Discuss July 2020

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80 participants
61 discussions

Off Topic bash question
by Jerry Geis 23 Jul '20

23 Jul '20

I have a simple script: #!/bin/bash # index=0 total=0 names=() ip=() while read -r LINE do NODENAME=` echo $LINE | cut -f 1 -d ','` IP=` echo $LINE | cut -f 2 -d ','` names[index]="$NODENAME" ip[index]="$IP" index=`expr index+1` total=`expr total+1` done <<< $(cat list.txt) simple file: more list.txt name1,ip1 name2,ip2 name3,ip3 output when running: sh -x ./test_bash.sh + index=0 + total=0 + names=() + ip=() ++ cat list.txt + read -r LINE ++ echo name1,ip1 name2,ip2 name3,ip3 ++ cut -f 1 -d , + NODENAME=name1 ++ echo name1,ip1 name2,ip2 name3,ip3 ++ cut -f 2 -d , + IP='ip1 name2' + names[index]=name1 + ip[index]='ip1 name2' ++ expr index+1 + index=index+1 ++ expr total+1 + total=total+1 + read -r LINE + echo name1 name1 Question is why is it not reading one line at a time ? All I get is the first one. I'm just trying to build the array of the items in the file and then list them at this point. Thanks Jerry

6 9

USB-serial adapter for CentOS 7
by H 23 Jul '20

23 Jul '20

I need to connect an older APS UPS unit to a machine running CentOS 7. Unfortunately the UPS only has a serial port whereas the computer does not. I am aware that there are USB-serial adapters but that the hardware or the drivers might fall short of expectations. Does anyone have positive experience with such an adapter? Or, conversely, would recommend avoid a particular adapter?

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Brother HL-L2360DW printing quality
by H 23 Jul '20

23 Jul '20

I have the above printer but have not been able to resolve issues with the printing quality in CentOS 7. The test page prints fine but when I print PDF-documents, most recently using Chinese fonts, it is lacking and the pages very hard to read. The settings in the Mate Cups configuration panel are fine and set to 600 dpi, the settings in the printer menu are all OK yet it prints more like maybe 150 or even 75 dpi. Any suggestion what might be wrong?

3 7

C8 - KVM on bridge on VLAN on team issues.
by Lamar Owen 22 Jul '20

22 Jul '20

As part of my initial KVM host on C8 deployment, I decided to set up some HA features on the new host, specifically NIC teaming. Teaming seems to be bond++ of a sort, so I thought I would at least try it. So here's the scenario: 1.) Server with two gigabit ethernet ports, two Cisco switches. 2.) During install, used the 'Server with GUI' group and added the virtualization packages. 3.) During install, set up team0 to include the two gig-e ports set up active-backup (two switches). 4.) During install, set up three bridges, with the slave devices being VLANs pointed to the team0 subinterfaces (using VLANs 68, 101, and 302; 101 is to be the management bridge for the host, with guests on all three VLANs). So, for instance, bridge101 has a slave that is VLAN101 that points to team0.101 with a VLAN ID of 101. The bridge101 interface has a manual IP address, but bridge68 and bridge302 do not (IPv4 disabled; IPv6 Ignore) 5.) After reboot, the bridge101 interface comes up, and I successfully connect to the host, since the install is 8.1.1911, I ran a 'dnf update' up to 8.2.2004, which went well, then I successfully set up and used cockpit, cockpit-bridge, cockpit-machines, again over the IP address on bridge101. Ok, now that the base connectivity is working: 1.) Connect to the host (traffic on bridge101 over team0.101) using virt-manager on my laptop and install a C8 guest, with the network pointed to bridge302, and a manual IP address. 2.) After reboot of guest, there is no IP connectivity to the guest's gateway on VLAN302. 3.) HOWEVER, the gateway's MAC address shows up in the host's bridge fdb for VLAN302, AND in the arp output for the guest; ALSO, the MAC address for the guest shows on the cisco switch 'show mac-address-table' output. The output of 'ip --br link' looks normal for this configuration, but there's a disconnect somewhere. So, since I see that VLAN101 is passing traffic to the bridge correctly (since the management IP is on that VLAN), I try to set up a guest on VLAN101; no dice, no work, but the management IP still works fine. So, does anyone here have a working setup with KVM guests connecting to bridges using 802.1q VLANs on top of a team? Or even on top of a bond (I can reinstall and set it up as a bond easily enough, using active-backup, as far as I know; and, yes, I would reinstall the host from scratch to do this).

4 8

Apache umask
by Emmett Culley 22 Jul '20

22 Jul '20

I need to set the umask for apache to 002. I've tried every idea I've found on the internet, but nothing make a difference. Most suggest that I put "umask 002" in /etc/sysconfig/httpd, but that doesn't seem to make a difference. Other's suggest adding something to the httpd.service script for systemd. And that doesn't make any difference. Any suggestion from this list would be appreciated. Emmett

6 12

Windows guest 4K virt-manager
by Jerry Geis 21 Jul '20

21 Jul '20

I am running CentOS 7 and windows 10 guest. Trying to get 4K on Windows resolution. I did the "virsh edit Win10" and found the video setting an changed it to 64M. After shutting down and booting back up (all of virt-manager) my resolution is still not higher the 2560x Anyone gotten 4K on windows guest ? Whats the trick. I am using QXL. Thanks, jerry

1 0

CentOS 7 rsyslog and ELK
by Pete Biggs 18 Jul '20

18 Jul '20

I asked a similar question about a year ago and didn't get any answers. So I thought I'd try again. What do people do to get their syslog messages on CentOS 7 into a remote ELK stack. I've tried lots of things involving rsyslog, filebeat, redis, logstash and so on in lots of different configurations but nothing really works. I can get rsyslog to talk directly to logstash (acting as a syslog server) but the messages don't have facility or severity codes in them which makes it considerably more difficult to manage the messages. P.

5 6

Re: [CentOS] hardlinks
by Alessandro Baggi 17 Jul '20

17 Jul '20

Il 17/07/20 10:54, Karl Vogel ha scritto: > It depends on the size of the variables in the structure used by the > stat() call. In ext4, the "links" variable is an unsigned 16-bit integer, > so you have your limit of 64k or so. I've worked with systems where > the limit was a signed 16-bit integer, so it maxed out at 32k. > > XFS may be a full 32-bit integer, so your test script could be running > for quite some time. Or it may just allocate space as it needs. It sounds > like you have plenty of room for links, so I wouldn't worry. > > -- > Karl Vogel / vogelke(a)pobox.com / I don't speak for the USAF or my company > > Don't accept your dog's admiration as > conclusive evidence that you are wonderful. --Ann Landers Hi Karl, thank you for your clarification. I will try to rearch this limit (by curiosity)

2 2

[OT] What is the max hardlink number for a single file on XFS
by Alessandro Baggi 17 Jul '20

17 Jul '20

Hi list, I have a little script that uses rysnc and hardlink to perform backups. Some days ago a friend told me that rsync could crash if the hardlink limit is reached. I know (and tested) that for ext4 the max number of hardlink for a single file is 65000 but I can't get a limit on XFS. Due to the fact that I can't get good resources from google search, I tried to reach its limit with a script creating a regular file and create in another dir many hardlinks. Currently I have: -rw-r--r-- 8730476 root root 12 16 lug 12.13 hlink/1 My scripts is trying to reach 20 mln of hardlink so need time to finish but 8730476 of hardlinks is an huge number. Someone know this limit? Thank you in advance.

1 0

Re: [CentOS] Iptables rules not working
by Kaushal Shriyan 17 Jul '20

17 Jul '20

On Fri, Jul 17, 2020 at 2:41 AM Kenneth Porter <shiva(a)sewingwitch.com> wrote: > --On Thursday, July 16, 2020 10:41 PM +0530 Kaushal Shriyan > <kaushalshriyan(a)gmail.com> wrote: > > > I have run the below command but I am still able to connect from the > > internet. Do I need to add any drop traffic policy using nft? > > A single rule doesn't tell us enough. Dump the entire firewall to a > pastebin and post the link here. > > > Hi Kenneth, Please refer to my pastebin link https://paste.centos.org/view/cd55a9a6. Basically I want to allow the below mentioned ruleset on the server (CentOS Linux release 8.2.2004 (Core)) and drop the rest of the network traffic from 0.0.0.0/0 1. Allow http port 80 from 0.0.0.0/0 2. Allow https port 443 from 0.0.0.0/0 3. Allow SSH port 22 only from our office IP:- 219.91.200.59 I look forward to hearing from you. Thanks in advance. Best Regards, Kaushal

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Discuss July 2020