Linux Distributions

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A Linux distribution is an operating system made as a software collection based on the Linux kernel and, often, on a package management system and are available for a variety of systems. A typical Linux distribution comprises a Linux kernel, GNU tools and libraries, additional software, documentation, a window system (the most common being the X Window System), a window manager, and a desktop environment. Most Linux systems are open-source software made available both as compiled binaries and in source code form, allowing modifications to the original software. Over three hundred distributions are in active development, including commercially backed distributions (such as Fedora, openSUSE and Ubuntu) and community-driven distributions (such as Debian, Slackware, Gentoo and Arch Linux).

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I am having trouble trying to delete a file in linux
I have a file that I can see using ls -lrt called events.csv
but when I try to delete I get an error

ls -lrt
total 0
-rwxrwxrwx 0 root root 1048576 Jan 11 14:43 events.csv

sudo rm -rf  events.csv
<< does nothing >> i check back and the file is still there

sudo rm -rv events.csv
<< get error>
rm: cannot remove 'customer-events.csv': No such file or directory
0
Angular Fundamentals
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Angular Fundamentals

Learn the fundamentals of Angular 2, a JavaScript framework for developing dynamic single page applications.

Hi,

I have a security related question on Linux Ubuntu.
Can we remove sudo access to root console for power users.
But still allow admin to ssh to the servers with root password.
As a security measure is it a good idea to disable root access to everyone if  connecting to servers remotely.

Thanks
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"/u11/nfs-server0" is a mount point for an nfs connection.  Redhat v 6.9 apps "du" & "df" counts the nfs mount “/u11/nfs-server0” as local disk consumed.

Here are the examples.
[chill@server0 u11]$ du -h --max-depth=1
121G    ./nfs-server0
207G    ./archive
93G     ./backup
421G    .

[chill@server0 u11]$ df-hP
Filesystem                                Size  Used  Avail  Use% Mounted on
/dev/sda14                                1.0T  421G  552G  44% /u11

Am I correct assuming that file system /u11 actually using only 300 GB of space and has about 675 GB of free space?
What will happened if I attempt to put 600 GB of data on /u11.  Per du/df /u11 would be out of space.
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VirtualBox guest in windows 10, running a 10 GB xUbuntu client. I want to increase to 20 gb. After a lot if work i got the vmdk to 20 gb. But the  "actual size"  in VirtualBox is still only 10 gb. The partition is a vmdk file. (virtual size 20.00 GB, Actual Size 9.07 GB).

No tool i can find can see the file as a partition and increase it from windows, from inside xUbuntu I have the same problem. How can i get the actual size up to 20 GB?

(no i does NOT autoincrease, its just get full)
0
I managed to run docker and install wordpress on ubuntu linux but can't seem to get the handle how I can edit the files within the dock as I get permission issues.
I think I am looking at it the wrong way about,
Could somone get me thinking the right way because  I love the performance for local development :).
(PHP ,Wordpress,MYSQL on NGINX).
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Hi,

I have a NFS server on Ubuntu 16.04 LTS installed on it. The client machine has Windows Home edition , it connects to the server with ovpn which is
on another subnet,
I am unable to mount the NFS share from the client machine .
Kindly guide me how to connect to the NFS share on Ubuntu.

Thanks
0
Hello,

Does anyone have any idea how to authenticate a user against two different OUs on the same AD server?

I am using Apache 2.4 on Ubuntu 18.04.
Server version: Apache/2.4.18 (Ubuntu)
Server built:   2018-06-07T19:43:03

The user could be in "ABC User" or "XYZ user".
AD OUs are:
AuthLDAPURL "ldap://adx.ABC.org:389/OU=ABC Users,DC=ABC,DC=org?sAMAccountName?sub?(objectClass=*)"
and
AuthLDAPURL "ldap://adx.ABC.org:389/OU=XYZ Users,DC=ABC,DC=org?sAMAccountName?sub?(objectClass=*)"


Part of the current conf file:
<Location />
      AuthName "ABC Intranet"
        AuthBasicProvider ldap

        AuthType Basic
        AuthLDAPURL "ldap://adx.ABC.org:389/OU=ABC Users,DC=ABC,DC=org?sAMAccountName?sub?(objectClass=*)"

      # login to AD
      AuthLDAPBindDN "CN=ldap_ABCweb,OU=ABC Service Accounts,DC=ABC,DC=org"
        AuthLDAPBindPassword
        AuthLDAPGroupAttributeIsDN off
        AuthLDAPGroupAttribute memberUid

# tried this and failed
#      Require ldap-filter (&(memberOf='OU=XYZ Users,DC=ABC,DC=org?sAMAccountName?sub?(objectClass=*')|(memberOf='OU=ABC Users,DC=ABC,DC=org?sAMAccountName?sub?(objectClass=*'))

# tried this and failed                                     
#      <RequireAny>
#        Require ldap-filter (&(memberOf='OU=ABC Users,DC=ABC,DC=org?sAMAccountName?sub?(objectClass=*'))
#        Require ldap-filter (&(memberOf='OU=XYZ Users,DC=ABC,DC=org?sAMAccountName?sub?(objectClass=*'))
#       </RequireAny>

      # require any is implied
      require any
      Require valid-user
      …
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Hi Experts,

I'm looking for a simple script to collect the local time drift on Ubuntu Bionic and send it to a specific TCP port in the local system.

Any advice would be highly appreciated.

Thanks & Regards,
Sumedha
0
Hi All,

I am looking to semi-automate the setup of Ubuntu machines.  I don't do that many, so this is more of an 'out of interest' thing than any real productivity issue.

For the avoidance of doubt, I am not looking for a full automated / scripted setup at this point, just to move some setup tasks from being a manual / GUI action to command line.

The first and simple thing is that, when I have setup a new Ubuntu install (16.04 or 18.04), I remove the 'Amazon' icon from the 'favourites' bar.

I do that by right-clicking, and selecting 'remove'.

My underastanding is that I could uninstall Unity Web Apps entirely with this:

sudo apt-get remove unity-webapps-common

Open in new window

which would include the Amazon icon going, but I don't want to remove anything else at this point (unless you think I should?)

I also found a reference that I could run:

sudo apt-get remove ubuntu-web-launchers

Open in new window

to remove the Amazon icon.

My concern is that often there is no explicit mention of what else might be removed or impacted, if anything, which makes me reluctant.

So, how can I just delete the icon from the favourites bar via the command line?


Thanks,

Alan.
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Hi,

With both of the versions of Ubuntu is there a way I can make the favourites bar icons larger. I have found a way to make the other icons larger but not the favourates bar ones.
Happy if there a different way for each version.

Ubuntu 18.04.1 LTS and Ubuntu 18.10

Thanks,

Ward.
0
OWASP: Avoiding Hacker Tricks
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Learn to build secure applications from the mindset of the hacker and avoid being exploited.

Dear Experts, I'm testing Oracle 11g on Centos 7 64b.

I installed Oracle but could not connect to the globalDB by sqlplus, it keeps showing error: ORA-12514: TNS:listener does not currently know of service requested in connect even I start the Oracle Database

ora1.PNG
ora2.PNG
I also attached the response file from Installation process. These are the details of listener and tnsname files:

ora3.PNG
lsnrctl status:

ora4.PNG
Can you please help? Many thanks!
db.rsp
0
Hi

My redhat (guest OS) having issue for not able to resolve the hostname like google.com but able to ping 8.8.8.8.

I didn't do anything at all just to ensure that it can ping Google first and my network subnet like 192.168.1.0/24 when my redhat added a NAT Network adapter without issue.

After that I connect my fortinet vpn client thr IPSec and still can ping and resolve my private cloud thr hostname.

Next day I do the same thing like connect to my iPad 4G network to my Hp laptop wifi.

Can ping and resolved on my hp laptop even being connected to vpn.

The guest os redhat from virtualbox on nat can ping 8.8.8.8 but not able to resolve now.

Why yesterday can and today can't without changing anything?

Thanks.
0
Hello,
I have a FreeBSD and ubuntu server.
I crate a cronjob to execute in specific time. but the command that I do required a full privilege on system... so how I can make the cronjob work with root for example ?
thanks.
0
xhost executing successfully for the user who has the direct login access to the OS.

when I swtich to the other user (su) and which doesn't have the direct login access to OS, could not run the xhost command.

Kindly advice, how to achieve the same.
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I started with asking what the different is between "mode" and "flag", see: https://www.experts-exchange.com/questions/29122213/What-is-the-difference-between-mode-and-flag.html

However, I see that people are using different definitions for a flag. So it's better to start with the question: what is the definition of a flag? I'm not asking for general definitions, or your own definition, but specifically use the definitions in this post (and if necessary correct them and tell me what's wrong about the existing definition).

See: https://techterms.com/definition/flag

In computer science, a flag is a value that acts as a signal for a function or process. The value of the flag is used to determine the next step of a program. Flags are often binary flags, which contain a boolean value (true or false). However, not all flags are binary, meaning they can store a range of values.

Let's start with:

a flag is a value

So apparently, according to this definition, a flag IS a value. So a flag can not be seen as something that be two different values (two different states).

The next sentence confirms that:

Flags are often binary flags, which contain a boolean value (true or false).

Let's say we have c++ std::bitset, but it's about 1 bit. Firstable, it's important to be aware of the difference between:

1. setting the flag
2. setting the bitset

The bitset can be 1 or 0  (in this case because we have one …
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When it's about "flags", I've noticed that different people have different ideas of what a flag is. Some people start to talk about "bit set" when it's about flags. I think the problem lies with the underlaying definitions. It looks like things are not well defined. So for this question, forget about your own ideas/definitions of what a bit set is, just follow the definitions in this post (and change them if necessary). Also forget about flags, this post is specifically about "bitset". First let's start with some "definitions":

See: http://www.cplusplus.com/reference/bitset/bitset/ (std::bitset)

A bitset stores bits (elements with only two possible values: 0 or 1, true or false, ...).

And see: http://www.cplusplus.com/reference/bitset/bitset/set/ (std::bitset::set)

all bits (1)      
bitset& set();
single bit (2)      
bitset& set (size_t pos, bool val = true);

(1) all bits
Sets (to one) all bits in the bitset.
(2) single bit
Sets val as the value for the bit at position pos.

I understand this. But now first let's start at the beginning and let's define a "bit". Let's define it like this:

A bit is an element of two possible binary values: either 0 or 1.

So let's see a bit as a box that contains a ball or a box that doesn't contain a ball. Now let's take a look at a bitset that represents the number 4:

 -----------------------
|0     | 0     |  1     |
|0*2^0 | 0*2^1 |  1*2^2 |
 -----------------------
3 boxes: 
Box 1: no ball
Box 2: no ball
Box 3: ball

Open in new window

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In short, I would say:

A flag is a predefined bit or bit sequence that holds a binary value.

A mode is a distinct setting.

So it's not always possible to replace the term "mode" by "flag". This is only possible if it's about a binary value. I got confused by these terms when reading:

http://man7.org/linux/man-pages/man2/open.2.html

The argument flags must include one of the following access modes:
O_RDONLY, O_WRONLY, or O_RDWR.

The file creation flags are O_CLOEXEC,
O_CREAT, O_DIRECTORY, O_EXCL, O_NOCTTY, O_NOFOLLOW, O_TMPFILE, and
O_TRUNC.

The file status flags are all of the remaining flags listed
below.

Why they just don't say:

The file access flags are O_RDONLY, O_WRONLY, and O_RDWR.

Why they suddenly use a different term when it's about "access"? Probably behind the scenes it's also just about a binary value, right? Probably all O_VARIABLE's above are 0 or 1.

And see: https://en.wikipedia.org/wiki/File_descriptor

This table records the mode with which the file (or other resource) has been opened: for reading, writing, appending, and possibly other modes.

So Wikipedia uses the term "mode" only (and not flag). At least they are consistent, because they call them all "modes".

Is there a specific reason why sometimes mode is used and something flag (while it's about the same thing)? I would stay, be at least consistent to avoid confusion.
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In reality, the "open file table" is not really a table, but let's say we will see it as a table. Which columns does this table have?

For example, see: https://cseweb.ucsd.edu/classes/sp16/cse120-a/applications/ln/lecture15.html

The open file table contains several pieces of information about each file:

the current offset (the next position to be accessed in the file)
a reference count (we'll explain below in the section about fork())
the file mode (permissions),
the flags passed into the open() (read-only, write-only, create, &c),
a pointer to an in-RAM version of the inode (a slightly light-weight version of the inode for each open file is kept in RAM -- others are on disk), and a structure that contains pointers to all of the .
A pointer to the structure containing pointers to the functions that implement the behaviors like read(), write(), close(), lseek(), &c on the file system that contains this file. This is the same structure we looked at last week when we discussed the file system interface to I/O devices.

So according to this, I would say:

- offset
- reference count
- file mode (permission)
- the flags passed into the open() (read-only, write-only, create, &c),
- pointer to in-RAM inode
- pointer to "read(), write(), close(), lseek(), &c".

But the file descriptor also points to the open file table, so we need another column that connects the "file descriptor table" with the "open file table". So I would add a column like:
0
I get a black screen when I am trying to install Manjaro 17 from USB onto my Asus tower, G20aj Processor Intel® Core™ i5-4460 CPU @ 3.20GHz, 3201 Mhz, 4 Core(s), 4 Logical Processor(s). . ( had the same issue in Ubuntu, but thought the different loader Manjaro and Arch might make a difference but it hasn’t.)  The problem seems to lie with the Asus video drivers as I can install just fine on my Alienware/Dell and my HP Spectre.
On the Ubuntu side I found posts talking about some commands to run to get around this issue like aspci and quiet splash, etc. I am not sure where to enter commands or how.  

What I have been doing is boot the computer with install USB and go to the Manjaro OS install line press “e” and then go to the line beginning “Linux/boot/vmlinux-$2” at the end of that line place my commands like  acpi_enforce_resources=lax acpi_osi=Linux acpi_osi=’!Windows 2012’ acpi=force pcie_aspm=force
and then hit F10?

Nothing seems to work.  I have been working on the Manjaro forum but have come to a bit of deadend.
0
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Redirecting output ([n]>[|]word), when does "n" greater than 2 make sense?

This question is about redirecting output in bash, see: https://www.gnu.org/software/bash/manual/html_node/Redirections.html#Redirecting-Output

The general format for redirecting output is:

[n]>[|]word

I already understand the basics (you're just redirecting a file descriptor to a file for writing). But, can someone give me an example when it does make sense to use for example: 3>. In other words, if n is greater than stdin, stdout, stderr (>2), for what would you need it?

I can do:

echo 'test' 3> test-file.txt

Open in new window


This will not write anything to "test-file.txt". This is logical, because now there is just a file descriptor with number 3 pointing to test-file.txt for writing, but there is no input to fd=3 so there is also nothing to write.

The only way to give it some input is to connect file descriptor 3 for reading with a file (or connect it to the output of a pipe). But if you would do that, then fd 3 doesn't point to test-file.txt anymore. So then in the end, fd 3 was connected to test-file.txt without any reason.

So in what kind of situation it's useful to use >n with n greater than 2?
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Ubuntu graphics crash with Visiontek / AMD Radeon 7750

I have a frustrating and consistent issue with gpu crashes on a pair of brand new systems I just built, both used as Ubuntu-based securities trading and data analysis systems.  Any help or ideas in solving this is greatly appreciated.  In all cases, the system boots perfectly fine and performs as expected until a gpu hang, anywhere from a few minutes to around 24 hours later with an average time to gpu hang of around 8 hours.  Degree of system usage from zero to maximum does not seem to affect time to gpu hang.  Upon gpu hang, the screen freezes, but the mouse can still be moved and non-graphics functionality generally continues, such as music playing.  In all cases, a gpu hang is noted in the sys logs, as shown below.

Each of the two systems has the following brand new hardware:

Intel i7-7820X 8 Core Processor
128GB GSkill Ram
Asus Prime X299A Motherboard
Mushkin 2TB SSD
Corsair RM1000x 1000-watt power supply
Corsair Hydro H115i liquid cooler
VisionTek Radeon 7750 2GB 6x-MiniDP Video Card (#900614)  
   (one video card is brand new, the other is two years old, both identical)
No overclocking used
1 to 3 monitors attached

I have run each of these systems with the following Ubuntu OS / configuration combinations as I worked through trying to solve this Radeon crash issue.  Each produces the same consistent gpu hang / crash as described above:

1.  Ubuntu 18.04.1, default configuration, open …
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Ssh struck on local version string for rhel6
0
Dear Wizards, I setup the ubuntu 16.04 server in vSphere 6.5 with 250 GB hard disk, but days later I increased it to 500 GB, but seems like the VM still had only 250 GB.

How can I claim it back correctly? Many thanks!

ired1.PNG
ired2.PNG
0
Logging seems to have stopped.  

I have a DNS server (Slave)...usually go to /var/log/named.log and view the following files:
general.log  lame-servers.log  named.log  named.run  query.log  query.log.0  query.log.1  security.log  transfer.log  update.log

to do a real-time view   i use:

tail -f query.log    to view my current queries.      

Seems to have just stopped....any idea how to get it running again?
0
Hi,

I'm running CentOS Linux release 7.4.1708 (Core), issue is i'm able to login using local users but not using ldap users, please help me on this.

I've tried restarting services using authconfig-tui command, but still i'm getting authentication failure error for ldap user.

please see the attached doc (ldap issue.docx), and below output commands and let me know if any other details are required.


[root@server01 log]# cat /etc/openldap/ldap.conf
#
SASL_NOCANON    on
URI ldap://<ldap servrer ip>:389/
BASE dc=prod,dc=hclpnp,dc=com
#
[root@server01 log]# getent passwd testuser
testuser:*:123456:7001:testuser:/home/testuser:/bin/bash
[root@server01 log]#


[hubba@servder01 ~]$ su - testuser
Password:
su: Authentication failure



[root@server01 log]# cat /etc/nsswitch.conf
#
# /etc/nsswitch.conf
#
# An example Name Service Switch config file. This file should be
# sorted with the most-used services at the beginning.
#
# The entry '[NOTFOUND=return]' means that the search for an
# entry should stop if the search in the previous entry turned
# up nothing. Note that if the search failed due to some other reason
# (like no NIS server responding) then the search continues with the
# next entry.
#
# Valid entries include:
#
#       nisplus                 Use NIS+ (NIS version 3)
#       nis                     Use NIS (NIS version 2), also called YP
#       dns                     Use DNS (Domain Name Service)
#       files              …
0

Linux Distributions

27K

Solutions

20K

Contributors

A Linux distribution is an operating system made as a software collection based on the Linux kernel and, often, on a package management system and are available for a variety of systems. A typical Linux distribution comprises a Linux kernel, GNU tools and libraries, additional software, documentation, a window system (the most common being the X Window System), a window manager, and a desktop environment. Most Linux systems are open-source software made available both as compiled binaries and in source code form, allowing modifications to the original software. Over three hundred distributions are in active development, including commercially backed distributions (such as Fedora, openSUSE and Ubuntu) and community-driven distributions (such as Debian, Slackware, Gentoo and Arch Linux).