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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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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
JavaScript Best Practices
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JavaScript Best Practices

Save hours in development time and avoid common mistakes by learning the best practices to use for JavaScript.

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
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
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
how to enable xhost in Linux server

I am  getting the below error
xhost +
xhost:  unable to open display "10.1.1.1:0"

==
please advise
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 …
0
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.
0
Amazon Web Services
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Amazon Web Services

Are you thinking about creating an Amazon Web Services account for your business? Not sure where to start? In this course you’ll get an overview of the history of AWS and take a tour of their user interface.

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
unix server keep sign out after 1 minute or so on production.

is there is a way i can run some process like

tail -f xyz.gz
to keep continuous rolling until i cancel that so that it wont sign out on me while i focus on some other work  for 30 miinutes and come back it should not signout
please advise
0
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?
0
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 …
0
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
how to grep multiple awks

$ awk '{print;}' employee.txt
100  Thomas  Manager    Sales       $5,000
200  Jason   Developer  Technology  $5,500
300  Sanjay  Sysadmin   Technology  $7,000
400  Nisha   Manager    Marketing   $9,500
500  Randy   DBA        Technology  $6,000


$ awk '{print $2,$5;}' employee.txt
Thomas $5,000
Jason $5,500
Sanjay $7,000
Nisha $9,500
Randy $6,000

in above query how to tweak to see  see all records whose name starts with 'S' and Salary greater than '6000'

also
in above query how to tweak to see  see all records whose name starts with 'S' and Salary greater than '6000' and Department Starts with  'T'


100  Thomas  Manager    Sales       $5,000     08/08/1988 6:00:01AM
200  Jason   Developer  Technology  $5,500 08/08/1989 7:00:02AM
300  Sanjay  Sysadmin   Technology  $7,000 08/08/1982 9:00:03AM
400  Nisha   Manager    Marketing   $9,500 08/08/1981 10:00:04AM
500  Randy   DBA        Technology  $6,000 08/08/1981 11:00:5AM
if it has joined date and time as above
in above query how to tweak to see  see all records whose name starts with 'S' and Salary greater than '6000' and Department Starts with  'T' and joined between particular date time to particular date time say  08/08/1982 9:00:03 AM till 08/08/1981 10:00:04AM
i need to use above in a zgrep command

https://www.thegeekstuff.com/2010/01/awk-introduction-tutorial-7-awk-print-examples/
0
awk query
 unzip -c  xyz.log.20180905.gz| awk '$0>= "2013-Sep-09 18:33" && $0 <="2013-Sep-09 23:15"'| grep '|[1-9][0-9][0-9][0-9][0-9]|0000'|wc -l
Zip file too big (greater than 4294959102 bytes)
  End-of-central-directory signature not found.  Either this file is not
  a zipfile, or it constitutes one disk of a multi-part archive.  In the
  latter case the central directory and zipfile comment will be found on
  the last disk(s) of this archive.
how to learn awk any good video tutorials on it?
please advise
0
CompTIA Security+
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Learn the essential functions of CompTIA Security+, which establishes the core knowledge required of any cybersecurity role and leads professionals into intermediate-level cybersecurity jobs.

zgrep 'XYZ|AB|MASTER' AAAA.log.20180904.gz | grep '|[1-9][0-9][0-9][0-9][0-9]|0000' | wc -l

can you please advise what is the meaning of above zgrep command

where i can find, practice and learn above kind of commands

how grep and egrep are different

https://ryanstutorials.net/linuxtutorial/grep.php
how to learn regular expressions used in queries

Please advise
0
data no align after i do cat in unix this is my script
cat data*.txt|grep -v ^UNIT_CDE|awk '{print $1,",",$2,",",$3,","$4,",",$5,",",$6,",",$7,",",$8,",",$9,","$10,",",$11,",",$12,",",$13,",",$14,",",$15,","$16,",",$17,",",$18,",",$19,",",$20}' >>  mergetstneg.txt
catfileimg.jpg
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
file create error on below site


https://www.tutorialspoint.com/execute_bash_online.php

please advise how to create some files and practice grep commands there

any other online free tools to practice unix.

please advise
fileCreate.png
0
I have created several ipsets broken up by country.  I need to list the names of the ipsets I have built and I need to know how to have the ipsets persist after a reboot.  I am on a Linux 2 Amazon Apache 2.4 instance.
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).