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.

Share tech news, updates, or what's on your mind.

Sign up to Post

SYSTEM
Ubuntu Linux 16.04
Android Phone

BACKGROUND
We are on the floor of a convention and trying to connect our linux machine to our Android hot spot. There are too many WiFi hotspots and we cannot find the one from our phone.

QUESTION
On our Linux machine, how to find the hotspot that is being generated by our Android phone? Is there a way to search for the specific hotspot name? Is there a way to turn off the other 100 or more hotspots that are filling up the queue?
0
Python 3 Fundamentals
LVL 12
Python 3 Fundamentals

This course will teach participants about installing and configuring Python, syntax, importing, statements, types, strings, booleans, files, lists, tuples, comprehensions, functions, and classes.

I need to copy a file from one Ubuntu server to another.

They are two servers in the same AWS VPC and are in the same Public Subnet. They are both running Ubuntu (Ubuntu 14.04.5 LTS and Ubuntu 18.04.1 LTS, respectively).

I've opened up the Security Group for BOTH Server using Port 22. I also confirmed that openSSH is running by using this command "ps -A | grep sshd" and seeing process ID's.

I created a Text file for testing.

Here's the command I used to copy between servers:

scp ubuntu@**.*.**.***:/usr/local/thomtesttext.txt ubuntu@**.*.**.***:/usr/local/testtext.txt

Open in new window


This is the error I'm seeing:
ssh: connect to host **.*.**.*** port 22: Connection timed out

Open in new window


What am I doing wrong? How can I get an AWS Ubuntu Server to copy files between them?

Thanks for your help!
0
Have 2 ubuntu installations on Oracle VM. They are in the same version. I ran the same python script against its own ubuntu in the exactly same way. Ran well on one, but got the error on the other one below:
"ModuleNotFoundError: No module named 'x'".
I knew the one without error was installed more packages, but I did not remember which more packages were installed. Under this condition, how to troubleshoot this issue? Can any gurus shed some light to it? Thanks a lot.
Background:
ubuntu 18.04 on VirtualBox V5.2.22 in Windows 7 (2 Ubuntus installed on the same box).
0
Have a sizeable on-line application in php on Virtual Box Ubuntu and like to understand it completely. Would like to use some debug tools to know what is going on which page to corresponding to the code behind it. Can any gurus shed some light to it: recommend some tools to debug and understand the code? Thanks a lot.
0
I need to backup a Ubuntu 18.04 server. I use Storage Craft for all backups but they do not have anything that can backup that version of Linux. I need to find a product that can backup that server.

I am not a Linux tech so I would prefer something where I can install the backup agent on Linux and manage it from a Windows server. I also want it to backup the entire image of the server so I can restore it if necessary.

Can someone recommend a good product for that. Preferable one that is not expensive
0
I'm a IT / Music Composition double major.

At school we use PHP a lot.

I want to start learning Node.js and express, at least the basics to get familiar with it.

The operating system I run on my laptop is Ubuntu 18.04.

How can I run both Node and PHP on my laptop?

------
0
I am running Ubuntu 14.04.5 LTS in Amazon Web Services with an Elastic IP and an inbound connection for my Static IP.

I need to simply copy files from Ubuntu (Ubuntu 14.04.5) to my local mac (running OS 10.14.2) and then copy them back, both using a Terminal window and SSH.

I've tried scp, but can't seem to get the command correct as the error I'm getting is:

"ssh: connect to host **.*.**.*.** port 22: Connection timed out" (This IP is the Elastic IP).

What am I doing wrong? Help! Thanks in advance. :-)
0
zgrep -C5 'xyz' abc.gz

i have above grep
in the results how to search on say "error code=1111 description=null pointer"


Above results too large i am not able to copy paste to notepad++ (which i usually do makes easy to to my eyes) to search on like error code=1111 description=null pointer"

zgrep -C5 'xyz' abc.gz >>/home/TestUser/testuser.txt

can we do tail or head on above?
please advise
0
Hello there,

I want to restart my java application which is running on Ubuntu 16.04 as service. But the problem I have is on Ubuntu when I want to restart my java application service, I do as follows
sudo service myapp restart

Open in new window

and then Ubuntu asks for password. Now how can I tell Ubuntu to not ask password when I send this cmd from my application.

//Restart application server
		router.get("/restartAppService").handler(ctx -> {
			/* Build command: sudo service AooService stop */
			  final ArrayList<String> command = new ArrayList<String>();
			  command.add("sudo service TutisService restart");
			  System.out.println("CMD ----"+command.toString());
			  final ProcessBuilder builder = new ProcessBuilder(command);
			  	try {
			  		builder.start();
				} catch (IOException e) {
					System.out.println("EXCEPTION WHILE RESTARTING SERVICE----"+e.getMessage());
					e.printStackTrace();
				}
			  //System.exit(0);
		});

Open in new window


Any help will be appreciated!!

cheers
Zolf
0
I'm looking to use apt-get for Ubuntu and yum for Centos to do the following as root:

1) Ubuntu: apt-get update ; apt-get -d dist-upgrade
to just download the update items for later install

2) How do I install the previously downloaded files at a different time? I was thinking apt-get -f install but can't tell if t will get all the updates. - my 2 Ubuntu systems are both up to date so I can't test this yet

3) yum for CentOS doesn't seem to have a download only option. This part of the question is not as critical.

Thanks in advance
0
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.

i am using mputty to connect to unix box.

i see black screen with while log messages

i like to change to white bacground screen with black letter on top

please advise
0
Are there instructions somewhere for setting up VPN on Ubuntu via command line?

Anyone can provide any reference please?  Thank you!!
0
MY SYSTEM
Ubuntu Linux 18.04.1

QUESTION
I need to know what is the best recommended Anti-Virus and Malware protection I can install on my Linux machine.
Please include: Free, Less Expensive, and the Best (no matter what the price), so I can make my decision.
0
We have Ubuntu 18.04.1 LTS running on a virtual machine in VMWare Workstation 12.5.7 build-5813279.

The network settings appear to be correct however every time we boot it we get the grey icon with the question mark.  We can disable the network and reenable it and everything is fixed.  Can you tell me how to fix this issue as it is rather annoying?
0
When updating composer (sudo composer update), got the error below:
"- The requested PHP extension ext-memcached * is missing from your system. Install or enable PHP's memcached extension."
Tried very hard to install "PHP extension ext-memcached", but could not get anywhere.
Background: PHP 7.2.10-0ubuntu0.18.04.1 (cli) (built: Sep 13 2018 13:45:02) ( NTS ) on oracle VirtualBox v5.2.22.

Will any gurus shed some light to it?
0
Hi,

I'm new to Azure and am having issues with my test Ubuntu VM - I am unable to get outbound internet access. I have been trying for a few hours to get this to work and am now completely stuck.

I have gone through the following steps:

The VM has a private IP, which is statically assigned in Azure but acquired using DHCP on the OS.
The network security group that is attached to the network interface allows outbound internet access.
There is no security group defined on the subnet.
There are no custom route tables on the subnet.
To remove DNS from the equation, I also tried to ping an IP address (8.8.8.8).

Can anyone think of something I've missed?

Thanks,
Adrian
0
i have removed below pid file using rm command as i got some error messages with permissions on that

rm xyz.pid

is there is a way i can restore that file

I am trying to start the web logic server and having issues which used to work earlier file

Please advise
0
to run below script to start web logic
/opt/scripts/bea_start admin
after login i cannot directly execute
i have to go to below directory to execute

cd /xyz/home/user123/opt/def/bea_domains/12/xyz_dev1/servers/xyz_dev1_admin/logs

i though below is absolute path and as soon as i login i should be able to run from
/opt/scripts/bea_start admin

also i have to run as admin only not as my user id

why i cannot run as soon as i login from root directory(if i am not mistaken that is what i go as soon as i login)

also how to see who all can run the script and how to change that script permission so that even if i login i can execute not just admin

Please advise
0
zgrep 'MobileDevice' xyz_1.log.20181121.gz|grep 'USER123'| awk '$0>= "2018-Nov-21 00:01" && $0<="2018-Nov-21 23:59"' | awk -F '|' '$24>300 {print}'

zgrep 'MobileDevice' xyz_2.log.20181121.gz|grep 'USER123'| awk '$0>= "2018-Nov-21 00:01" && $0<="2018-Nov-21 23:59"' | awk -F '|' '$24>300 {print}'

zgrep 'MobileDevice' xyz_3.log.20181121.gz|grep 'USER123'| awk '$0>= "2018-Nov-21 00:01" && $0<="2018-Nov-21 23:59"' | awk -F '|' '$24>300 {print}'

i am using above 3 separate greps one after other on 3 types of jvm files

how to combine them as one

zgrep 'MobileDevice' xyz_?.log.20181121.gz|grep 'USER123'| awk '$0>= "2018-Nov-21 00:01" && $0<="2018-Nov-21 23:59"' | awk -F '|' '$24>300 {print}'
i tried above which did not work
i tried below that also did not work


zgrep 'MobileDevice' xyz_*.log.20181121.gz|grep 'USER123'| awk '$0>= "2018-Nov-21 00:01" && $0<="2018-Nov-21 23:59"' | awk -F '|' '$24>300 {print}'
please advise
0
Bootstrap 4: Exploring New Features
LVL 12
Bootstrap 4: Exploring New Features

Learn how to use and navigate the new features included in Bootstrap 4, the most popular HTML, CSS, and JavaScript framework for developing responsive, mobile-first websites.

Hi,



 while adding ubuntu to vitual box after removing centos there getting attached error
i am using windows 10 hp laptop currently


please advise how resolve this error.



thanks in advance
ERRuBUNTU.png
0
zgrep 'xyz'  abc.log.2018111212| grep '|[1-9][0-9][0-9][0-9][0-9]|0000' | wc -l

i am trying to figure out what above grep doing?

what is meaning of
|[1-9][0-9][0-9][0-9][0-9]|0000

wc -l means some kind of word count?
what is -l

any good links or resources or video tutorials to master greps and awk and sed end to end to debug server logs?

please advise
0
https://www.opencsw.org/packages/CSWclamav/

From above url, seems like we can't download ClamAV for
Solaris x86 directly : had to use the command:
  pkgadd -d http://get.opencsw.org/now
  /opt/csw/bin/pkgutil -U
  /opt/csw/bin/pkgutil -y -i clamav

I don't have a Solaris box that internet facing.

Anyone has the package?
0
Our RHEL 6  DB server does not have Internet access, thus we can't do 'yum'.

We would like to temporarily install ftp server (guess it's called vsftpd) :
how can we go about doing this?  Give step by step instruction including
where to get vsftpd rpm package (& its dependent packages if any).

Also provide the exact commands (guess it's  'rpm -ivh ./folder_of_RPMs' )

We can download to a laptop & use laptop to sftp over the RPMs.
0
Actually the file descriptor table is not a real table. It's just an array of pointers to the "open file table" (struct file). But let's say we will see it as a table. What are the columns? For example:

FD   | Pointer to "open file table"
----------------------------------
...  | ...

In short, that's the question. I see a lot of different figures on the internet, but they are all different. For example, see:

http://faculty.winthrop.edu/dannellys/csci325/10_shared.htm
There they have a column "fd flags" (read/write), but I would think that this column is part of the "open file table" and not part of the "file descriptor table". See for example: http://man7.org/linux/man-pages/man2/open.2.html


       A call to open() creates a new open file description, an entry in the
       system-wide table of open files.  The open file description records
       the file offset and the file status flags (see below).  A file
       descriptor is a reference to an open file description; this reference
       is unaffected if pathname is subsequently removed or modified to
       refer to a different file.  For further details on open file
       descriptions, see NOTES.

       The argument flags must include one of the following access modes:
       O_RDONLY, O_WRONLY, or O_RDWR.  These request opening the file read-
       only, write-only, or read/write, respectively.
0
My Tomcat web application logs are telling me the user1 isn't in the specified mapped LDAP role/group coming from AD. I believe my issues lie with the JNDI Realm definition. Can someone review it please and see where I may be going wrong, I've included the DN information from AD as well:

My user1 account DN is

DistinguishedName : CN=user1,OU=Users,OU=Lab,DC=example,DC=com

Open in new window


The role/group Users I have specified in the web.xml config is

DistinguishedName : CN=Users,CN=Builtin,DC=example,DC=com

Open in new window


My Realm configuration is

<Realm
   className="org.apache.catalina.realm.JNDIRealm"
   debug="99"
   connectionURL="ldap://example.com:389"
   authentication="simple"
   referrals="follow"
   connectionName="cn=administrator,cn=users,dc=example,dc=com"
   connectionPassword="##########"
   userSearch="(sAMAccountName={0})"
   userBase="cn=users,dc=example,dc=com"
   userSubtree="true"
   userRoleName="memberOf"
   roleSearch="(member={0})"
   roleName="cn"
   roleSubtree="true"
   roleBase="cn=users,cn=builtin,dc=example,dc=com"/>

Open in new window

0

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.