CentOS has numerous advantages over some of the other clone projects including an active and growing user community, quickly rebuilt, tested, and QA’ed errata packages, an extensive mirror network, developers who are contactable and responsive, multiple free support avenues including IRC Chat, Mailing Lists, Forums, a dynamic FAQ.

The following operating systems are now available for all VPS hosting packages:

• Debian 4.0 (Etch)
• Debian 5.0 (Lenny)
• Ubuntu 7.04 (Feisty Fawn)
• Ubuntu 8.04 LTS (Hardy Heron)
• CentOS 5.1

Currently all of our operating system versions come as a bare install.  What that means is we do not pre-install anything other than what it takes to get your server up and running.  Not is this method more secure, it allows you to configure the server exactly how you need it.

If you have no idea what change management is, you need it more than you think. Basically, Change Management helps ensure that standardized methods and procedures are used for efficient and prompt handling of all changes to controlled IT infrastructure, in order to minimize the number and impact of any related incidents upon service.

Change Management is required to conform with PCI Data Security Standard 6.4. In addition a standardized change management policy increases productivity. Requirement 6.4 requires change control procedures for all system and software configuration changes. The following PCI standards are met by this module:

6.4.1 Documentation of impact.

6.4.2 Management sign-off by appropriate parties.

6.4.3 Testing of operational functionality.

6.4.4 Back out procedures.

This service is free for any VPS or dedicated server hosted at ZZ Servers.  Be warned in advance though, this is a beta release.

To access your dashboard, go to https://www.zzservers.com/dashboard/.

This vulnerability only affects operating systems which (like Ubuntu) are based on Debian. However, other systems can be indirectly affected if weak keys are imported into them. We consider this an extremely serious vulnerability, and urge all users to act immediately to secure their systems.

The following Ubuntu releases are affected:

• Ubuntu 7.04
• Ubuntu 7.10
• Ubuntu 8.04 LTS
• Debian Etch 4.0
• Debian Lenny 5.0

For more details visit these links:

• Ubuntu: http://www.ubuntu.com/usn/usn-612-2
• Debian: http://www.debian.org/security/2008/dsa-1571

We consider this an extremely serious vulnerability, and urge all users to act immediately to secure their systems.

With the advent of multiple core processors and Xen, it is possible to virtualize an entire data center and fit 50 or more independent servers into one Xen server.  There are a number of third-party tools or known as management consoles have been developed to facilitate the common tasks of administering a Xen host, such as configuring, starting, monitoring and stopping of Xen guests. Examples include Enomalism, Xen Tools, Google’s Ganeti, MLN, HyperVM, FluidVM, ConVirt (formerly XenMan) and Red Hat’s Virtual Machine Manager, virt-manager.  Unfortunately, all of them fall short in one area or another in a distributed, secure and automated environment.

I will not get into how each of these management programs work but with few exceptions, they require complex installations into the Domain-0 or privileged domain and require incoming connections to it, or require a local desktop tool.  While this is convenient, it is not completely secure and can potentially lead to vulnerabilities.  If Domain-0 is ever compromised, all other guest domains running in it are vulnerable as well.  As a basic for security, the following should be required:

1. Run the smallest number of necessary services on Domain-0.

2. Use a firewall to restrict the traffic Domain-0.

3. Do not allow users to access Domain-0.

4. Do not allow any incoming connections to Domain-0.

So, How do you manage a Xen server remotely if you cannot directly access Domain-0 you say?  The answer is almost too simple, Domain-0 will use outgoing connections to a remote server.  This not only allows the server to be more secure, it can potentially reduce memory and load requirements of the management domain.

Currently, we have working scripts that can provision and manage guest domains as well as send statistics to a remote server.  These scripts are only just beginning but are currently working in a production environment.  Each are released using GPL licensing in hopes that others will gain some use and provide feedback so we can make managing xen servers easier and more secure.

The IT Governance Data Breaches Report identifies that spectacular data breaches, such as the UK’s HMRC CD-Rom fiasco and the prolonged theft of TK Maxx credit card records, are not caused by the misdemeanor of a junior employee but arise, rather, from systemically inadequate information security arrangements at the organizations where the incident occurs.

A data breach is ‘the unauthorized disclosure by an organization of personally identifiable information, where that disclosure compromises the security, confidentiality, or integrity of the data that has been disclosed.’

The Attrition database shows that the numbers of reported data breaches in the US increased from 22 in 2004 to 326 in 2006. The pattern in the UK and elsewhere is similar. Three developments in recent years make addressing this issue a real priority:

1. Identify theft is a low-risk, high return option for organized crime. Traditional crime, including violent robbery and theft, has clearly identifiable risks. It is easy to be recorded on video by CCTV, seen by witnesses or caught by means of DNA, and the returns are relatively low. High-tech crime, on the other hand, creates real problems for the police force and is, conversely, relatively low-risk for the criminal. Contributing factors include the perpetrator’s anonymity, the speed at which crimes can be committed, the volatility or transience of evidence, the trans-jurisdictional nature of cybercrime and the high costs of investigation.

2. Legal and regulatory compliance initiatives, such as the EU Data Protection directive and California’s data breach disclosure law, SB1386, have both formalized the concept that personal data must be legally protected, and introduced penalties for failing to do so.

3. The proliferation of mobile data storage devices has changed the boundaries of where we store our data and effectively eliminated "fixed fortifications" as an effective tool for preventing data breaches.

The number of data breaches reported both within the US and the UK has been steadily increasing since 2006. In the US, the introduction of California’s data breach disclosure law, SB1386, in July 2003 led to a greater awareness of data breaches and, as a consequence, greater reporting of them. Within the UK, the numbers of reported data breaches has also been steadily rising, with a large increase in the number of reported data breaches following the HMRC breach. The peaks in reported data breaches following the disclosure of the UK’s HMRC data loss, suggests that there were - and probably still are - many data breaches that go unreported and research suggests that organizations are reluctant to officially report data breaches unless they have already been exposed. The evidence suggests that waiting to be found out is not the best strategy.

12% of reported breaches in the UK were at regulated financial services organizations. Those reported in the unregulated private sector are much lower. An extrapolation from this behavior is that the likely scale and cost of data breaches in this sector in the UK is probably much bigger than has actually been reported - and at least as great as that in the public and regulated sectors.

The reported number of internally caused data breaches remains lower than external ones, but averages to around a third of those reported each year since 2000. Many data breaches are self-inflicted in that organizations adopt confidentiality regimes that make it difficult for people to actually do their job and, as a result, they bypass controls with unpredictable but inevitable data breach consequences.

The Ponemon report commented that "the investment required to prevent a data breach is dwarfed by the resulting costs of a breach" and " the return on investment (ROI) and justification for preventative measures is clear". Costs of data breaches - legal costs, the costs of restitution, brand damage, lost customers and so on - are significant; for financial services organizations, it was about £55 per compromised record.

Whilst not involving legal compliance, if an organization has a credit card-related data breach and is found not in compliance with the Payment Card Industry Data Security Standard (PCI DSS), there are potentially severe contractual and financial penalties, including a bar on the business accepting payment cards.

All these factors make the protection of personal data a key business and compliance responsibility; the information security management standard ISO27001 provides a best-practice specification for an information security management system that would meet the requirements of the Data Protection Act 1998.

The most important steps for Data Protection Act compliance are:

As a minimum:

1. Encrypt all personal data on laptops; whole disk encryption is a more secure solution than folder or file level encryption, and FIPS 140-2 is the recognized standard for encryption engines.

2. Encrypt all removable and portable media that might contain personal data, including USB drives, CD-Roms and magnetic backup tapes.

In addition:

3. Establish rigorous procedures to ensure the physical destruction of redundant computer drives, magnetic media and paper records prior to disposal, and ensure that disposals are made in line with a formal data retention timetable.

4. Organizations that accept credit and other payment cards should also comply with the PCI DSS.

5. Provide regular training and awareness on legal responsibilities for all staff that deal with personal data.

6. Deploy outward-bound channel (email, instant messenger) filtering software with customized dictionaries for relevant legislation such as DPA, PCI, etc

7. Establish a vulnerability patching program and implement anti-malware software.

8. Implement a business-driven access control policy, combined with effective authentication.

9. Develop an incident management plan that enables the organization to respond effectively to any data breaches.

Data Breaches Report
ISO27001
PCI DSS

Article Source: http://EzineArticles.com

- rw- r– r– other information about the file Filename

The initial - signifies that this is a file (not a directory). The next three characters refer to the file permissions for the file owner, in many cases the person who created the file. The values rw- signify that the owner has read and write (modify) permission but not execute permission. Had these values been r-x the owner would be able to read and execute the file (program) but not modify it. The second set of values r– signify that the members of the group associated with this file have read but not write or execute permission. The third set of values also r– signify that other users have read but not write or execute permission.

Permissions are often handled numerically. The r has a value of 4, the w has a value of 2, and the x has a value of 1. In all cases the lack of permission has the value 0. So rw- has the value 6 and r– has the value 4. In the above example the permissions may be expressed as 644. The full set of permissions for everyone is expressed as 777 (not usually a good idea).

Note that the root user’s permissions aren’t listed. This shouldn’t be surprising because root has essentially complete permissions. But even root’s doesn’t have execute permissions for a file it creates. This permission must be added in a separate step. Why? This two-step procedure has important security implications. Let’s say that someone, perhaps root, has received an email that contains a virus-infested executable program. The program cannot be executed without the explicit permission of root or the recipient. If the user doesn’t know what to do the virus won’t be launched.

Linux defines permissions for directories that are similar to but not exactly the same as the file permissions. A read permission on a directory means that its contents may be listed. A write permission on a directory means that the user can modify its contents, by adding, deleting, or renaming files. An execute permission on a directory means that it may be accessed, in other words made the current working directory.

Permissions may be changed via the chmod command as in the example chmod 770 Junque which gives read, write, and execute permissions to the file owner and members of the ownership group but no permissions to anyone else. Not everyone likes working with these numbers. The symbolic mode uses letters and the plus and minus signs to change permissions.

The following command removes the write permission from the user (owner) of the Perm file chmod u-w Perm. To add the execute permission for others, people who do not belong to the group that owns the file apply the command chmod o+x Perm This command only makes sense if the Perm file is executable. Furthermore, under most circumstances the file owner and his or her group will have more permissions that the others. Linux doesn’t always check to see that your command really makes sense. Do you think that Windows is more intelligent in this respect?

The chown command is used to change the ownership of a file or a directory. The chgrp command is used to change the group ownership of files and directories. These commands might be used when a project passes from the development to the testing stage. Needless to say only the system administrator can execute these commands.

Of course there is more to Linux permissions and groups but we have covered the basics. The next article in this series discusses inodes, a topic that is sorely missing from the Windows bag of tricks.

Levi Reiss has authored or co-authored ten books on computers and the Internet. He loves the occasional glass of wine as exemplified by his wine websites including http://www.theworldwidewine.com. He teaches Linux and Windows operating systems plus other computer courses at an Ontario French-language community college. Visit his new website http://www.linux4windows.com which teaches you how to download and run Damn Small Linux on Windows computers, even if they are "obsolete."

Article Source: http://EzineArticles.com

• Apache 2 - Linux Web server
• MySQL 5 - MySQL Database Server
• PHP4/5 - PHP Scripting Language
• phpMyAdmin - Web-based database admin software.

Note: Linux + Apache + MySQL + PHP/Perl together commonly known as LAMP Server.

First, let us prepare a system that has a minimum requirement of Debian/Ubuntu version of Linux with at least 256MB of RAM available. Anything less than this minimum ram will cause lot of problems since we are running a server along especially MySQL and Webmin requires lots of RAM to run properly. MySQL will give you this nasty error “cannot connect to mysql.sock” if you don’t have enough memory in your server.

I love Debian/Ubuntu based Linux because of my enormous affinity towards this command apt-get. As a starter knowing this one command, It is so easy to install packages and you don’t need to worry about package dependency and configuration. You need to buy a dedicated server or a VPS package if you want to setup your own server. If you want to experiment with the server and installation it is recommended to buy a VPS package. Believe it or not it is so easy to install and configure your server yourself even though you are new are to Linux and dedicated/VPS hosting.

First download PuTTy if you are accessing your server through SSH. Just enter the IP of your server with root login to access your host. As you probably know, Webmin is a freely available server control panel and we will setup this once we have completed the LAMP server and Mail Server. Webmin makes more easier for us to fine tune our Linux box.

Before proceeding to install, update the necessary packages with Debian with this command.

apt-get install update

1. Installing Apache + PHP

Apache is one of the most famous web server which runs on most Linux based servers. With just few commands you can configure apache to run with PHP 4 or PHP 5.

If you want to install PHP 4, just apt-get

apt-get install apache2 php4 libapache2-mod-php4

To install PHP5, just run the following on Linux shell. Note that if you don’t specify packages with ‘4′, PHP5 will be automatically installed.

apt-get install apache2 php5 libapache2-mod-php5

Apache configuration file is located at: /etc/apache2/apache2.conf and your web folder is /var/www.

To check whether php is installed and running properly, just create a test.php in your /var/www folder with phpinfo() function exactly as shown below.

vi /var/www/test.php

# test.php
<?php phpinfo(); ?>

Point your browser to http://ip.address/test.php or http://domain/test.php and this should show all your php configuration and default settings.

You can edit necessary values or setup virtual domains using apache configuration file.

2. Installing MySQL Database Server

Installing mysql database server is always necessary if you are running a database driven e-commerce site. Remember running MySQL server to a fair extend requires at least 256mb of RAM in your server. So unless you are running database driven sites you don’t absolutely need MySQL. The following commands will install MySQL 5 server and MySQL 5 client.

apt-get install mysql-server mysql-client php5-mysql

Note: If you have already installed php4, you should make a slight change like this.

apt-get install mysql-server mysql-client php4-mysql

The configuration file of MySQL is located at: /etc/mysql/my.cnf

Creating users to use MySQL and Changing Root Password

By default mysql creates user as root and runs with no passport. You might need to change the root password.

To change Root Password

mysql -u root

mysql> USE mysql;

mysql> UPDATE user SET Password=PASSWORD(’new-password’) WHERE user=’root’;

mysql> FLUSH PRIVILEGES;

You must never use root password, so you might need to create a user to connect to MySQL database for a PHP script. Alternatively you can add users to MySQL database by using a control panel like Webmin or phpMyAdmin to easily create or assign database permission to users. We will install Webmin and phpMyAdmin during later once we complete basic installation.

3. PhpMyAdmin Installation

PhpMyAdmin is a nice web based database management and administration software and easy to install and configure under apache. Managing databases with tables couldn’t be much simpler by using phpMyAdmin.

All you need to do is:

apt-get install phpmyadmin

The phpMyAdmin configuration file is located at: /etc/phpmyadmin folder.

To set up under Apache all you need to do is include the following line in /etc/apache2/apache2.conf:

Include /etc/phpmyadmin/apache.conf

Now restart Apache:

/etc/init.d/apache2 restart

Point your browser to: http://domain/phpmyadmin

That’s it! MySQL and phpMyAdmin are ready. Log in with your mysql root password and create users to connect to database from your php script.

This tutorial was written by Scott who currently runs MySQL-Apache-PHP.com.

Use cat to output the contents of this file (see Concatenating Text).

* To output the release name of the Debian system you are on, type:

$ cat /etc/debian_version

NOTE: Debian releases have historically been named after characters from the motion picture Toy Story.

arch

Outputs the processor architecture.

$ arch

i686

cat

Outputs the contents of a file.

$ cat lorem.txt

Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

cd

Change the working directory.

$ cd /bin

chgrp

Change group ownership of files.

$ chgrp games moo.txt

chmod

Change access permissions of files.

$ chmod +x helloworld

chown

Change file owner and group.

# chown root lorem.txt

cksum

Print CRC checksum and byte counts of each file.

$ cksum lorem.txt moo.txt

3570240675 453 lorem.txt

4294967295 0 moo.txt

cp

Copies a file.

$ cp lorem.txt copy_of_lorem.txt

date

Outputs the current date and time.

$ date

Sat Mar 3 12:07:09 GMT 2007

df

Reports the amount of disk space used and available on filesystems.

$ df

Filesystem 1K-blocks Used Available Use% Mounted on<br>

/dev/simfs 39845888 218048 39627840 1% /

dir

List directory contents.

$ dir

copy_of_lorem.txt lorem.txt moo.txt www

du

Estimate file space usage.

$ du -h /bin

7.8M /bin

echo

Display a line of text.

$ echo foobar

foobar

exit

Cause the shell to exit.

$ exit

fgrep

Print lines matching a pattern in a file.

$ fgrep “irure dolor” lorem.txt

commodo consequat. Duis aute irure dolor in reprehenderit in voluptate

find

Search for files in a directory hierarchy.

$ find hello*

hello_world

hello_world.c

free

Display amount of free and used memory in the system.

$ free

total used free shared buffers cached

Mem: 8299892 8287708 12184 0 2641772 1731236

Low: 3581300 3572764 8536

High: 4718592 4714944 3648

-/+ buffers/cache: 3914700 4385192

Swap: 8193140 2335664 5857476

grep

Print lines matching a pattern.

$ grep -i apple fruitlist.txt

apple

groups

Outputs the user groups of which your account belongs to.

$ groups

games users

head

Output the first part of files.

$ head -2 lorem.txt

Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod

tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim

hostname

Outputs the machines hostname on the network.

$ hostname

anapnea.net

id

Outputs user id, group id, and groups of your account.

$ id

uid=1478(smallfoot) gid=100(users) groups=35(games),100(users)

kill

End a process.

$ kill -9 18298

-bash: kill: (18298) - Operation not permitted

killall

Kill processes by name.

$ killall irssi

irssi(18298): Operation not permitted

irssi(13372): Operation not permitted

irssi(22048): Operation not permitted

irssi: no process killed

last

Show listing of last logged in users.

$ last -n 3

alice pts/6 192.0.34.166 Fri May 18 16:17 still logged in

bob pts/2 64.233.183.103 Fri May 18 16:17 still logged in

clare pts/6 72.5.124.61 Fri May 18 15:54 - 15:55 (00:01)

ldd

Print shared library dependencies.

$ ldd /bin/bash

libncurses.so.5 => /lib/libncurses.so.5 (0×40023000)

libdl.so.2 => /lib/libdl.so.2 (0×40065000)

libc.so.6 => /lib/libc.so.6 (0×40069000)

/lib/ld-linux.so.2 (0×40000000)

ln

Make links between files.

$ ln -s data.txt symlink.txt

logname

Print user’s login name.

$ logname

smallfoot

ls

List directory contents.

$ ls

copy_of_lorem.txt lorem.txt moo.txt www

man

Opens the manual page for a software or function.

$ man bash

md5sum

Outputs the MD5 hash sum of a file.

$ md5sum lorem.txt

56da9e37259af34345895883e6fd1a27 lorem.txt

mkdir

Makes a directory.

$ mkdir foobar

mv

Moves a file.

$ mv lorem.txt ipsum.txt

nl

Number lines of files.

$ nl lorem.txt

1 Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod

2 tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim

3 veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea

4 commodo consequat. Duis aute irure dolor in reprehenderit in voluptate

5 velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint

6 occaecat cupidatat non proident, sunt in culpa qui officia deserunt

7 mollit anim id est laborum.

nm

List symbols from object files.

$ nm hello_world

080494a0 D _DYNAMIC

0804956c D _GLOBAL_OFFSET_TABLE_

08048474 R _IO_stdin_used

w _Jv_RegisterClasses

08049490 d __CTOR_END__

0804948c d __CTOR_LIST__

08049498 d __DTOR_END__

…

od

Dump files in octal and other formats.

$ od -t x /bin/sh

2376640 00098020 000054d4 00000000 00000000

2376660 00000020 00000000 000000c7 00000008

2376700 00000003 080e6500 0009d4f4 00004ae8

…

pidof

Find the process ID of a running program.

$ pidof fetchmail

22392

ping

Pings a host.

$ ping -c 2 127.0.0.1

PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data.

64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.048 ms

64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.052 ms

— 127.0.0.1 ping statistics —

2 packets transmitted, 2 received, 0% packet loss, time 999ms

rtt min/avg/max/mdev = 0.048/0.050/0.052/0.002 ms

ps

Outputs running processes.

$ ps

PID TTY TIME CMD

21542 pts/12 00:00:00 bash

27706 pts/12 00:00:00 ps

pstree

Display a tree of processes.

$ pstree

init-+-2*[BitchX]

|-3*[bash---sleep]

|-fetchmail

|-screen-+-bash—irssi

| `-bash—ctorrent

|-screen-+-bash—lisp.run

| |-bash—vi

| |-2*[bash]

| `-bash—lynx

|-2*[screen---bash---irssi]

|-screen—irssi

|-screen—bash

|-screen-+-bash

| `-irssi

|-skjerm—irssi

|-sshd-+-5*[sshd---sshd---bash---irssi]

| |-8*[sshd---sshd---bash]

| |-sshd—sshd—bash—screen

| |-sshd—sshd

| `-sshd—sshd—bash—pstree

`-syslog-ng

pwd

Outputs the name of current working directory.

$ pwd

/home/smallfoot

rm

Removes a file or directory.

$ rm lorem.txt

rmdir

Removes a directory.

$ rmdir foobar

sed

Stream editor for filtering and transforming text.

$ echo “My cat’s name is Bob” | sed -e ’s/Bob/Mittens/g’

My cat’s name is Mittens

sha1sum

Outputs the SHA1 hash sum of a file.

$ sha1sum lorem.txt

c942ddebd142ec8bacac9213d48096e74bab4957 lorem.txt

shutdown

Bring the system down in a secure way. All logged-in users are notified that the system is going down.

$ shutdown now

size

List section sizes and total size.

$ size /bin/bash

text data bss dec hex filename

621233 22712 19176 663121 a1e51 /bin/bash

stat

Outputs file status.

$ stat lorem.txt

File: `lorem.txt’

Size: 453 Blocks: 8 IO Block: 4096 regular file

Device: 77h/119d Inode: 27312217 Links: 1

Access: (0644/-rw-r–r–) Uid: ( 1478/smallfoot) Gid: ( 100/ users)

Access: 2007-03-03 12:24:39.000000000 +0000

Modify: 2007-03-03 12:24:39.000000000 +0000

Change: 2007-03-03 12:24:39.000000000 +0000

strings

Print the strings of printable characters in files.

$ strings hello_world

/lib/ld-linux.so.2

_Jv_RegisterClasses

__gmon_start__

libc.so.6

puts

_IO_stdin_used

__libc_start_main

GLIBC_2.0

PTRh%

[^_]

Hello World!

tail

Output the last part of files.

$ tail -2 lorem.txt

occaecat cupidatat non proident, sunt in culpa qui officia deserunt

mollit anim id est laborum.

talk

Talk to another user.

$ talk bob Lookout for the dopefish!

touch

Change a file’s access and modification timestamps. If file does not exist, create it.

$ touch lorem.txt

tty

Outputs the name of the current terminal.

$ tty

/dev/pts/16

uname

Outputs operating system, hostname, kernel version, date and timp, and processor.

$ uname -a

Linux anapnea.net 2.6.9 #1 SMP Wed Jul 19 16:24:18 MSD 2006 i686 Intel(R) Xeon(TM) CPU 2.80GHz GenuineIntel GNU/Linux

uptime

Outputs the system uptime.

$ uptime

14:50:26 up 7 days, 17:52, 18 users, load average: 0.08, 0.02, 0.01

users

Print the user names of users currently logged in to the current host.

$ users

alice bob charlie eve

vdir

List directory contents.

$ vdir

total 8

-rw-r–r– 1 smallfoot users 453 Mar 3 12:32 copy_of_lorem.txt

-rw-r–r– 1 smallfoot users 453 Mar 3 12:24 lorem.txt

-rw-r–r– 1 smallfoot users 0 Mar 3 12:32 moo.txt

lrwxr-xr-x 1 root root 18 Feb 27 19:33 www -> /var/www/smallfoot

w

Show who is logged on and what they are doing.

$ w

12:14:30 up 5 days, 15:16, 19 users, load average: 0.00, 0.00, 0.00

USER TTY LOGIN@ IDLE JCPU PCPU WHAT

charlie pts/0 Fri21 3:26m 2.52s 2.52s irssi

alice pts/2 Wed17 30:21m 0.00s 0.00s -bash

emma pts/4 11:37 36:57 0.00s 0.00s -bash

frank pts/5 11:48 11:03 0.00s 0.00s -bash

smallfoo pts/12 12:01 0.00s 0.04s 0.01s w

wall

Send a message to everybody’s terminal.

$ wall next week we change the server for a new one

wc

Counts lines in a file.

$ wc -l lorem.txt

7 lorem.txt

whatis

Search the whatis database for complete words.

$ whatis bash

bash (1) - GNU Bourne-Again SHell

bash [builtins] (1) - bash built-in commands, see bash(1)

who

Outputs who is currently logged into the system.

$ who

charlie pts/0 Mar 2 21:37 (xtreme-11-65.acme.com)

alice pts/2 Feb 28 17:48 (147.21.16.3)

emma pts/4 Mar 3 11:37 (32.84-48-181.uac.com)

frank pts/5 Mar 3 11:48 (port-212-202-233-2.foobar.org)

smallfoot pts/12 Mar 3 12:01 (c-12776f4.cust.example.net)

whereis

Locate the binary, source, and manual page files for a command.

$ whereis bash

bash: /bin/bash /etc/bash /usr/share/man/man1/bash.1.gz

whoami

Outputs your username / the name of your account.

$ whoami

smallfoot

find <PATH> -print | xargs grep "<CONTENT>"

or

find <PATH> -type f -exec grep -H "<CONTENT>" \;