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')
Congratulations! You’re Certified – Now What?
Congratulations! You’re Certified – Now What?

Starting a new career can be overwhelming. Becoming certified in your field of expertise is a great start, but where do you go from here?  Here are some tips to help you on your career journey.

Hi, please need guidance on how to fix the npm error. Thanks so much in advance.

# rpm --query centos-release

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# node --version

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# npm --version

    throw err;
Error: Cannot find module 'npmlog'
    at Function.Module._resolveFilename (module.js:338:15)
    at Function.Module._load (module.js:280:25)
    at Module.require (module.js:364:17)
    at require (module.js:380:17)
    at /usr/lib/node_modules/npm/bin/npm-cli.js:18:11
    at Object.<anonymous> (/usr/lib/node_modules/npm/bin/npm-cli.js:86:3)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)

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Hi guys.

I wrote a little Bash script (That works together with Some Python Scripts)
to help me manage the number of tickets opened to the system administrators team.

When running the script manually, it works perfectly.

However, when I wrapped it into a service unit and a timer unit, something odd happens.
The script runs - I can see the output in the logs. I can hear the sound alert but I don't see the notify window popping up on the screen.

Here is the bash script:
export DISPLAY=":1"
/usr/bin/kill $(/usr/bin/pidof yad) 2>/dev/null
TTIM=$(/home/david/scripts/ # Holds the number of tickets in the mailbox (TIM = Tickets in mailbox)
LTC=$(cat /home/david/scripts/count.txt) #Holds the last ticket count. (LTC = Last Ticket Count)
UTIM=$(/home/david/scripts/ # Holds the number of Unread Tickets in the mailbox

if (( $TTIM < $LTC )) # If the number of tickets in the mailbox is lower than the Last Count, update the last count and check for unread mails.
		echo $TTIM >  /home/david/scripts/count.txt
		if ((  UTIM =0 ))
				echo "There are $TTIM in the mailbox COND 1" >> /home/david/scripts/run.log
				/usr/bin/notify-send "There are no new Tickets! There are $TTIM tickets opened!"
				exit 0
if (( $UTIM > 0 )) #If there are any unread tickets, throw the message anyway!
		echo $TTIM >  /home/david/scripts/count.txt
		/usr/bin/aplay /home/david/scripts/1.wav;
		echo "There are $TTIM in the mailbox 

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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?
Imagine the following scenario:

A NAS box, providing a samba share, with several versions of a fíle collection in dated directories (name i.e. "2017.05.24").

On the NAS should be some links into subdirectories of the latest version, so the copy script should create symbolic links on the share to the latest version of that file collection.

When I try
ln -s <samba_share/link_name> <samba_share/dated_dir_subdir/>

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I get an error that this is not possible. Any hint ?
Hi guys,

Although I find it hard to believe that what I'm looking for even exists, I'll still try my luck.

Is there any Linux Based IDE with native support for bash scripting?
(I don't only mean things like syntax highlighting but also auto completion and etc.) and preferably with git support.

Is there anyway to get a compiled bytecode from a bash script? I know about SHC but it doesn't really help becasue reversing it is way to easy - there's already a ready shell script to reverse the SHC compilation called UNSHC.

what are the best practices and features, options while using grep.

i am using these days to search in log files, files, directories, content etc

When should i give single quote '  '
zgrep 'xyz' aaa.gz

When should i give double quote " "
zgrep "xyz" aaa.gz

how to use tail and head etc along with grep to effectively monitor last or first 100 lines etc
please advise

I keep getting below error when i wrote shell script file and try to open it to.

Swap file "" already exists!
[O]pen Read-Only, (E)dit anyway, (R)ecover, (Q)uit, (A)bort:

why it created .swp file autoatically?
why it asks above question. How to tell unix not to ask that question.
please advise
Free Backup Tool for VMware and Hyper-V
Free Backup Tool for VMware and Hyper-V

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.  

what are differences between
user defined, environmental. local, global variables

when to use which one. what are advanatages, disadvantages of using each with practical examples.
please advise

I like to write a unix shell script to check calendar year, date, current working directory.

how to write and shave .sh file(Say and how to execute to see the output.

Any detailed link explaining these steps with screenshots. please advise

I like to delete matched pattern in a file using vi editor and sed command

i tried as below not working

$ sed 'hello' aaaa.txt :%

please advise
I am trying to build nodejs from source code.

WARNING: C++ compiler too old, need g++ 4.8 or clang++ 3.4 (CXX=g++)
creating ./icu_config.gypi
* Using ICU in deps/icu-small
Using version-specific floating patch tools/icu/patches/58/source/i18n/digitlst.cpp
creating ./icu_config.gypi
{ 'target_defaults': { 'cflags': [],
                       'default_configuration': 'Release',
                       'defines': [],
                       'include_dirs': [],
                       'libraries': []},
  'variables': { 'asan': 0,
                 'coverage': 'false',
                 'debug_devtools': 'node',
                 'force_dynamic_crt': 0,
                 'gas_version': '2.20',
                 'host_arch': 'x64',
                 'icu_data_file': 'icudt58l.dat',
                 'icu_data_in': '../../deps/icu-small/source/data/in/icudt58l.dat',
                 'icu_endianness': 'l',
                 'icu_gyp_path': 'tools/icu/icu-generic.gyp',
                 'icu_locales': 'en,root',
                 'icu_path': 'deps/icu-small',
                 'icu_small': 'true',
                 'icu_ver_major': '58',
                 'node_byteorder': 'little',
                 'node_enable_d8': 'false',
                 'node_enable_v8_vtunejit': 'false',
                 'node_install_npm': 'true',
                 'node_module_version': 48,
                 'node_no_browser_globals': 'false',
                 'node_prefix': '/usr/local',
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.
as per the output below i am getting some waiting for an event.  every time it is stuck at poll As i have limited skills in strace, can some one guide me to find the root cause of the slowness.

munmap(0x7f14322fb000, 4096)            = 0
connect(5, {sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("10.x.x.1")}, 16) = 0
poll([{fd=5, events=POLLOUT}], 1, 0)    = 1 ([{fd=5, revents=POLLOUT}])
sendto(5, ">a\1\0\0\1\0\0\0\0\0\0\trhn1-01-c\5myc\2ca\0"..., 36, MSG_NOSIGNAL, NULL, 0) = 36
poll([{fd=5, events=POLLIN|POLLOUT}], 1, 5000) = 1 ([{fd=5, revents=POLLOUT}])
sendto(5, "\242:\1\0\0\1\0\0\0\0\0\0\trhn1-01-c\myc\2ca\0"..., 36, MSG_NOSIGNAL, NULL, 0) = 36
poll([{fd=5, events=POLLIN}], 1, 4999

[root@ tmp]# strace -e poll yum repolist
Loaded plugins: product-id, search-disabled-repos, security, subscription-manager
poll([{fd=5, events=POLLIN}], 1, 10)    = 1 ([{fd=5, revents=POLLIN}])
poll([{fd=5, events=POLLOUT}], 1, 0)    = 1 ([{fd=5, revents=POLLOUT}])
poll([{fd=5, events=POLLIN|POLLOUT}], 1, 5000) = 1 ([{fd=5, revents=POLLOUT}])
poll([{fd=5, events=POLLIN}], 1, 4999)  = 0 (Timeout)
poll([{fd=6, events=POLLOUT}], 1, 0)    = 1 ([{fd=6, revents=POLLOUT}])
poll([{fd=6, events=POLLIN|POLLOUT}], 1, 5000) = 1 ([{fd=6, revents=POLLOUT}])
poll([{fd=6, events=POLLIN}], 1, 4999)  = 1 ([{fd=6, revents=POLLIN}])
poll([{fd=6, events=POLLIN}], 1, 4999)  = 1 ([{fd=6, revents=POLLIN}])
poll([{fd=6, …
My  VMware machine is not booting.
"vsd-mount                      [!!]
you have entered the recovery shell. the situation you are in may be recoverable.
if you are able to fix this situation the boot process will continue normally after you exit this terminal
/bin/sh: can't access tty; job control turned off"
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
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MVEs are more concerned with the satisfaction of those they help than with the considerable points they can earn. They are the types of people you feel privileged to call colleagues. Join us in honoring this amazing group of Experts.

Hello Folks,

I have a script *.sh That I like to install to few machines (IPs Address), is there anyway anybody can help me write script to do multiples at the same time ?

By the way I'm currently using centos x64

I'd appreciate it and thanks for looking
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.

i have some old unix disks that are on 3.5 and i need to access the data on them, i have loaded up linux and hae been trying to load them but to no success have tried
$ mkdir /mnt/floppy
working through this page
I have the following output i want to write a python code to read only $### and store in a list.

Dining ...2121$15.81
Open Drawer3/14/17
Dining ...2121$5.65
Open Drawer3/14/17
Tim Hortons Tim Hortons
Dining ...2121$5.60
Open Drawer3/11/17
Dining ...2121$8.76
Open Drawer3/11/17
output omitted.
Hi Guys,

Machines on my network recently updated to version 52, which has caused a lot of problems, i managed to get a copy of the 51 deb, but there are one or two machines, when after running "purge firefox" and trying to install version 51 from running dpkg -i firefox.deb it just wont install, if i do apt-get install firefox it works, but only version 52.

I am connecting to these machines over netcat

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