|By Mark R. Hinkle||
|August 12, 2005 04:00 PM EDT||
Fedora Core (http://fedora.redhat.com) is one of the world's most popular Linux distributions in part from support by Red Hat and a strong community of users. It also has been a proving ground for Red Hat to develop technologies that will eventually make their way into Red Hat Enterprise Linux.
Recently Red Hat has spun off the Fedora Core Project into its own organization in much the same way that the Mozilla project was spun out of Netscape back in the late 1990s. Both Fedora and Red Hat Enterprise Linux have proven to be raging successes in their own right for both Red Hat and Linux users who choose to pursue a do-it-yourself approach to Linux. For those of you looking for additional resources to learn more about these distributions, you could consider the Red Hat Fedora and Enterprise Linux 4 Bible written by Christopher Negaus.
Christopher Negus has been working with UNIX systems, the Internet, and (most recently) Linux systems for more than two decades at AT&T Bell Laboratories, UNIX System Laboratories, and Novell, helping to develop the UNIX operating system. Features from many of the UNIX projects Chris worked on at AT&T have found their way into Red Hat Enterprise Linux, Fedora, and other Linux systems. Chris has written several books on UNIX and the Internet; his latest book is the Red Hat Fedora and Enterprise Linux 4 Bible (excerpted below) and released in July 2005. It discusses the features and capabilities of both operating systems. His book is written as a resource for users trying to adopt either of these technologies.
With your Fedora Core system connected to the Internet, you can take advantage of dozens of tools for browsing the Web, downloading files, getting e-mail, and communicating live with your friends. In most cases, you have several choices of GUI and command-line applications for using Internet services from your Linux desktop or shell. However, there are some utilities you may not be familiar with like wget, scp, and sftp.
Excerpt from Chapter 9...
Getting Files with wget
If you already know where a file is on the network, there are more efficient ways of downloading that file than opening an FTP session, moving around the FTP server, and running the get command. The wget command is a simple, efficient tool for doing non-interactive downloads of files over the Internet.
If there is a file you want to download from an FTP site or Web server (HTTP), and you know exactly where the file is, wget is a good way to download. The wget command is very useful if you want to copy a whole site, recursively, from one computer to another (for example, containing user home directories). When downloading from FTP sites, wget can let you just download as the anonymous user or add your own user name and password to the command line.
Downloading a File with User Name and Password
If you are doing an FTP file copy and need to log in as a user other than anonymous, you can add that information to the command line or to a .netrc file in your home directory (type man netrc to see the format of that file). Here is an example of adding the password to the command line:
CAUTION: Adding a password to a command line leaves the password exposed to onlookers. This practice is generally discouraged, except in cases where no one can see your monitor or your history files.
In the previous example, the user logs in as joe with the password my67chevy. The wget then copies the file memo1.doc from the current directory on the host computer named ftp.handsonhistory.com. That current directory is most likely /home/joe.
Downloading a Whole Web Site
Using wget, you can download a large number of files from Web servers as well. The wget command downloads files using the http protocol, if file addresses begin with http://. Downloading a single file, you would use the same form as you would for an FTP file (for example: wget http://host/file.). The best wget option for HTTP downloads is -r (recursive).
A recursive download lets you choose a point at a Web site and download all content below that point. Here is an example of a recursive download used to download the contents of the www.example.com Web site.
$ wget -r http://www.example.com
In this example, the HTML pages, images, and other content on the www.example.com Web site are copied below the current directory in the directory www.example.com. This is useful if you want to gather the contents of a Web site but don't have login access to that site. Because content is taken by following links, if there is content in a directory at the Web site that isn't in a link, it won't be downloaded.
Downloading an entire Web site can result in a massive amount of data being downloaded. If you want only part of a Web site, start from a point lower in the site's structure. Or, as an alternative, you can limit the number levels the wget will go down the site structure. Using the -l option (l as in level), the following example gets two levels of HTML content:
$ wget -r -l 2 http://www.example.com
To mirror a site, you can use the -m option instead of -r. With wget -m http://site, it is like asking to download an infinite number of levels recursively (-r -l inf), keep current time stamps (-N), and keep FTP directory listings (-nr).
Continuing a Download
In the old days, if you were downloading a particularly large file (such as an ISO image of a CD or DVD), if the download stopped for some reason (a disconnected network or errant reboot), you needed to start all over. With wget, you can choose to restart a download and have it continue right where it left off. This has been a lifesaver for me on many occasions.
Let's say that you were downloading a 4GB DVD ISO image named mydvd.iso from the site ftp://ftp.example.com and you killed the wget process by mistake after about 3GB of download. Make sure that your current directory is the one that contains the partially downloaded ISO. Then run the same wget command you did originally, adding the -c (continue) option as follows:
$ wget -c ftp://ftp.example.com/mydvd.iso
If you had not used the -c option, in this case, a new download would have started using the file name mydvd.iso.1 to download to.
NOTE: Another command that you might be interested in, similar to wget, is the curl command. Like wget, curl can download files using the ftp or http protocols. Curl can also do multiple file transfers on the same connection.
After you typed the password in the preceding case, the last several lines of the /var/log/messages file on the remote computer would be displayed. As messages were received, they would continue to be displayed until you decided to exit (press Ctrl+C to exit the tail command).
NOTE: Find out more about the ssh command from the SSH Web site (www.openssh.org).
Using scp for Remote File Copy
The scp command is a simple yet secure way of copying files among Linux systems. It uses the underlying ssh facility, so if ssh is enabled, so is scp. Here is an example of using scp to copy a file from one computer to another:
# scp myfile toys.linuxtoys.net:/home/chris
[email protected]'s password: ******
In this example, the file myfile is copied to the computer named toys.linuxtoys.net in the /home/chris directory. If you don't provide a user name (as is the case here), scp assumes you are using the current user name. Unlike some tools that provide remote login, scp and ssh do allow you to login as root user over the network, by default. (Many people turn off this feature for security reasons.)
To use scp with a different user name, you can append the user name with an @ character. For example, [email protected]:/home/chris would attempt to log in as the user named chris to do the file copy.
The first time you connect to a remote computer using scp or ssh, those commands try to establish the authenticity of the remote host. If it cannot establish the host's authenticity, it will display the RSA key fingerprint and ask you if you want to continue. If you type yes, scp will not question the authenticity of that computer again for subsequent scp commands.
However, if the RSA key fingerprint should change in the future for the remote computer (which will happen if, for example, the operating system is reinstalled on that computer), scp will refuse to let you connect to that remote computer. To override that refusal, you need to edit your $HOME/.ssh/known_hosts file and delete the entry for the remote computer. You can then verify the authenticity of the remote computer and continue to use scp.
The sftp command, which also communicates using secure ssh protocols, is a command for copying files from an FTP server. It is considered a more secure way of getting files from an FTP server that has an sshd server running.
You can receive more helpful tips on using Fedora and Red Hat Enterprise Linux 4 in Chris's book, Red Hat Fedora and Enterprise Linux 4 Bible available at your local retailer.
SYS-CON Events announced today that Commvault, a global leader in enterprise data protection and information management, has been named “Bronze Sponsor” of SYS-CON's 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Commvault is a leading provider of data protection and information management solutions, helping companies worldwide activate their data to drive more value and business insight and to transform moder...
Sep. 25, 2016 06:15 PM EDT Reads: 2,371
Fact is, enterprises have significant legacy voice infrastructure that’s costly to replace with pure IP solutions. How can we bring this analog infrastructure into our shiny new cloud applications? There are proven methods to bind both legacy voice applications and traditional PSTN audio into cloud-based applications and services at a carrier scale. Some of the most successful implementations leverage WebRTC, WebSockets, SIP and other open source technologies. In his session at @ThingsExpo, Da...
Sep. 25, 2016 05:30 PM EDT Reads: 1,535
SYS-CON Events announced today that Bsquare has been named “Silver Sponsor” of SYS-CON's @ThingsExpo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. For more than two decades, Bsquare has helped its customers extract business value from a broad array of physical assets by making them intelligent, connecting them, and using the data they generate to optimize business processes.
Sep. 25, 2016 04:15 PM EDT Reads: 2,548
Almost two-thirds of companies either have or soon will have IoT as the backbone of their business in 2016. However, IoT is far more complex than most firms expected. How can you not get trapped in the pitfalls? In his session at @ThingsExpo, Tony Shan, a renowned visionary and thought leader, will introduce a holistic method of IoTification, which is the process of IoTifying the existing technology and business models to adopt and leverage IoT. He will drill down to the components in this fra...
Sep. 25, 2016 03:00 PM EDT Reads: 1,573
The vision of a connected smart home is becoming reality with the application of integrated wireless technologies in devices and appliances. The use of standardized and TCP/IP networked wireless technologies in line-powered and battery operated sensors and controls has led to the adoption of radios in the 2.4GHz band, including Wi-Fi, BT/BLE and 802.15.4 applied ZigBee and Thread. This is driving the need for robust wireless coexistence for multiple radios to ensure throughput performance and th...
Sep. 25, 2016 02:30 PM EDT Reads: 1,508
SYS-CON Events announced today that Pulzze Systems will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Pulzze Systems, Inc. provides infrastructure products for the Internet of Things to enable any connected device and system to carry out matched operations without programming. For more information, visit http://www.pulzzesystems.com.
Sep. 25, 2016 02:15 PM EDT Reads: 1,798
Enterprise IT has been in the era of Hybrid Cloud for some time now. But it seems most conversations about Hybrid are focused on integrating AWS, Microsoft Azure, or Google ECM into existing on-premises systems. Where is all the Private Cloud? What do technology providers need to do to make their offerings more compelling? How should enterprise IT executives and buyers define their focus, needs, and roadmap, and communicate that clearly to the providers?
Sep. 25, 2016 02:00 PM EDT Reads: 1,514
SYS-CON Events announced today that SoftLayer, an IBM Company, has been named “Gold Sponsor” of SYS-CON's 18th Cloud Expo, which will take place on June 7-9, 2016, at the Javits Center in New York, New York. SoftLayer, an IBM Company, provides cloud infrastructure as a service from a growing number of data centers and network points of presence around the world. SoftLayer’s customers range from Web startups to global enterprises.
Sep. 25, 2016 01:00 PM EDT Reads: 826
There is little doubt that Big Data solutions will have an increasing role in the Enterprise IT mainstream over time. Big Data at Cloud Expo - to be held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA - has announced its Call for Papers is open. Cloud computing is being adopted in one form or another by 94% of enterprises today. Tens of billions of new devices are being connected to The Internet of Things. And Big Data is driving this bus. An exponential increase is...
Sep. 25, 2016 12:45 PM EDT Reads: 2,457
Digital innovation is the next big wave of business transformation based on digital technologies of which IoT and Big Data are key components, For example: Business boundary innovation is a challenge to excavate third-party business value using IoT and BigData, like Nest Business structure innovation may propose re-building business structure from scratch, as Uber does in the taxicab industry The social model innovation is also a big challenge to the new social architecture with the design fr...
Sep. 25, 2016 12:15 PM EDT Reads: 1,112
DevOps at Cloud Expo, taking place Nov 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 19th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time to wait for long dev...
Sep. 25, 2016 12:15 PM EDT Reads: 3,379
Data is an unusual currency; it is not restricted by the same transactional limitations as money or people. In fact, the more that you leverage your data across multiple business use cases, the more valuable it becomes to the organization. And the same can be said about the organization’s analytics. In his session at 19th Cloud Expo, Bill Schmarzo, CTO for the Big Data Practice at EMC, will introduce a methodology for capturing, enriching and sharing data (and analytics) across the organizati...
Sep. 25, 2016 11:45 AM EDT Reads: 1,646
IoT is fundamentally transforming the auto industry, turning the vehicle into a hub for connected services, including safety, infotainment and usage-based insurance. Auto manufacturers – and businesses across all verticals – have built an entire ecosystem around the Connected Car, creating new customer touch points and revenue streams. In his session at @ThingsExpo, Macario Namie, Head of IoT Strategy at Cisco Jasper, will share real-world examples of how IoT transforms the car from a static p...
Sep. 25, 2016 11:30 AM EDT Reads: 1,513
The many IoT deployments around the world are busy integrating smart devices and sensors into their enterprise IT infrastructures. Yet all of this technology – and there are an amazing number of choices – is of no use without the software to gather, communicate, and analyze the new data flows. Without software, there is no IT. In this power panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists will look at the protocols that communicate data and the emerging data analy...
Sep. 25, 2016 11:00 AM EDT Reads: 1,571
SYS-CON Events announced today that China Unicom will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. China United Network Communications Group Co. Ltd ("China Unicom") was officially established in 2009 on the basis of the merger of former China Netcom and former China Unicom. China Unicom mainly operates a full range of telecommunications services including mobile broadband (GSM, WCDMA, LTE F...
Sep. 25, 2016 10:30 AM EDT Reads: 1,700
The Transparent Cloud-computing Consortium (abbreviation: T-Cloud Consortium) will conduct research activities into changes in the computing model as a result of collaboration between "device" and "cloud" and the creation of new value and markets through organic data processing High speed and high quality networks, and dramatic improvements in computer processing capabilities, have greatly changed the nature of applications and made the storing and processing of data on the network commonplace.
Sep. 25, 2016 10:15 AM EDT Reads: 874
Video experiences should be unique and exciting! But that doesn’t mean you need to patch all the pieces yourself. Users demand rich and engaging experiences and new ways to connect with you. But creating robust video applications at scale can be complicated, time-consuming and expensive. In his session at @ThingsExpo, Zohar Babin, Vice President of Platform, Ecosystem and Community at Kaltura, will discuss how VPaaS enables you to move fast, creating scalable video experiences that reach your...
Sep. 25, 2016 10:00 AM EDT Reads: 936
Big Data has been changing the world. IoT fuels the further transformation recently. How are Big Data and IoT related? In his session at @BigDataExpo, Tony Shan, a renowned visionary and thought leader, will explore the interplay of Big Data and IoT. He will anatomize Big Data and IoT separately in terms of what, which, why, where, when, who, how and how much. He will then analyze the relationship between IoT and Big Data, specifically the drilldown of how the 4Vs of Big Data (Volume, Variety,...
Sep. 25, 2016 10:00 AM EDT Reads: 976
If you’re responsible for an application that depends on the data or functionality of various IoT endpoints – either sensors or devices – your brand reputation depends on the security, reliability, and compliance of its many integrated parts. If your application fails to deliver the expected business results, your customers and partners won't care if that failure stems from the code you developed or from a component that you integrated. What can you do to ensure that the endpoints work as expect...
Sep. 25, 2016 09:00 AM EDT Reads: 1,565
The Internet of Things can drive efficiency for airlines and airports. In their session at @ThingsExpo, Shyam Varan Nath, Principal Architect with GE, and Sudip Majumder, senior director of development at Oracle, will discuss the technical details of the connected airline baggage and related social media solutions. These IoT applications will enhance travelers' journey experience and drive efficiency for the airlines and the airports. The session will include a working demo and a technical d...
Sep. 25, 2016 08:00 AM EDT Reads: 1,686