Linux is a UNIX-like open source operating system with hundreds of distinct distributions, including: Fedora, openSUSE, Ubuntu, Debian, Slackware, Gentoo, CentOS, and Arch Linux. Linux is generally associated with web and database servers, but has become popular in many niche industries and applications.

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I've got a job creating the backend for a mobile app for a company. They will need me to do sysadmin tasks as well.

This app is useless if it can't connect to a server. I need to come up with a redundant setup, ideally over different providers (would like to use Linode and AWS).

I was wondering - what is this called, and how do I set it up? The most similar thing I have done is hosting a database on a separate server - both of those were in the same datacenter. I've read that you do not want the database to accept connections from public IP Addresses.

How do I set this up where there is redundancy over multiple data centers?
Big Business Goals? Which KPIs Will Help You
Big Business Goals? Which KPIs Will Help You

The most successful MSPs rely on metrics – known as key performance indicators (KPIs) – for making informed decisions that help their businesses thrive, rather than just survive. This eBook provides an overview of the most important KPIs used by top MSPs.

Hi I have worked in the capacity of  Microsoft Exchange server and AD for sometime, but recently have received additional duties and one of them is reading email headers. For example making a determination of why an email was blocked, tagged etc.. on firewall appliance. Any guidance on where I can receive resources to learn RFC's and how internet email work. I don't see a lot of material but only unix resources like postfix and sendmail. I I have been kind of winging it and using google but would like some more formal information about this stuff.
If my rsyslog.conf is configured to write *.info *.warn *.kern and some others to /var/log/messages is there any way to identify the local6 *.info messages apart from the *kern and *.warn and others in  /var/log/messages? I've noticed sometimes that the messages contain kern and warn but not just sure what *.info are and if there's an easy way to identify them
I'd rather not have to configure /etc/rsyslog.conf to have another log file for just *.info if it can be avoided. If there's no other way then I might just have to do it but I'm curious what the local 6 information messages actually are.
Ubiquiti Unifi NVR running on Ubuntu 16. I cannot seem to find how to configure email alerts?  Can it now be done unless you have the physical NVR?
how to grep multiple awks

$ awk '{print;}' employee.txt
100  Thomas  Manager    Sales       $5,000
200  Jason   Developer  Technology  $5,500
300  Sanjay  Sysadmin   Technology  $7,000
400  Nisha   Manager    Marketing   $9,500
500  Randy   DBA        Technology  $6,000

$ awk '{print $2,$5;}' employee.txt
Thomas $5,000
Jason $5,500
Sanjay $7,000
Nisha $9,500
Randy $6,000

in above query how to tweak to see  see all records whose name starts with 'S' and Salary greater than '6000'

in above query how to tweak to see  see all records whose name starts with 'S' and Salary greater than '6000' and Department Starts with  'T'

100  Thomas  Manager    Sales       $5,000     08/08/1988 6:00:01AM
200  Jason   Developer  Technology  $5,500 08/08/1989 7:00:02AM
300  Sanjay  Sysadmin   Technology  $7,000 08/08/1982 9:00:03AM
400  Nisha   Manager    Marketing   $9,500 08/08/1981 10:00:04AM
500  Randy   DBA        Technology  $6,000 08/08/1981 11:00:5AM
if it has joined date and time as above
in above query how to tweak to see  see all records whose name starts with 'S' and Salary greater than '6000' and Department Starts with  'T' and joined between particular date time to particular date time say  08/08/1982 9:00:03 AM till 08/08/1981 10:00:04AM
i need to use above in a zgrep command
Dear Experts

We are having web-based application on linux which uses LAMP  which is production server recently the web-based application stops working for some time later it resumes back and when checked the /var/log/messages can find the following
kernel: Out of memory: Kill process 249606 (httpd) score 32 or sacrifice child
Sep 13 13:19:27 NYSWB kernel: Killed process 249606, UID 48, (httpd) total-vm:2826972kB, anon-rss:1334424kB, file-rss:2044kB
attached /cat/proc/meminfo and also fdisk -l , the system has 32G of physical RAM,
please suggest should i have to create one more swap partition OR should I have to edit swap config if yes please help me with steps, or any other steps on any config to be done please let me know, thank you.
Dear Experts

I am running crm system web-based which is LAMP stack the web root is /var/ww/html/crmapp and the CRM system reads the files from windows share that is from 2 windows server and executes the logic as per the process developed but I am getting following error from /var/log/messages , attached /etc/fstab, df -h and nswitch.conf, can you please help me in first windows share mount to the same path of web root is it recommend and also is the fstab entires are correct please suggest as the system is very slow.

automount[2560]: syntax error in map near [ * -fstype=autofs,-Dhost=& file: ]
Sep 11 20:06:15 NYSWB automount[2560]: syntax error in map near [ * -fstype=autofs,-Dhost=& file: ]
Sep 11 20:06:17 NYSWB automount[2560]: syntax error in map near [ * -fstype=autofs,-Dhost=& file: ]
Sep 11 20:06:19 NYSWB automount[2560]: syntax error in map near [ * -fstype=autofs,-Dhost=& file: ]
Sep 11 20:06:21 NYSWB automount[2560]: syntax error in map near [ * -fstype=autofs,-Dhost=& file: ]
Sep 11 20:06:23 NYSWB automount[2560]: problem reading master map, maximum wait exceeded
Sep 11 20:06:23 NYSWB automount[2560]: automount: warning: could not read at least one map source after waiting, continuing ...
Sep 11 20:06:23 NYSWB automount[2560]: syntax error in map near [ * -fstype=autofs,-Dhost=& file: ]
Hi there,

I copied the OS drive from the Azure environment as I want to work on a copy of the VM locally instead of in the cloud.  When I turn on the VM, it fails because it is trying to attach a data disk that I didn't download.  The data disk is 1TB so I don't want to download it just to attach it and not use it.  How can I fix this copied VM so that it only tries to boot and not look for this second drive?  I believe I can remove it by putting int he root password so that I can do some maintenance, but with Azure VMs, the root password isn't set and I don't want to change it just in case something happens on the live VM.   Is there another way around it?

I'm getting these errors:

fsck.ext4: Unable to resolve 'UUID=451a8a0d-0c99-4b34-8702-361627fda1a2a' [FAILED]
*** An error occurred during the file system check.  
Give root password for maintenance (or type Control-D to continue):

Dear Experts
We are having CRM application which is web-based runs on LAMP stack. the operation team reports between specific time period user get time out when they save the records or convert the records or retrieve the records, can you please suggest on how to capture log files which occurs during that time for example 5pm to 6pm, only during this time I would like to capture a following log files.
1) /var/log/mysql.log
3) /var/log/slowquerylog
please help with steps on above 1 to 4 log capture during specific time period , this will be helpful to investigate , thank you very much.
Hi Experts,

     I had build and run a docker image like this.

docker build -t harvest-trove:1.0.3 .
docker run --name trove_pull ${trove_environment[@]} -d -restart always harvest-trove:1.0.3 start pull                 

Open in new window

I want to use docker compose for the above two commands

I had created the docker compose like this.

      build: .
      image: harvest-trove:1.0.3
                -  .:/home/trove
        -  web-variables.env
            command: python3 migrate
    image: harvest-trove
       - web-variables.env
         - harvest-trove
       command: harvest-trove:1.0.3 start pull

Open in new window

when I run docker-compose up I get the following error.

error with docker-compose up
Please help me in fixing this issue.

With Many thanks,
Bharath AK
Fundamentals of JavaScript
LVL 12
Fundamentals of JavaScript

Learn the fundamentals of the popular programming language JavaScript so that you can explore the realm of web development.

How to connect already running mariadb container

I found this query

$ docker run --name appName --link some-mariadb:mysql -d application-that-uses-mysql

i am confuse with the syntax ?
can any one tell me how to use this ??
I created a 301 redirect on .htaccess file on linux shared server website

I did it incorrectly and have changed redirect to another website

But firefox browser windows 10 (my machine only: I did not try on other computers) still has first redirect.
I dont want to close browser or restart my windows 10 computer
How can I Read more than 10280 bites data using PHP
$read = socket_read($sock,10240);
it can showing max 3000 bites.
Hi Experts,

Over the last few years I've been working for a couple of fairly big companies that allow developers, devops and other teams with in the company to request new virtual machines to meet their needs.

From what I have seen in both cases these companies use custom built in-house solutions, that aren't very good. I'm looking for a solution that has a easy to use web base form for the end user to request the server but has an approval chain and back ends into esxi to automate the requests.

This should work with Windows and Linux deployments.

Does anyone know if there is such a tool already on the market? Also what tools are all you other sysadmins using to help automate this kind of requests?
awk query
 unzip -c  xyz.log.20180905.gz| awk '$0>= "2013-Sep-09 18:33" && $0 <="2013-Sep-09 23:15"'| grep '|[1-9][0-9][0-9][0-9][0-9]|0000'|wc -l
Zip file too big (greater than 4294959102 bytes)
  End-of-central-directory signature not found.  Either this file is not
  a zipfile, or it constitutes one disk of a multi-part archive.  In the
  latter case the central directory and zipfile comment will be found on
  the last disk(s) of this archive.
how to learn awk any good video tutorials on it?
please advise
Facing Issue  With Oracle Linux.
this system is not registered with ULN. ULN support will be disabled.

ULN Erroe
I recently got an older server. 6gb RAM, 1x2tb RAID array. 4 core CPU. Literally an old file server.

I upgraded their server and took this one.

It originally came with Server 2008, but I was unable to recover the key (they wiped the drives and it didn't have a sticker on it.

I was wondering of a linux OS with a web-based GUI. I have used Webmin in the past, and I like it, but it doesn't seem to be updated very often.

I want to know if there are any similar to you Webmin that you like to use. I don't really want to hang out in my office staring at a screen and I ain't great with terminal commands (through SSH). I like the module options like in Webmin. I have also tried Cockpit project, but it doesn't have much on it. And ClearOS is not that easy to use when setting up samba share. Amahi, I have the same issues.

What are your recommendations??
i try to add a disk to ubuntu.
i used this help

now i add a new one. it should be on /dev/sde.
i can't see it on pvdisplay and when try tp fdisk /dev/de1
it says you can create a dos partition.
Device does not contain a recognized partition table. Created a new DOS disklabel with disk identifier 0xbc6fc5e9.

Dear Experts

in linux server of centos,  we are running crm which is web based application apache, mysql and php once in few hours users are getting timeout and this is affecting very badly,
1. would like to fetch the log reports of server resources consumption like  RAM, CPU to understand the issue is occurring due to over load of that particular time.
2.  would like to fetch apache logs and mysql logs of that particular time
to determine the time that users are facing issues of application time out , Can I ask software developer to provide me time out occurred and application closed  date and time and during that time check the server resource utilisation which will help me to trace the issue is it due to server or application level.
please help on best practice on such cases.
Microsoft Azure 2017
LVL 12
Microsoft Azure 2017

Azure has a changed a lot since it was originally introduce by adding new services and features. Do you know everything you need to about Azure? This course will teach you about the Azure App Service, monitoring and application insights, DevOps, and Team Services.

Hi Experts,
How to install apparmor in alpine Linux docker image.
Please share me the steps to do it.
is there any free open source gui for modsec managment and monitoring?
zgrep 'XYZ|AB|MASTER' AAAA.log.20180904.gz | grep '|[1-9][0-9][0-9][0-9][0-9]|0000' | wc -l

can you please advise what is the meaning of above zgrep command

where i can find, practice and learn above kind of commands

how grep and egrep are different
how to learn regular expressions used in queries

Please advise
We have a linux virtual machine which all of sudden stops responding.
ESXI host is vsphere 6.
In the linux \var\log\messages we see following errors:
kernel: pvscsi: device reset on scsi3:5
But the VM does not have any disk with scsi ID of "3:5" as it only has 2 scsi controllers.

Oracle support has pointed out the following errors in the oracle logs:-
[OCSSD(7710)]CRS-1614: No I/O has completed after 75% of the maximum interval. Voting file ORCL:CRSVOL2 will be considered not functional in 49600 milliseconds

And the following iostat data collected by oracle showing "iowait" of 62% at the time of issue
avg-cpu:  %user   %nice %system %iowait  %steal   %idle
                    0.96    0.00      1.09          62.72    0.00      35.23

Also, iostat shows that the number of reads/sec and writes/sec go to zero at that time.

Vsphere shows low disk latency of 2ms generally but with a peak of 18 ms.
And the CPU ready is also low - 2-3%.

Vmware.log file for the VM shows occasional cmd aborted error but not continously.
Vmkernel log on the esxi host shows following error occasionally:-
PVSCSI: scsi1:5: aborting cmd 0x2b
And for the last server hang we saw the following logged 7 minutes before the hang in the vmware.log of the VM :-
2018-09-03T11:03:28.277Z| vmx| I125: SSL: EOF in violation of protocol
2018-09-03T11:03:28.277Z| vmx| I125: SOCKET 1137 (265) recv error 0: Success
2018-09-03T11:03:28.277Z| vmx| I125: Vix: [16008476
Hello Experts,
Need help for building RPM bundle with rpms or source RPM for Linux RHEL or CentOS. I am planning to build one single RPM which will deploy/extract multiple rpm so as to automate the all dependency packages need for the environment will get in one single RPM. In this need to generate one gpg key and will deploy this on one web server so if I want this rpm bundle i will only pull/wget to repo file and will give one gpg key. After enabling this I can install all rpm on server.

i.e. one rpm consider as web.rpm contain 1. java-1.8.0-openjdk- 2. httpd-2.4.6-80.el7.centos.x86_64.rpm 3. subversion-1.9.7-1.x86_64.rpm 4. php7.1rpm

Need SPEC file for this and where to keep source RPM whether in SRPMS or SOURCES or RPMS.
data no align after i do cat in unix this is my script
cat data*.txt|grep -v ^UNIT_CDE|awk '{print $1,",",$2,",",$3,","$4,",",$5,",",$6,",",$7,",",$8,",",$9,","$10,",",$11,",",$12,",",$13,",",$14,",",$15,","$16,",",$17,",",$18,",",$19,",",$20}' >>  mergetstneg.txt






Linux is a UNIX-like open source operating system with hundreds of distinct distributions, including: Fedora, openSUSE, Ubuntu, Debian, Slackware, Gentoo, CentOS, and Arch Linux. Linux is generally associated with web and database servers, but has become popular in many niche industries and applications.