RHCSA: Finding Help
In normal environment Internet is the best medium for finding help. It contains man pages too. In exam environment only man
pages and ISO are available. that mena that you need to study them and compare content of man pages with the books you study for
exam. If examples are available you should try them just to better remember them. In other words the level of jnoledge of the
contnet of man pages correpated with your chances to pass the exam.
Some manpages are convoluted (LVM,grub) and split on dozens of pages descbring individual utilities.
- Change attributes of a Physical Volume.
- Check Physical Volume metadata.
- Initialize a disk or partition for use by LVM.
- Display attributes of a Physical Volume.
- Move Physical Extents.
- Remove a Physical Volume.
- Resize a disk or partition in use by LVM2.
- Report information about Physical Volumes.
- Scan all disks for Physical Volumes.
- Backup Volume Group descriptor area.
- Restore Volume Group descriptor area.
- Change attributes of a Volume Group.
- Check Volume Group metadata.
- Convert Volume Group metadata format.
- Create a Volume Group.
- Display attributes of Volume Groups.
- Make volume Groups unknown to the system.
- Add Physical Volumes to a Volume Group.
- Make exported Volume Groups known to the system.
- Import and rename duplicated Volume Group (e.g. a hardware snapshot).
- Merge two Volume Groups.
- Recreate Volume Group directory and Logical Volume special files
- Reduce a Volume Group by removing one or more Physical Volumes.
- Remove a Volume Group.
- Rename a Volume Group.
- Report information about Volume Groups.
- Scan all disks for Volume Groups and rebuild caches.
- Split a Volume Group into two, moving any logical volumes from one Volume Group to another by moving entire Physical
- Change attributes of a Logical Volume.
- Convert a Logical Volume from linear to mirror or snapshot.
- Create a Logical Volume in an existing Volume Group.
- Display attributes of a Logical Volume.
- Extend the size of a Logical Volume.
- Display the configuration information after loading lvm.conf(5) and any
other configuration files.
- Scan for all devices visible to LVM2.
- Create lvm2 information dumps for diagnostic purposes.
- Reduce the size of a Logical Volume.
- Remove a Logical Volume.
- Rename a Logical Volume.
- Resize a Logical Volume.
- Report information about Logical Volumes.
- Scan (all disks) for Logical Volumes
Some do not produce all the necessary information (yum, grub). Just try to get information about rb.break usage dring
boot (root password recovery procedure):
man -k rb.break
On an average Linux system there are hundreds of commands are available each with dozens of options (way too many to ever be able
to remember all of them). The most basic help system is man pages. During self-study it make sense to use Web version of man pages
are they are cross-referenced with links.
- in addition to man page nearly all commands will display a usage summary if you invoke them with --help option.
The list of options that is shown in this way is of use mainly when you already have a generic understanding of how to use the command
and need a quick overview of options available with the command.
When using the Linux command line, you will at some point consult man pages. Man is what makes working from the command line doable.
If you do not know how a command is used, the man page of that command will provide valuable insight. This section covers a few man
To start with, the most important parts of the man page in general are at the bottom of the man page. Here you’ll find two important
sections: In many cases there are examples; if there are no examples, there is always a “see also” section. This brings you to related
man pages, which is useful if you have just not hit the right man page. To get to the bottom of the man page as fast as possible, use
the G command.
To find information in man pages, you can search the mandb database by using the commands apropos or man
-k. If the database is current, getting access to the information you need is easy. Just type man -k, followed by the
keyword you want to search for. This command looks in the summary of all man pages that are stored in the mandb database.
[[email protected] ~]# man -k partition
addpart (8) - simple wrapper around the "add partition" ioctl
cfdisk (8) - display or manipulate disk partition table
cgdisk (8) - Curses-based GUID partition table (GPT) manipulator
delpart (8) - simple wrapper around the "del partition" ioctl
fdisk (8) - manipulate disk partition table
fixparts (8) - MBR partition table repair utility
gdisk (8) - Interactive GUID partition table (GPT) manipulator
iostat (1) - Report Central Processing Unit (CPU) statistics and in...
kpartx (8) - Create device maps from partition tables
mpartition (1) - partition an MSDOS hard disk
os-prober (1) - Discover bootable partitions on the local system.
partprobe (8) - inform the OS of partition table changes
partx (8) - tell the Linux kernel about the presence and numbering...
pvcreate (8) - initialize a disk or partition for use by LVM
pvresize (8) - resize a disk or partition in use by LVM2
resizepart (8) - simple wrapper around the "resize partition" ioctl
sfdisk (8) - partition table manipulator for Linux
sgdisk (- Command-line GUID partition table (GPT) manipulator fo...
systemd-efi-boot-generator (8) - Generator for automatically mounting the EFI...
systemd-gpt-auto-generator (8) - Generator for automatically discovering and ..
Based on the information that man -k is giving you, you can probably identify the man page that you need to accomplish
whatever you want to accomplish. Be aware, however, that man -k is not perfect; it searches only the short summary of
each command that is installed. If your keyword is not in the summary, you’ll find nothing and get a “nothing appropriate” error message.
While using man -k to find specific information from the man pages, you’ll sometimes really get a lot of information.
If that happens, it might help to filter down the results a bit by using the grep command. But if you want to do that,
it is important that you know what you are looking for.
- Use the command
man -k '' which list all man-page names available
Man pages are categorized in different sections. The most relevant sections for system administrators are as follows:
- 1: Executable programs or shell commands
- 5: File formats and conventions
- 8: System administration commands
There are also sections that provide in-depth detail, such as the sections about system calls and library calls. When using man
-k, you’ll get results from all of these sections. To limit the results that display, it makes sense to use grep
to show only those sections that are relevant for what you need. So, if you are looking for the configuration file that has something
to do with passwords, use man -k password | grep 5, or if you are looking for the command that an administrator would use to
create partitions, use man -k partition | grep 8.
Another useful man option is -f. The command man -f <somecommand> displays a short description of the item
as found in the man database. This may help you when deciding whether this man page contains the information you are looking for.
When using the man -k command, the mandb database is consulted. It can sometimes happen that you are looking for something
that should obviously be documented but you cannot find anything anyway and all you get is “nothing appropriate.” If that happens, you
might need to update the man database. Doing that is easy: Just run the mandb command as root without any arguments.
It will see whether new man pages have been installed and update the man database accordingly.
Tip: Do not try to memorize all the commands that you need to accomplish specific tasks. Instead, memorize how to find these
commands and which man page to read to get more information about the command.
Let’s assume that you are looking for a command, using man -k, but all you get is a message “nothing appropriate” and you
do not remember how to fix it.
Two Party System
as Polyarchy :
Corruption of Regulators :
and Control Freaks : Toxic Managers :
Harvard Mafia :
: Surviving a Bad Performance
Review : Insufficient Retirement Funds as
Immanent Problem of Neoliberal Regime : PseudoScience :
Who Rules America :
: The Iron
Law of Oligarchy :
War and Peace
Finance : John
Kenneth Galbraith :Talleyrand :
Oscar Wilde :
Otto Von Bismarck :
George Carlin :
Propaganda : SE
quotes : Language Design and Programming Quotes :
Random IT-related quotes :
Somerset Maugham :
Marcus Aurelius :
Kurt Vonnegut :
Eric Hoffer :
Winston Churchill :
Napoleon Bonaparte :
Ambrose Bierce :
Bernard Shaw :
Mark Twain Quotes
Vol 25, No.12 (December, 2013) Rational Fools vs. Efficient Crooks The efficient
markets hypothesis :
Political Skeptic Bulletin, 2013 :
Unemployment Bulletin, 2010 :
Vol 23, No.10
(October, 2011) An observation about corporate security departments :
Slightly Skeptical Euromaydan Chronicles, June 2014 :
Greenspan legacy bulletin, 2008 :
Vol 25, No.10 (October, 2013) Cryptolocker Trojan
Vol 25, No.08 (August, 2013) Cloud providers
as intelligence collection hubs :
Financial Humor Bulletin, 2010 :
Inequality Bulletin, 2009 :
Financial Humor Bulletin, 2008 :
Bulletin, 2004 :
Financial Humor Bulletin, 2011 :
Energy Bulletin, 2010 :
Malware Protection Bulletin, 2010 : Vol 26,
No.1 (January, 2013) Object-Oriented Cult :
Political Skeptic Bulletin, 2011 :
Vol 23, No.11 (November, 2011) Softpanorama classification
of sysadmin horror stories : Vol 25, No.05
(May, 2013) Corporate bullshit as a communication method :
Vol 25, No.06 (June, 2013) A Note on the Relationship of Brooks Law and Conway Law
Fifty glorious years (1950-2000):
the triumph of the US computer engineering :
Donald Knuth : TAoCP
and its Influence of Computer Science : Richard Stallman
: Linus Torvalds :
Larry Wall :
John K. Ousterhout :
CTSS : Multix OS Unix
History : Unix shell history :
VI editor :
History of pipes concept :
Solaris : MS DOS
: Programming Languages History :
PL/1 : Simula 67 :
History of GCC development :
Scripting Languages :
Perl history :
OS History : Mail :
DNS : SSH
: CPU Instruction Sets :
SPARC systems 1987-2006 :
Norton Commander :
Norton Utilities :
Norton Ghost :
Frontpage history :
Malware Defense History :
GNU Screen :
OSS early history
Principle : Parkinson
Law : 1984 :
The Mythical Man-Month :
How to Solve It by George Polya :
The Art of Computer Programming :
The Elements of Programming Style :
The Unix Hater’s Handbook :
The Jargon file :
The True Believer :
Programming Pearls :
The Good Soldier Svejk :
The Power Elite
Most popular humor pages:
Manifest of the Softpanorama IT Slacker Society :
of the IT Slackers Society : Computer Humor Collection
: BSD Logo Story :
The Cuckoo's Egg :
IT Slang : C++ Humor
: ARE YOU A BBS ADDICT? :
The Perl Purity Test :
Object oriented programmers of all nations
: Financial Humor :
Financial Humor Bulletin,
2008 : Financial
Humor Bulletin, 2010 : The Most Comprehensive Collection of Editor-related
Humor : Programming Language Humor :
Goldman Sachs related humor :
Greenspan humor : C Humor :
Scripting Humor :
Real Programmers Humor :
Web Humor : GPL-related Humor
: OFM Humor :
Politically Incorrect Humor :
IDS Humor :
"Linux Sucks" Humor : Russian
Musical Humor : Best Russian Programmer
Humor : Microsoft plans to buy Catholic Church
: Richard Stallman Related Humor :
Admin Humor : Perl-related
Humor : Linus Torvalds Related
humor : PseudoScience Related Humor :
Networking Humor :
Shell Humor :
Financial Humor Bulletin,
2011 : Financial
Humor Bulletin, 2012 :
Financial Humor Bulletin,
2013 : Java Humor : Software
Engineering Humor : Sun Solaris Related Humor :
Education Humor : IBM
Humor : Assembler-related Humor :
VIM Humor : Computer
Viruses Humor : Bright tomorrow is rescheduled
to a day after tomorrow : Classic Computer
The Last but not Least Technology is dominated by
two types of people: those who understand what they do not manage and those who manage what they do not understand ~Archibald Putt.
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December 13, 2020