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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Error: Package: R-core-devel-3.4.0-2.el6.x86_64
           Requires: libicu-devel
yum can be configured to try to resolve such errors by temporarily enabling
disabled repos and searching for missing dependencies.
To enable this functionality please set 'notify_only=0' in /etc/yum/pluginconf.d/search-disabled-repos.conf

--> Running transaction check
---> Package R-core-devel.x86_64 0:3.4.0-2.el6 will be an update
--> Processing Dependency: libicu-devel for package: R-core-devel-3.4.0-2.el6.x86_64
---> Package kernel.x86_64 0:2.6.32-642.11.1.el6 will be erased
--> Finished Dependency Resolution
Error: Package: R-core-devel-3.4.0-2.el6.x86_64
           Requires: libicu-devel
 You could try using --skip-broken to work around the problem
** Found 2 pre-existing rpmdb problem(s), 'yum check' output follows:
tomcat6-admin-webapps-6.0.24-98.el6_8.noarch has missing requires of tomcat6 = ('0', '6.0.24', '98.el6_8')
tomcat6-webapps-6.0.24-98.el6_8.noarch has missing requires of tomcat6 = ('0', '6.0.24', '98.el6_8')
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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

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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

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I have linux application account and  would like to restrict the user to login directly. I want this account to be under sudoers. users can login and sudo into this account. How do i do that in linux?

What is the difference between puppet class vs module?
I am running redhat linux 6.8

i want to build a new RPM using the source code of nodejs (6.10)

As i am new to RPB build, i am looking for assistance with creating RPM.
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 ?

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
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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.
We had someone (a junior admin) go in and delete a bunch of rpms using rpm -e a few weeks ago.  Now when I try to reinstall the packages that are missing I get this following:

Total download size: 894 k
Installed size: 2.4 M
Downloading Packages:
mysql-5.1.73-7.el6.x86_64.rpm                                                                                               | 894 kB     00:00
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
mysql-5.1.73-7.el6.x86_64 was supposed to be installed but is not!
  Verifying  : mysql-5.1.73-7.el6.x86_64                                                                                                       1/1
  Verifying  : mysql-5.1.73-7.el6.x86_64                                                                                                       2/1

  mysql.x86_64 0:5.1.73-7.el6


I already trying yum clean all and rebuilding the rpm database.  Any other suggestions?  The error message is kind of cryptic.
On Centos 6.5 I have several cron jobs that been running without any problem.
I just added a now job

22 4 * * * python3.5 /home/chariya/python/ spc > /home/chariya/python/log

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Which ran as scheduled but no result and no log produced (in ~/python/log)
Here is the job logged in /var/log/cron

Jul 17 05:18:01 web511 CROND[31384]: (chariya) CMD (python3.5 /home/chariya/python/ hyb > /hom                      e/chariya/python/log)

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We have a backup of a machine that had been virtualized on Xen. The image was an LV snapshot, exported to raw disk .IMG with DD, then converted to VMDK with QEMU-IMG and imported to Vmware ESXi 6.

The machine boots to the first menu where three versions are offered but no matter which option is selected there is an immediate black screen.

An internet search brought up suggestions related altering the GUI boot (didn't help and we don't get that far) or for reinstalling/repairing GRUB. Following those suggestions we've booted from a CENTOS 6 ISO and selected the option to recover the existing OS.

The existing install is detected on /dev/sda and the recover process mounts /dev/sda1 on /mnt/sysimage/boot ; /dev/sda2 on /mnt/sysimage and indicates that the detected OS was mounted on /mnt/sysimage

The recovery steps then indicate we should chroot /mnt/sysimage and then reinstall GRUB. The chroot command fails with "Failed to run command /bin/sh Input/Output error" and we cannot continue

Stuck and don't know what to try next....
Hello expert,
I would like setup netmap on ubuntu release 15. Thanks.
I perused the answers in this excellent Unix Stack Exchange article;

and tested it earlier yesterday on an Ubuntu Linux 16.04 instance ,
Lenovo Thinkstation quad core desktop , and saw that the autofs rule hides
my /home/frank directory and /media/data1 directory.

    Why does autofs restart hide my /home/frank subdirectory so I cannot
reboot and login again?

   I read in Evi Nemeth's Unix and Linux System Administration Handbook , 4th Edition,
Page 715, that "when you list the contents of an automounted filesystem's parent directory ,
the directory appears empty and you cannot browse the automounts in a GUI filesystem
browser such as Nautilus and that the photos filesystem is automounted under /portal .
It's accessible through its' full pathname". But, that is not what I observe.
Instead when I cd to /portal/photos the kernel says "no such filename or directory".
Furthermore , I cannot login to my home directory.  

    How do I fix the autofs procedure, which is an alternative to modifying

    Why is the autofs hint preferred by Ubuntu Linux practioners
over  modifying /etc/fstab for the purpose of creating a permanent
mount point for a CD, DVD or USB drive.

    Any help is greatly appreciated.
Linux newbie here.
I am trying to change the hostname of a RedHat 7  linux machine.
I tried to change the hostname by entering changed the etc/sysconfig/network file changed an entry on etc/hosts
entered hostnamectl set-hostname "myhostname" --static
tried to follow the nmtui command do it the gui way.

but all the above changes do is change the hostname till next reboot.
how can I change the hostname permanently and make it persist after a reboot

Hi Friends,

We have CentOS 6.4 server and it was working fine, now its saying centos 6 booting up in 10 seconds and freeze and just showing single cursure and unable to do anything  and unable to boot again if hard reboot last time we had error “kernel:ECC/ChipKill ECC error”  Kindly suggest for further please help me

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I have to remove older files which are older than one month back from linux server.

How can I
Hi All:

I want to implement TR181 by using klish in linux, where can I get the tutorials and starting point?


Using FileZilla or another FTP program and entering the IP address, Username, password on port 22 but is not accessing Fedora. Error message says Fedora server is refusing the file transfers. Am new at Fedora so am not sure what to do here. Need to upload files in the var/www/html but Fedora won't allow it. Any help would be appreciated.
I assigned 15Gb of my hard disk to Linux Mint but I later found it's quite not enough. How can i adjust the size
If i put in a data cd it appears on the desktop. i tried different dvd,it did not work. In fstab it shows as:

dev/scd0 /media/cdrom0 udf,iso9660 user,atime,auto,rw/dev/exec/,suid 0 0.

the RW burner is the same except scd1 and cdrom1.

i do not see any of that in mtab.
root@ansible01:/etc/ansible# ansible-playbook create_vms.yml -e

PLAY: ***************************************************************************

TASK [fail msg=One of the mandatory variables not defined] **********************
fatal: []: FAILED! => {"failed": true, "stdout": ""}

NO MORE HOSTS LEFT **************************************************************

PLAY RECAP **********************************************************************    : ok=0    changed=0    unreachable=0    failed=1

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