmox Centos 8 vm that I've had to setup as a kvm host, with a ...
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Can't Install libffi-devel in centos 7

yum install libffi-devel is not working in centos 7 OS. I have a chatbot application(python3) in the centos 7 server which requires many libraries to be installed. At some point i faced the following ...
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Messed up the disk with LVM - cannot boot Centos 7

I had a VM with /boot on sda1 and lvm group on sda2. I've resized the disk and tried to resize the LVM to gain some space for the /var directory. I tried to use the disks utility and create a ...
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23 views

Need for Eclipse IDE [closed]

I am using a system that run on Centos7. My question is the need for separate IDE, in my case an eclipse IDE is preinstalled in PC when the C program can be compiled in CLI using gcc command. Edit: I ...
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39 views

Linux Shell Scripting for reading multiple files and running them

I am using a centos cluster in which I am running LAMMPS software for simulations. Now I have to run multiple files in a folder now each file has a similar type of subfiles i.e they contain 3 files 1. ...
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142 views

Upgraded Postfix and now seeing "discarding EHLO keywords: CHUNKING" in maillog

Upgraded Postfix to 3.5.8-2.el8 on RHEL 8.5 and started seeing below in /var/log/maillog: postfix/smtpd[7575]: discarding EHLO keywords: CHUNKING Reviewed main.cf and master.cf but can't see any ...
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24 views

How to permanent route in Redhat Linux 6.4

I tried route add -net 192.168.3.115 netmask 255.255.255.0 gw 192.168.3.1 but it was not working after reboot , can someone tell me how it works after reboot.
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Centos 7.9 ssh connection failure from macbook

Ssh connection failure from macbook. This stopped working after trying to migrate to Centos 8 MacBook-Pro:~ $ ssh -Y -vvv xxxxxxx@152.3.36.72 -p 32 OpenSSH_8.6p1, LibreSSL 2.8.3 debug1: Reading ...
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33 views

How to move a Linux installation to newer hardware?

I have an existing home server installed with CentOS 7, running on hardware and an SSD that is getting quite old. The system is Intel based: Core i7 4770K @ 3.5 GHz 16 GB Corsair Vengeance DDR3 RAM ...
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31 views

Failed to Switch User?

On machine A and B (both running CentOS 7), I have: # cat /etc/sudoers.d/custom userA ALL=(userB:userB) NOPASSWD:ALL However, on machine A, when I run [userA] $ sudo -ui userB sudo: unknown user: i ...
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Error while compiling GMT(generic mapping tool on centos7) with GDAL

I am having the following error while compiling GMT with GDAL and I am unable to figure out the root cause of it. GDAL has been compiled from the source (following this link). Dependencies too has ...
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50 views

Script for counting and summarising Numbers & Unique numbers in each line

timestamp : IDs returned 20160420084726:- 20160420085418:[111783178, 111557953, 111646835, 111413356, 111412662, 105618372, 111413557] 20160420085418:[111413432, 111633904, 111783198, 111792767, ...
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32 views

Centos 9 missing groups or modules: nodejs

I want to ask question about installing nodejs but probably I had a problem with the repo. I ran command dnf module list nodejs but I got some error messages: Last metadata expiration check: 0:15:21 ...
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32 views

How to downgrade curl on CentOS8?

How to downgrade curl on CentOS8? I want downgrade curl: 7.61.1 => 7.29.0 I tried: yum downgrade curl but no packages marked for downgrade. Last metadata expiration check: 0:15:47 ago on Mon 20 ...
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37 views

SOS: How to recover my os if i delete /boot signuature in Centos?

Today I want to extend my /boot dir in my centos server. before i do this, I have three partion: os was on /dev/nvme1, partition is: /boot mounted on /dev/nvme1p1 /boot/efi mounted on /dev/nvme1p2 /...
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31 views

How to increase size of storage for centos-root without losing data on it and other disks?

Is there any possible way to take space from centos-home and add it to centos-root or /dev/mapper/root? my storage details: Filesystem Size Used Avail Use% Mounted on devtmpfs ...
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53 views

Samba: permission denied

I have a server with a host and a Virtualbox VM.The host is running CentOS 7 and it is updated. Indeed the VM is running CentOS 5 and I know this OS is not supported by several years but I can't ...
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26 views

centos stream 9: cannot connect to hotspot, asking for password in a loop

I have the following dev environment wireless access points (all of them are wired connected to internet) commercial wireless AP FRITZ!Box 7490 1st BRIX mini PC (for hardware info pls. see my ...
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15 views

Prevent gsd-housekeeping and gnome-shell from opening /dev/nvidia0

I want to reset my NVIDIA V100 GPU, but I cannot do that if any process has it open. # lsof /dev/nvidia0 COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME gsd-house 137266 abcdef ...
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94 views

Installing LxQT on CentOS 8

the following command used to work in CentOS 7 for installing LxQT. It seems on CentOS 8 system, this isn't working anymore. It shows some errors. If anybody got any clue about this and likes to ...
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1answer
24 views

Cannot connect lvm2 pv used for virtual-guest os'es to Centos

I have on ubuntu created an encrypted luks partition containing a LVM2 pv which again contain only one volume group "virtual-guests" which I then used with KVM for all the guest os'es. ...
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15 views

how to list authorized AD group and users on CentOS 8

We have one CentOS 8 server where it's integrated with Windows AD so users access it with their Windows credentials. I have a request and need to check out which users and groups are allowed to access ...
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what is the version relationship about postgresql-devel and postgresql

Are the postgresql-devel version have a relationship with postgresql? is it have a version matrix? if I installed postgresql 13, how to install the postgresql 13 mapped postgresql-devel version in the ...
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12 views

prevent VNC-Session from using graphical.target | CentOS Stream 8 RHEL 8

I'm setting up a homeserver and I'm running into the following issue. using tiger-vnc using CentOS Stream 8 using root-user When I start the Server the still connected display shows the localhost ...
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70 views

How to tell rsync to fetch files (fails with "No such file or directory")

sudo rsync -avP ~/wordpress/ /var/www/html/ Error receiving is: sending incremental file list rsync: change_dir "/root/wordpress" failed: No such file or directory (2) sent 20 bytes ...
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13 views

Can't install package perl-Plack on Linux CentOS

When I run the command to install the app, it shows this warning: Error: ea-apache24 conflicts with httpd-2.4.6-97.el7.centos.2.x86_64

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