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Linux OS Dev

Kernel programming for Linux operating systems can be done with many different languages; C, C++, Python, Perl and Java, which are some of the most common languages used.There are also many different varieties of Linux, such as Ubuntu, Fedora and OpenSUSE.

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i installed bind and setup example.com domain on my centos 6.9.

trying to find what is the causes here.

[root@dns01 ~]# named-checkconf /etc/named.conf
[root@dns01 ~]#

[root@dns01 ~]# named-checkzone example.com /var/named/rev.example.com
zone example.com/IN: loaded serial 2017091501

[root@dns01 ~]# named-checkzone example.com /var/named/fwd.example.com
zone example.com/IN: loaded serial 2017091501

[root@dns01 ~]# host -v -t ns example.com.
Trying "example.com"
;; connection timed out; trying next origin
Trying "example.com"
;; connection timed out; no servers could be reached
Free Backup Tool for VMware and Hyper-V
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Restore full virtual machine or individual guest files from 19 common file systems directly from the backup file. Schedule VM backups with PowerShell scripts. Set desired time, lean back and let the script to notify you via email upon completion.  

Hi Team,

We have folder called /opt/app
inside /opt/app we are running applications as elasticsearch and kibana in below respective folders.


and processes are running in those folders as we.

Due to space issue. Now i want to mount to /opt/app folder without any data loss on the fly?
is it possible or not? if possible could you please suggest me what is the best way to proceed?
Can i able to add RHEL6 and RHEL7 repos to spacewalk?

I have account on redhat where i can download all the rhel6/7 packages.  not sure how to add to spacewalk so i can utilize spacewalk to do lot of operations.
I am installing spacewalk on RHEL7.

I was following this article.


I am getting the following error when i execute,
yum -y install spacewalk-postgresql

Error: Package: jboss-jstl-1.2-api-1.0.3-15.1.el7.noarch (epel)
           Requires: mvn(org.jboss.spec.javax.servlet:jboss-servlet-api_3.0_spec)
Error: Package: jboss-jstl-1.2-api-1.0.3-15.1.el7.noarch (epel)
           Requires: mvn(org.jboss.spec.javax.el:jboss-el-api_2.2_spec)
Error: Package: jpam-0.4-28.el7.x86_64 (spacewalk)
           Requires: apache-commons-beanutils
Error: Package: jboss-jsp-2.2-api-1.0.1-15.1.el7.noarch (epel)
           Requires: mvn(org.jboss.spec.javax.servlet:jboss-servlet-api_3.0_spec)
Error: Package: spacewalk-jpp-workaround-2.3.5-1.el7.noarch (spacewalk)
           Requires: apache-commons-validator
Error: Package: struts-1.3.10-14.1.el7.noarch (epel)
           Requires: mvn(commons-validator:commons-validator)
Error: Package: apache-commons-chain-1.2-12.1.el7.noarch (epel)
           Requires: mvn(commons-digester:commons-digester)
Error: Package: python-cheetah-2.4.4-4.el7.x86_64 (epel)
           Requires: python-pygments
Error: Package: spacewalk-jpp-workaround-2.3.5-1.el7.noarch (spacewalk)
           Requires: apache-commons-digester
Error: Package: jboss-jsp-2.2-api-1.0.1-15.1.el7.noarch (epel)
           Requires: mvn(org.jboss.spec.javax.el:jboss-el-api_2.2_spec)
Error: Package: …
--> Finished Dependency Resolution
Error: Package: spacewalk-taskomatic-2.7.115-1.el7.noarch (spacewalk)
           Requires: hibernate3 >= 3.6.10
           Available: hibernate3-3.2.4-1.SP1_CP01.9.jpp5.noarch (jpackage-generic)
               hibernate3 = 3.2.4-1.SP1_CP01.9.jpp5
Error: Package: spacewalk-java-2.7.115-1.el7.noarch (spacewalk)
           Requires: tomcat-taglibs-standard
Error: Package: spacewalk-java-2.7.115-1.el7.noarch (spacewalk)
           Requires: hibernate3-ehcache >= 3.6.10
Error: Package: spacewalk-java-2.7.115-1.el7.noarch (spacewalk)
           Requires: hibernate3-c3p0 >= 3.6.10
Error: Package: cglib-2.1.3-4.jpp5.noarch (jpackage-generic)
           Requires: asm >= 1.5.3
           Available: asm-1.5.3-7.jpp5.noarch (jpackage-generic)
               asm = 1.5.3-7.jpp5
Error: Package: spacewalk-taskomatic-2.7.115-1.el7.noarch (spacewalk)
           Requires: hibernate3-c3p0 >= 3.6.10
Error: Package: spacewalk-taskomatic-2.7.115-1.el7.noarch (spacewalk)
           Requires: concurrent >= 1.3.4-21
           Available: concurrent-1.3.4-9.jpp5.noarch (jpackage-generic)
               concurrent = 1.3.4-9.jpp5
Error: Package: spacewalk-java-2.7.115-1.el7.noarch (spacewalk)
           Requires: apache-commons-el
Error: Package: spacewalk-taskomatic-2.7.115-1.el7.noarch (spacewalk)
           Requires: hibernate3-ehcache >= 3.6.10
Error: Package: spacewalk-java-2.7.115-1.el7.noarch (spacewalk)
           Requires: hibernate3 …
Dear Experts

We are running rhel7 that is redhat enterprise linux 7.3 and our application sugarcrm requires php-imap but rhel7 does not support php-imap hence downloaded epel and tired to install I get below dependency issue
downloaded and install php56-php-imap from rpm finder below error,
rpm -Uvh php56-php-imap-5.6.31-1.el7.remi.x86_64.rpm
error: Failed dependencies:
        php56-php-common(x86-64) = 5.6.31-1.el7.remi is needed by php56-php-imap-5.6.31-1.el7.remi.x86_64
[root@crm1 indar]#
should I have to disable rhel repo and depend on epel and install if yes can you please provide the steps for epel for rhel7
thanks in advance
how to transfer
site booksmarks to shared bookmarks in winscp

please advise

how to teach winscp remember password. Every time entering password is pain for me. please advise
good morning

I am currently presenting problems with three virtual servers, with Redhat operating system version 6.6, since it is not loading the operating system correctly and does not finish starting.

Restart the server repeatedly, migrate another host, and the fault persists. Attach pictures of the errors I am observing.

Stay tuned to your comments.

Best regards.
Dear Experts

We have come across critical issue that is sugarcrm loading automatically also frequently getting logout, for this support have suggested the below, can you please suggest on how to disable this.

caching enabled (opcache / memcahce) can you disable this to determine if it is playing a role

our instance php modules for your information
s http://crm1.shriramproperties.com/info.php

thanks in advance
[Webinar] Lessons on Recovering from Petya
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Skyport is working hard to help customers recover from recent attacks, like the Petya worm. This work has brought to light some important lessons. New malware attacks like this can take down your entire environment. Learn from others mistakes on how to prevent Petya like worms.

Hello ,

I have a problem with interfaces on a multihomed topology. My interfaces can not ping each other and can not ping theirselves too
sysctl as given below.

But it is able to ping the interface ip when i directly write ping , if the both interface are not able to ping this interface's ip how does it ping it or from where ?

I have to let them have access each other how shoud i do it ?

Note: loopback interface activated
Note2: em interfaces are all down

[root@spd network-scripts]# sysctl -p
net.ipv4.ip_forward = 1
net.ipv4.conf.p1p1.rp_filter = 2
net.ipv4.conf.p1p2.rp_filter = 2
net.ipv4.conf.all.rp_filter = 2
net.ipv4.conf.default.rp_filter = 2
net.ipv4.conf.lo.rp_filter = 2
net.ipv4.conf.p1p1.accept_local = 1
net.ipv4.conf.p1p2.accept_local = 1
net.ipv4.conf.all.accept_local = 1
net.ipv4.conf.default.accept_local = 1
net.ipv4.conf.lo.accept_local = 1
net.ipv4.conf.default.arp_filter = 0
net.ipv4.conf.all.arp_filter = 0
net.ipv4.conf.p1p2.arp_filter = 0
net.ipv4.conf.p1p1.arp_filter = 0
net.ipv4.conf.lo.arp_announce = 2
net.ipv4.conf.all.arp_announce = 2
net.ipv4.conf.default.arp_announce = 2
net.ipv4.conf.p1p1.arp_announce = 2
net.ipv4.conf.p1p2.arp_announce = 2

Open in new window

PING ( from p1p1: 56(84) bytes of data.

--- ping statistics ---
3 packets transmitted, 0 received, 100% packet loss, time 2055ms

[root@spd network-scripts]# ping -I p1p1
PING ( from p1p1: 56(84) bytes of data.

--- ping statistics ---
4 packets transmitted, 0 received, 100% packet loss, time 3064ms

[root@spd network-scripts]# ping -I p1p2
PING ( from p1p2: 56(84) bytes of data.

--- ping statistics ---
2 packets transmitted, 0 received, 100% packet loss, time 1038ms

[root@spd network-scripts]# ping -I p1p2
PING ( from p1p2: 56(84) bytes of data.

--- ping statistics ---
3 packets transmitted, 0 received, 100% packet loss, time 2060ms

Open in new window

[root@spd network-scripts]# ping
PING ( 56(84) bytes of data.
64 bytes from icmp_seq=1 ttl=64 time=0.019 ms
64 bytes from icmp_seq=2 ttl=64 time=0.022 ms
64 bytes from icmp_seq=3 ttl=64 time=0.017 ms
64 bytes from icmp_seq=4 ttl=64 time=0.015 ms

Open in new window

Open in new window

[root@localhost httpd-2.4.27]# ./configure
checking for chosen layout... Apache
checking for working mkdir -p... yes
checking for grep that handles long lines and -e... /bin/grep
checking for egrep... /bin/grep -E
checking build system type... x86_64-pc-linux-gnu
checking host system type... x86_64-pc-linux-gnu
checking target system type... x86_64-pc-linux-gnu
configure: Configuring Apache Portable Runtime library...
checking for APR... no
configure: error: APR not found.  Please read the documentation.
when patching suse linux i noticed one package did not get updated for few nodes. other node it got updated.

-  All three servers are SUSE 10 SP4.
- all connected to same repo

trying to tshoot this issue. can some one give me some insight on how to tackle this issue.

I come from redhat background so i am just walking with suse linux.

winscp how to sudo as admin?
I currently logged in as my user say xyz but i am not able to delete particulr folder/directory. I have to login or pseudo as admin user say rrr to that. how to psedo in the winscp to rrr user?pleaseadcise

winscp how to compare 2 different unix users say xyz and abc by opening xyz on left hands side and abc on right hand side. As of now on the left hands side i was able to open my windows laptop folder structure like C drive etc and on right hands side i am able to open one unix user like abc or xyz etc. please advise
I have a Linux bind server hosting a

the rzone  file in /var/named/data/51-168-192.zone

the SOA line says this is    "IN SOA  netsvc.int.alconi.com.   root.netsvc.int.alconi.com. 203 3h 1h 1w 5m

I want to create a windows DNS in the another namespace that would be       "win2016.int.alconi.com" or maybe "win.alconi.com"  with its own DNS servers, can I do this ?

should I create another subnet for the win.alconi.com?

if so how ,

I am very ignorant on this , and really really could use some help
Hi Experts

I am trying install CentOS 6.8 minimal thru kick start on an Virtual Machine(VMware workstation) and assigning kickstart file thru http on another VM, kickstarts goes thru smoothly creates partitions and all but stuck on repo section unable to find repo following types of error, errors attached

Stuck with this error from few days, Please help

In /var/www/html location has ks.cfg file and all centos 6.8 minimal dvd content as it is

[root@srv1 html]# ls
CentOS_BuildTag  isolinux                  RPM-GPG-KEY-CentOS-6
EFI              ks.cfg                    RPM-GPG-KEY-CentOS-Debug-6
EULA             Packages                  RPM-GPG-KEY-CentOS-Security-6
GPL              RELEASE-NOTES-en-US.html  RPM-GPG-KEY-CentOS-Testing-6
images           repodata                  TRANS.TBL

Open in new window

Section of kickstart file i am assign is shown below
# Kickstart file automatically generated by anaconda.

url --url=
lang en_US.UTF-8
keyboard us
network --onboot yes --device eth0 --mtu=1496 --bootproto static --ip --netmask --gateway --noipv6 --nameserver --hostname nac17
network --onboot no --device eth1 --bootproto dhcp --noipv6 --hostname nac17
rootpw  --iscrypted 
# Reboot after installation
reboot --eject
firewall --disabled
authconfig --enableshadow --passalgo=sha512
selinux --enforcing
timezone --utc Asia/Kolkata

Open in new window


What is the difference between puppet class vs module?
Hi Experts

I have a customer that has Linux Centos 6.5 samba file server installed. (old server)
They also have another server that has Centos 7 samba file server installed. (new server)
My scope on the project is to migrate from old server to new server.
I'm not very good in Linux but I understand that it requires to create Linux users as well as samba user for file sharing permission.

What is the proper way to migrate shared folder to new server including [file and folder permissions] and [list of users(linux and samba)"]?
Example we can use Robocopy in Windows server to migrate permission, how about in Linux ? Could you please provide step by step ?

Automating Terraform w Jenkins & AWS CodeCommit
Automating Terraform w Jenkins & AWS CodeCommit

How to configure Jenkins and CodeCommit to allow users to easily create and destroy infrastructure using Terraform code.

Dear All,

We have created a chrooted jail environment for our SFTP access. Using chrooted environment, we restrict users either to their home directory or to a specific directory. Now my question is if there's anyway we can an additional username to access the same home directory for other username? Or any other words, is there anyway I can assign different usernames to the same home-directory and have it chrooted jail?

Below is our current config if that helps:

group add sftponly

vi /etc/ssh/sshd_config

#Subsystem sftp /usr/libexec/openssh/sftp-server
Subsystem sftp internal-sftp
Match Group sftponly
ChrootDirectory %h
ForceCommand internal-sftp
X11Forwarding no
AllowTcpForwarding no

systemctl restart sshd.service

useradd USERNAME –g sftponly –s /bin/false
passwd  USERNAME

chown root /home/USERNAME
chmod 755 /home/USERNAME
chmod 755 /home/USERNAME/SFTPWRITE

setsebool –P ssh_chroot_rw_homedirs on
How to turn on computer automatically from crontab in Cantos & Ubuntu ?
Have a telecommunication server that switched over to its backup. After the switchover we noticed a couple of files that can't be deleted.

[root@LABSYS2 log]# ls -ltr
ls: cannot access 1000025.DBG: Input/output error
ls: cannot access 10002CB.AUD: Input/output error
total 769808
-????????? ? ?          ?            ?            ? 10002CB.AUD
-????????? ? ?          ?            ?            ? 1000025.DBG

I tried to find the inode of the file and use it to delete but "ls -il" did not return inodes  (it only did for other files in dir)

ls -li
find ./ -inum <inode number> -exec rm -i {} \;

Please offer any suggestions.

Which logformat should use to entry like this:

[2016-12-30T23:43:14.0013+00:00] [OHS] [ERROR:32] [] [core.c] [client_id:] [host_id: oracle9] [host_addr:] [tid: 140543029438784] [user: ia] [ecid: 005HEZ3wEdAF4Ej6D3NES0008f000RFT] [rid: 0] [VirtualHost: FCDB.pays:443]  File does not exist: /pmo/admin/pmo_oracle29/OHS/htdocs/index.html
I have nas disk mounted as nfs mount point i linux. how to create a dd image of this. the mount point is like that
tor01-nas.llg:/export/shared/ps_oem   nfs     2G  9.9K  2G    1% /oem1
I have two servers that recently shut down due to a UPS failure.  Effectively 2 identical builds - Centos 6.6 OS Servers on Dell hardware RAID 5 over 4 drives.  There are some encrypted volumes that do not show up after this unscheduled/ungraceful shut down happened.  The server is rebooted but there is no dev/mapper/crypot device showing.    I think that the 'cryptsetup luksOpen /dev/sda2 crypt command is failing at boot.
Error message when trying to access volumes says:  "fsk.ext4: No such file or directory while trying to open /dev/vg_00/DIRECTORYNAME.  The superblock could not be read or does not describe a correct ext2 file system.  If the file is valid and it really contains a ext2 file system (and not swap or ufs or something else) then the superblock is corrupt and you might try running ef2sck with an alternate superblock. eft2ck -b 8193.
This is on both servers after an ungraceful shutdown.

Linux OS Dev

Kernel programming for Linux operating systems can be done with many different languages; C, C++, Python, Perl and Java, which are some of the most common languages used.There are also many different varieties of Linux, such as Ubuntu, Fedora and OpenSUSE.

Top Experts In
Linux OS Dev