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 have a C# program that runs perfectly under Windows 10.  It uses Connected Services so that I can add in additional Class and Method functions to connect to Ultimate Software's HR system and pull our employee information from.  What I would like to do is run this application under Linux CentOS.  I installed Mono for Linux on both CentOS 6 and CentOS 7; and verified 100% that it can and does run compiled Visual Studio C# programs under Linux.  No problem.

However, when I run the EXE program under Linux Mono, it does not connect to the external website defined in Connected Services.

Here is the line it is failing on.

loginClient = new LoginServiceClient("WSHttpBinding_ILoginService");

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And the error I get back, is (of course), a NullReferenceException as the defined object of 'loginClient' never gets instantiated.

System.NullReferenceException: Object reference not set to an instance of an object.

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Has anyone ever successfully taken an EXE file for Windows using Connected Services and run it under Linux Mono?

Thank you,
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Determine the Perfect Price for Your IT Services

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Hi Team,

I have a folder /opt/reports

In this folder I have some log files for the past 2 years  , I need to list the log files created between 01-03-2015 to 11-03-2015 and 01-03-2016 to 11-03-2016 ,  I tried with find command I was not successful . Is there any other way to get the output . I just need to list the files .

find /opt/reports -name "DatabaseServer" -ctime 720 -print , Iam trying to manupilate the creation time , but not getting the output



In my Output  I must get the below files and exclude all files creatred before 1 st of march and after 11 th of march 2015 and 2016
Need help on setting permissions for a directory, new to linux.

I have a folder /opt/reports

I have users called user1 , user2  who loggin into linux and  read the contents of the files in this directory. I want to give read permission only to this user1 and user2 and rwx for others users.
Any help in this regard is really appreciated.
Ubuntu Linux 16.04
Android Phone

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.

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?
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

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

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

Thanks for your help!
Hi, I need help building PHP 7.3.0 with module with WebP support on a Linux server RHEL 7.6. I tried running
yum install make gcc plesk-php73-devel libjpeg-turbo-devel libpng-devel libXpm-devel freetype-devel libwebp-devel

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but libwebp-devel is not available from subscription-manager.

Please help!


Good Day,

I'm new to Linux, could you please guide me which is the best and secure Linux os (Freeware)

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.
ubuntu 18.04 on VirtualBox V5.2.22 in Windows 7 (2 Ubuntus installed on the same box).
This is using SuSE Enterprise Server 11 with SP4. We are intend to update the OS Kernel to the latest version. Please see the current version as follows,

#uname -v
MP Fri Jul 15 14:30:41 UTC 2016 (eb2ba81)

#uname -r

The latest os kernel version is, 3.0.101-108.1. Shall we manually downloading these latest kernel rpm and then run "rpm -Uvh" to update it? or using zypper?

I heard that is best to "install" this latest version, and then choose to booting up the system with this latest version while kept those older vesion. Yes, the second intention is, keep the older version, so as we can roll back to use the older version if this latest version causes problem.

By the way, how to update the os kernel, and then do the roll back if needed?

Thanks in advance.
This is using SuSE Enterprise server 11 with Service Pack 4. Please see the configure zypper repositories for updates, patches as follows,

#zypper lr -u

Refreshing service 'spacewalk'.
#  | Alias                                            | Name                                             | Enabled | Refresh | URI                                      
 1 | SUSE-Linux-Enterprise-Server-11-SP4_11.4.4-1.109 | SUSE-Linux-Enterprise-Server-11-SP4 11.4.4-1.109 | Yes     | No      | iso:///?iso=SLES-11-SP4-DVD-x86_64-GM-DVD1.iso&url=file:///mnt/iso/
 2 | samba_upd                                        | samba_upd                                        | Yes     | No      | dir:///kk                                
 3 | spacewalk:sle11-hae-sp4-pool-x86_64              | SLE11-HAE-SP4-Pool for x86_64                    | Yes     | Yes     | plugin:spacewalk?channel=sle11-hae-sp4-pool-x86_64&server=0
 4 | spacewalk:sle11-hae-sp4-updates-20160920         | SLE11-HAE-SP4-Updates-20160920                   | Yes     | Yes     | plugin:spacewalk?channel=sle11-hae-sp4-updates-20160920&server=0
 5 | spacewalk:sle11-sdk-sp4-pool-x86_64              | SLE11-SDK-SP4-Pool for x86_64                    | No      | Yes     | plugin:spacewalk?channel=sle11-sdk-sp4-pool-x86_64&server=0
 6 |…
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I need to enable GD to regenerate some thumbnails on an Apache 2.4 Amazon Linux Php-FPM system.  I used Yum and it appears to have installed but it isn't enabled.

I am running php-fpm and my PHP version is 7.2.

Please tell me how to enable GD or a comparable package to regenerate the thumbnails for my WooCommerce site.

what is the perl regular expresssion to compare "machinename\\username" in perl scripts?

sample code:
print "Hello World!\n";
$user = "test";
$mu_reg = "^(?i)$mname/\/\$user \$";
$mu_str = "164AUTH/\/\chris";

$ipstr="$mu_str ";
$ipstr_re = "^(?i)mu_reg \$"; # regex failed with two backslashes. How to fix it?
if ($ipstr !~ /$ipstr_re/) {
    print "It doesn't match\n";
else {
    print "It matches\n";
Hello, I'm in need of some assistance to compile PHP module with WebP support on my server.

I started following the instruction provided here:

The original instructions refer to PHP version 7.1.11 however, I changed mine to 7.2.13 which is the current version on my Plesk Server.

This is the result of the first 2 commands so far, and I had to stop because I saw the packages required were not available. I didn't want to continue because I don't want to break my current PHP version, but I need PHP module with WebP support on my server.

Could somebody please take a look and give me so guidance? Should I continue?

yum install make gcc plesk-php72-devel libjpeg-turbo-devel libpng-devel libXpm-devel freetype-devel libwebp-devel


[root@web ~]# yum install make gcc plesk-php72-devel libjpeg-turbo-devel libpng-devel libXpm-devel freetype-devel libwebp-devel
Loaded plugins: product-id, search-disabled-repos, subscription-manager
This system is not registered with an entitlement server. You can use subscription-manager to register.
PLESK_17_8_11-extras                                                                                                                                       | 2.9 kB  00:00:00    
PLESK_17_PHP52                                                                         …
I have a linux system that I use which is regularly getting filled by by these /var/tmp/sos directories.
They seem to be getting created every week and taking 10s of gigs of space. Is this a normal part of
linux operation? It's causing the disk to become critically full too often. Is there a way to automatically
delete the old sos directories?

Also - do you know if the directories systemd-private-* need to be kept and what generates them?

observium tmp]$ ls -l
total 24
-rw-r--r--. 1 root   root      0 Dec 27 20:15 need_home_synced
-rw-r--r--. 1 nagios nagios    6 Dec 28 09:16 retrans_state.txt
drwx------. 2 root   root   4096 Dec 28 04:13 sos.t92dy0
drwx------. 2 root   root   4096 Dec 21 03:35 sos.y5KVwk
drwx------. 3 root   root   4096 May 17  2018 systemd-private-04196687cdcc41d2be170a72a0dcb5fc-httpd.service-b7fs9F
drwx------. 3 root   root   4096 May 17  2018 systemd-private-04196687cdcc41d2be170a72a0dcb5fc-mariadb.service-HPqubD
drwx------. 3 root   root   4096 May 17  2018 systemd-private-04196687cdcc41d2be170a72a0dcb5fc-ntpd.service-A5CYzA

Linux 3.10.0-514.10.2.el7.x86_64 #1 SMP Fri Mar 3 00:04:05 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
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.
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
Utilziing RunTime Live boot ISO right.  Does this utility have the ability to write 1s to hard drive?   I want to format and write over any preexisting data.   What's the best boot ISO utility for that?  Please provide directions if not an easy to (point and click) perform task.
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?

Hello All,
when running the below python script from the terminal to change an interface MAC, I get the following message: "siocsifhwaddr cannot assign requested address"

any ideas of what could be happening?

#!/usr/bin/env python

import subprocess

interface = "eth0"
new_mac = "11:22:33:44:55:11"
print("[+] Changing MAC for " + interface + " to " + new_mac)"ifconfig " + interface + " down", shell=True)"ifconfig " + interface + " hw ether " + new_mac, shell=True)"ifconfig " + interface + " up", shell=True)

Learn Ruby Fundamentals
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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. :-)
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
Using the below code in the bash script, i get the list of the available interface names.
How can i assign each found interface name to different variables, then use them to configure each interface name.

Thank you For your great help and Quick Prompts
(if you know a better way to find the existing interface names. please share ;)  )

ifconfig -a | sed 's/[ \t].*//;/^\(lo\|\)$/d'

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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

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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 {
				} catch (IOException e) {
					System.out.println("EXCEPTION WHILE RESTARTING SERVICE----"+e.getMessage());

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Any help will be appreciated!!

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
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






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.