Linux essentials:

• It’s free for download but you have to pay a tiny bit to mail order it or buy it from a company. If you’re getting Linux for more than 2-3 PCs, you can also get training and support at a small free, if you choose to have it. Else it’s the Linux community on the Net to your rescue.
• If you want to get comfortable with Linux, you don’t have to let go of windows. Get Linux installed on a seprate partition and you can switch between Windows and Linux. There are some Linux versions that run off CDs too-xandross and Knoppix.
• You don’t have to be a geek to work with Linux. There are Desktop environments that let you work in Linux as you work in Linux as you would in Windows.

Linux hand in decreasing PC prices.

The PCs bundle the operating system. Linux being an open source operating system, means that the code that runs is open for everyone to see, work with, modify and develop their own innovative apps for it. The deal with this experimentation is that you have to share the knowledge you gained and the software you created with the public domain. So the operating system comes to you for free, or if there are some copyrighted application on it, you play up a bit. But this is nothing compared to the fortune people spend on OSs like windows. And a company bundles Linux and applications based on it with a computer, quite a bit of the software cost comes down.

Linux came into being about 11 years ago- it was developed by Linux Tornados of Finland along with a group of programmers from the open source software movement. Linux was mostly something only the geeks worked with. And yes, it was mostly about commands and programming. But over the years with so many Linux enthusiasts (about 50 million of them) working on it and sharing knowledge about it, quite a few versions have come up which are as easy to use as windows. And developers are still free to work with code and enhance it.

Linux is growing steadily year after year. With a passionate community backing it, with big companies Like IBM and HP pledging their support for it, it’s no wonder Linux- the wonder operating system for servers of the past, has also made it to the desktops of today. Not in a sweeping way yet, but in ways that will help you –the user. PC prices are already on their way down. And you get more choice with operating systems and applications. From being an OS only computer professionals had heard about, Linux, in a short time, has made a transition into the lucrative and high profile home PC segment. Most of the decision to switchover sounds very economical. From a measly base of a few thousand users, Linux now boasts of close to 50 million users, cracking the monolith of Microsoft’s monopoly. Companies like IBM, HP and Dell have also taken to Linux in a big way. Microsoft doesn’t agree with the free concept at all-the software is free but the support isn’t Windows code to outsiders so they could build on to it. Very recently though, the company has allowed part of the code to be opened up to some US government are vying with each other to get tech-savvy and help the citizens through e-governance, the opening up of the OS code is important, countries like India need a variety of regional language fonts and content to be created which can’t done without Microsoft’s help, if the choice is Windows. Since this isn’t happening much, they have gone ahead with adopting Linux.

Linux is based on the commercial OS, UNIX. All the OSs tries to pack in command line management of systems. System administrators of companies use command lines all the times as their lifeline, but it’s not really meant for regulars users. But UNIX and Linux are not all about just command line stuff. UNIX has had a graphical user interface for 30 years. In its 11 years Linux has always had always had a GUI too-in fact a choice of GUIs.

Linux Versions:

If there are so many people working on it. There’s likely to be many Linux versions too. Many companies working on Linux have come up with what are called Linux distributions. There are Linux versions that are compiled and packaged and released with various additional software.

The popular distributions or destroys include Red Hat Linux Mandrake Linux, Corel Linux SUSE Linux and Debian . it’s just like having different flavors of ice cream. True to the spirit of open source, if you download the distro from the company’s Website, it is free for use. But the distros are usally quite huge. If you are getting the distorts from the company, be ready to pay up a tiny bit. Companies compile the packages, make installation hassle free, bundle applications, add a manual, and extend any support you need. So they charge a fee for all this.

One note here though: the free in Linux stands for freedom of choice, to redistribute, to install a feature, freedom to modify the source code. That’s the spirit of Linux being free.

Linux better than other OS

Linux users won’t even bat an eyelid before they say an emphasis comes from a deep dislike of Microsoft’s practice of changing the earth for software. But a lot of it comes from the fact they are ready to swear upon-that Linux is more stable. There are no blue screens and no viruses to speak of. Linux has a better security support for multi-users, lets you set up a stable server, internet gateways etc, and still lets it-self to be used as a desktop workstation. Add to that it being free, and they argue that you don’t lose anything by giving it a try. You get free support on the Net quickly on any query you may have. And you don’t even have to wipe out your Windows. Just get Linux on a different hard disk partition and free to switch between the OSs as you please .

Myths about Linux

Installation:

Linux is hard to install, isn’t it? Not really. Most people haven’t ever installed Windows on their computers either-since it comes preloaded. Linux is as easy-some say easier-to install compared to Windows. You can install it through a graphical user interface like Windows. But what really stumps most people in installing Linux on a second partition on their hard disk, when they want to be able to use both operating systems.

A partition is a way of organizing space on your hard disk by creating virtual sections that are separate from each other. Most computers that are running Windows or MS DOS have one large chunk of space holding the OS. This space is the C drive. If you have a large hard disk, it’s likely that it has been divided up into smaller bits called partitions to help you organize your data better. These partitions are usually called D:\, E:\ etc. you could have Linux on any of these.

Windows 98 creates a file system called FAT32 on the entire hard disk, DOS and Win95 use FAT16. Linux has many file systems-on the most popular is ext3. But you could have Linux installed on Fat32 partitions also.

Linux is geeky and based on text command

Linux has come a long way from being the system of geeks. It has an extremely advanced X Windows systems that has a complete graphical user interface-you know, like Windows. It also has a large number of window manager that let you work with different levels of customization of your desktop.

Linux has a robust character-cell interface where commands need to be typed in. x Windows is a free program that runs with Linux to provide a GUI where the mouse and keyboard can be used extensively. But the X system itself is quite primitive and needs a window manager, or a desktop environment- like GNOME or KDE- to be really usable. Window managers are programs that let you interact with the underlying X system and LinuxOS by relaying commands. The popular window managers are Sawfish, Enlightenment, Black box, after step and Window maker.

As for desktop managers, they have their own window manager and other tools that make you feel that you are working in Window! GNOME and KDE are the most popular of these. GNOME stands for GNU Network Model Environment and KDE for K desktop Environment. They have tools that allow drag and drop, have panels and taskbar- almost like clones of windows.

Hardware compatibility problem and few applications that run on Linux

Well, most new distributions will detect and configure your hardware in a jiffy, unless you have some really old or exotic piece of hardware. Only Win modems (internal modems driven by Window drivers) face problems.

As for software, there’s plenty. And most of it comes free-free for you to use, modify and configure according to your needs. Other packages are commercial and you have to buy the software-but this is mostly for the software and training you need, and not for the support and training you need, and not for the software itself. Sometimes, if you have the Windows version (as a doom) you can download a small program that will allow you to play the game in Linux. Here what’s available?

Office suites: Star Office, Open Office, Applixware, Corel WordPerfect

Graphics: GIMP, Corel Photo paint

Music: XMMS, Free amp, Real Player

Video: MTV, Xine

Games: FreeCiv, Tux racer, Doom, Quake, Heretic, Unreal

And the list is growing.

Linux varieties:

• Debian : One of the oldest and still most popular distros is Debian. This Project is a voluntary effort of a team of programmers who developed the GNU system. Debian is not very easy to install, and that has been its problem, Debian also has its own software comes with a. DEB extension. Updating and installing new software is very easy. The applications bundled with Debian are great for even a power user.
• RedHat: Probably the most popular and in many ways the leading distro. It’s currently in version 8. The installation and configuration is easy. A blue curve file manager and the default GNOME desktop make it look simply stunning. It comes with a host of tools that allow usage as a server and as a workstation. The Red Hat Package Manger(RPM) format developed by Red Hat has almost become the defector for software distribution in Linux world. Installing new software is a breeze. It also has an advanced and easy font management system that makes fonts in X Windows look cool. But being the leader comes at a price. Red Hat charges a little more than others for its istro.
• Mandrake: Mandrake Linux is now in its 9 version. This distro can be installed on a native Windows Partition using the Lin4Win tool, but this may slow the machine down. It also lets you do a traditional Linux install into its own dedicated partition. Mandrake’s configuration and software installation is painless. It follows a slightly modified RPM architecture called mdk.rpm but most Red Hat software can also be used for Mandrake. The outstanding feature in this distro is the collection of window managers-eye-candy freaks will have a great time.
• SUSE : From Germany comes the Chameleon Distro, SUSE. Now in its 8.1 avatar, it has one of the most extensive software packages compiled, and getting them installed is easy with yast (Yet another Software Tool) which gives a centralized interface from where you can pick and choose the software to be installed. Among other things, SUSE comes with some stunning 3D games that showcase Linux’s gamming prowess.
• Corel/Xandross : Corel entered the Linux distro market with Corel Linux a few years ago. Now it has merged into Xandross OS, which is based on Corel Linux. This is a Debian-type distro, and can be installed without much fuss after resizing the Windows partition. Xandross contains Crossover office, which is a refined retail version of WINE that lets you install and run many Microsoft apps.

Windows applications in Linux

Some applications have been ported over to Linux, other run with a program called WINE (Wine is Not an Emulator). Crossover, commercially available software also lets you use your Windows programs Linux. VMWare is another program that lets you run Windows under Linux.

Bottom Line:

The cool thing about Linux is that most software is free, and you can legitimately use them without worrying about piracy. If you’re worried that Linux won‘t look as pretty as windows can, all you have to do is check out some of the cool Linux interfaces and Window managers. But you don’t find a lot of multimedia titles for Linux. And if you’re into a lot of these, Windows in the way to go. So if you have a PC that runs both, you can easily switch between the two, and get the best of both worlds.

Introduction to Linux:

It’s a free operating system available to download but you have to pay a tiny bit to mail order it or buy it from a company. Linux came into being about 11 years ago- it was developed by Linux Tornados of Finland along with a group of programmers from the open source software movement.

Linux is growing steadily year after year. With a passionate community backing it, with big companies Like IBM and HP pledging their support for it, it’s no wonder Linux- the wonder operating system for servers of the past, has also made it to the desktops of today.

Linux is based on the commercial OS, UNIX. All the operating systems try to pack in command line management of systems. System administrators of companies use command lines all the times as their lifeline, but it’s not really meant for regulars users.

Tips for Home Users:

If you want to get comfortable with Linux, you don’t have to let go of windows. Get Linux installed on a separate partition and you can switch between Windows and Linux. For new users who don’t have any computer background learning windows or Linux both takes same time and sitting.
It is suggested that new PC buyers should get both operating systems installed and should use them equally. If you’re getting Linux for more than 2-3 PCs, you can also get training and support at a small free, if you choose to have it. Else it’s the Linux community on the Net to your rescue.
You don’t have to be a great computer user to work with Linux. There are Desktop environments that let you work in Linux as you work in Windows. As you work with windows, same is the case with Linux.
Linux hands in decreasing PC prices.

PC prices are already on their way down. And you get more choice with operating systems and applications. From being an OS only computer professionals had heard about, Linux, in a short time, has made a transition into the lucrative and high profile home PC segment.

The PCs bundle the operating system. Linux being a free open source operating system means that the code that runs is open for everyone to see, work with, modify and develop their own innovative applications for it. But this is nothing compared to the money people spend on Operating Systems like windows. And a company bundles Linux and applications based on it with a computer, quite a bit of the PC cost comes down. Presently some branded PC’s coming with Linux are available for Rs: 25000/- onwards.

Linux is better than other OS

Linux users won’t even bat an eyelid before they say an emphasis comes from a deep dislike of Microsoft’s practice of changing the earth for software. But a lot of it comes from the fact they are ready to swear upon-that Linux is more stable. According to a latest survey Web Hosts are using Linux Based Servers for hosting purposes.

One note here though: the free in Linux stands for freedom of choice, to redistribute, to install a feature, freedom to modify the source code. That’s the spirit of Linux being free.

Security:

Linux has a better security support for multi-users, lets you set up a stable server, internet gateways etc, and still lets it-self to be used as a desktop workstation. There are no blue screens and no viruses to speak of. It is rarely attacked by any viruses and there are very less number of viruses written for Linux. It can be given 10+ points on a 10 point scale for security.

Myths about Linux

Installation:

Linux is hard to install, isn’t it? Not really. Most people haven’t ever installed Windows on their computers either-since it comes preloaded. Linux is as easy-some say easier-to install compared to Windows. You can install it through a graphical user interface like Windows. These days Linux Versions are easier to install than Windows. But what really stumps most people in installing Linux on a second partition on their hard disk, when they want to be able to use both operating systems.

A partition is a way of organizing space on your hard disk by creating virtual sections that are separate from each other. Most computers that are running Windows or MS DOS have one large chunk of space holding the OS. This space is the C drive. If you have a large hard disk, it’s likely that it has been divided up into smaller bits called partitions to help you organize your data better. These partitions are usually called D:\, E:\ etc. you could have Linux on any of these.

Windows 98 creates a file system called FAT32 on the entire hard disk, DOS and Win95 use FAT16. Linux has many file systems-on the most popular is ext3. But you could have Linux installed on Fat32 partitions also.

Linux is very difficult and based on text command

Linux has come a long way from being the system of brilliant computer users. It has extremely advanced X Windows systems that have a complete graphical user interface-you know, like Windows. It also has a large number of window manager that let you work with different levels of customization of your desktop.

Linux has a robust character-cell interface where commands need to be typed in. x Windows is a free program that runs with Linux to provide a GUI where the mouse and keyboard can be used extensively. But the X system itself is quite primitive and needs a window manager, or a desktop environment- like GNOME or KDE- to be really usable. Window managers are programs that let you interact with the underlying X system and Linux OS by relaying commands. The popular window managers are Sawfish, Enlightenment, Black box, after step and Window maker.

As for desktop managers, they have their own window manager and other tools that make you feel that you are working in Window! GNOME and KDE are the most popular of these. GNOME stands for GNU Network Model Environment and KDE for K desktop Environment. They have tools that allow drag and drop, have panels and taskbar- almost like clones of windows.

Hardware compatibility problem and few applications that run on Linux

Well, most new distributions will detect and configure your hardware in a jiffy, unless you have some really old or exotic piece of hardware. All hardware are properly detected and their drivers installed. Only Win modems (internal modems driven by Window drivers) face problems.

As for software, there’s plenty. And most of it comes free-free for you to use, modify and configure according to your needs. Almost all excellent software for Linux is free and you don’t lose anything by giving it a try. You get free support on the Net quickly on any query you may have. And you don’t even have to wipe out your Windows. Just get Linux on a different hard disk partition and free to switch between them as you please.

Other packages are commercial and you have to buy the software-but this is mostly for the software and training you need, and not for the software itself. Sometimes, if you have the Windows version (as a doom) you can download a small program that will allow you to play the game in Linux. The games in Linux are of very high quality and features. You’ll enjoy them. Here what’s available?

Office suites: Star Office, Open Office, Applixware, Corel WordPerfect

Graphics: GIMP, Corel Photo paint

Music: XMMS, Free amp, Real Player

Video: MTV, Xine

Games: FreeCiv, Tux racer, Doom, Quake, Heretic, Unreal And the list is growing.

Linux varieties for Home Users:

If there are so many people working on it. There’s likely to be many Linux versions too. Many companies working on Linux have come up with what are called Linux distributions. There are Linux versions that are compiled and packaged and released with additional software.

RedHat: Probably the most popular and in many ways the leading version. It’s currently in version 9. The installation and configuration is easy. A blue curve file manager and the default GNOME desktop make it look simply stunning. It comes with a host of tools that allow usage as a server and as a workstation. The Red Hat Package Manger(RPM) format developed by Red Hat has almost become the defector for software distribution in Linux world. Installing new software is a breeze. It also has an advanced and easy font management system that makes fonts in X Windows look cool.

Mandrake: Mandrake Linux is now in its 10 version. It can be installed on a native Windows Partition using the Lin4Win tool, but this may slow the machine down. It also lets you do a traditional Linux install into its own dedicated partition. Mandrake’s configuration and software installation is painless. It follows a slightly modified RPM architecture called mdk.rpm but most Red Hat software can also be used for Mandrake. The outstanding feature in this version is the collection of window managers-eye-candy freaks will have a great time.

SUSE: From Germany comes the Chameleon, SUSE. Now in its 8.x avatar, it has one of the most extensive software packages compiled, and getting them installed is easy with yast (Yet another Software Tool) which gives a centralized interface from where you can pick and choose the software to be installed. Among other things, SUSE comes with some stunning 3D games that showcase Linux gamming prowess

Corel/Xandross: Corel entered the Linux market with Corel Linux a few years ago. Now it has merged into Xandross OS, which is based on Corel Linux. This is a Debian-type version, and can be installed without much fuss after resizing the Windows partition. Xandross contains Crossover office, which is a refined retail version of WINE that lets you install and run many Microsoft apps.

Windows applications in Linux

Some applications have been ported over to Linux, other run with a program called WINE (Wine is Not an Emulator). Crossover, commercially available software also lets you use your Windows programs on Linux. VMWare is another program that lets you run Windows under Linux. Now many software companies have started developing high end software for Linux.

Bottom Line:
The cool thing about Linux is that most software is free, and you can legitimately use them without worrying about piracy. If you’re worried that Linux won‘t look as pretty as windows can, all you have to do is check out some of the cool Linux interfaces and Window managers. But you don’t find a lot of multimedia titles for Linux. And if you’re into a lot of these, Windows is in the way to go. So if you have a PC that runs both, you can easily switch between the two, and get the best of both worlds. runescape goldrunescape goldrunescape goldrunescape goldrs goldrs goldrs goldpowerlevelingpowerlevelingpowerlevelingpowerlevelingpowerlevelingpower levelingpower levelingpower levelingpower levelingpower levelingwow account wow accountsnike shoesjordan shoesOil painting

This article summarises many of the commonly used control sequences that are used in all Linux terminals.

CTRL-C

This is the most commonly used sequence. In the bash shell, CTRL-C will terminate any currently running process and return you to the bash prompt. For example, if you accidentally run a command that does not stop, use CTRL-C to cancel the command.

CTRL-D

Many Unix commands read their input directly from the keyboard. An example is the WC command. WC counts the number of lines, words and characters that a user types in from the keyboard. So if you tpye WC at the command prompt, the command will wait for your input till you use CTRL-D to signal the end of transmission.

CTRL-Z

CTRL-Z means to suspend a program. For example, you are working with a command and you want to stop it temporary as it is taking too long. To do that, you can use CTRL-Z. You can later restore back the command using the fg command.

CTRL-U

If you have messed up a certain command and you want to start all over, instead of using backspace, you can use CTRL-U. CTRL-U resets the current line.

CTRL-H

Instead of using the backspace key, you can use CTRL-H to function the same way. Unless the backspace key is malfunctioned or mapped wrongly, this sequence serves very little purpose.

CTRL-L

If your screen is too cluttered with unwanted information, you can clear the screen using CTRL-L.

CTRL-S

Freeze your screen. This is a good command to use if you decide to go for a coffee break and do not want any process to run till you are back.

CTRL-Q

This sequence is exactly the opposite to CTRL-S. If you have freezed the screen before, you use this command to unfreeze it.

CTRL-J

Functions the same way as the RETURN key.

CTRL-G

Makes a terminal beep sound for fun and entertainment.

Control Sequences are important to all Linux / Unix users. Some sequences are important while some are useless today. It is worth memorising the first few sequences as described in this article.wow goldwow goldwow goldwow goldwow goldWorld Of Warcraft powerlevelingWorld Of Warcraft powerlevelingWorld Of Warcraft powerlevelingWorld Of Warcraft powerlevelingWorld Of Warcraft powerlevelingWorld Of Warcraft powerlevelingWorld Of Warcraft powerlevelingworld of warcraft power leveling

Since being an open-source operating system, Linux hosting tends to be cheaper than Windows hosting. Besides, Linux hosting is considered as one of the main pillars of the LAMP server-software combination - Linux, Apache, MySQL and Php/Perl/Python. Popularity of Linux hosting among web developers can be judged from the fact that a great many open-source software have been created and are being continuously created for free use among discerning web enthusiasts. Whether one chooses Linux hosting or Windows hosting will to a great extent depend on what the webmaster proposes to do with his website. Here is a quick rundown of both Linux hosting and Windows hosting.

Linux Hosting

Linux hosting is a good choice if you consider that you have perpetual options of using open-source software for your hosting needs. Linux hosting would mean that the operating system is fully compatible with PHP, which is steadily becoming the most popular programming language.

It is important to remember that Linux is a breeding ground of practicing programmers all over the globe and innumerable applications are being authored, re-written and tested all the time. What this means in simple terms is Linux hosting will always keep the door open to let in fresh air of new discoveries. For an avid user, nothing beats Linux hosting in this aspect.

The other advantage with Linux hosting is that it is cheap. Why? Since most application software are free to install and use, the hosting cost is reduced to only maintenance of servers. Since proprietary software are not installed, many overhead expenses are avoided in case of Linux hosting. This enables hosting providers to pass on the cost-advantage to its customers of Linux hosting.

Here are some examples of popular open-source application software, mostly in PHP, that can be easily used in Linux hosting.

Ecommerce Shopping Cart : OS Commerce, Zen-Cart
Content Management System : Drupal, PHP-Nuke, Mambo
Blog : Wordpress, Nucleus CMS
Photo Gallery : 4Images, Coppermine

Windows Hosting

Windows hosting makes use of Microsoft’s proprietary Windows software for the host server. In contrast with Linux hosting, Windows hosting allows integration primarily with Microsoft’s own products and services. For example, if you plan dynamic web content, you have to use ASP (Active Server Pages) or the advanced ASP.NET as your programming language, both created by Microsoft to be linked to SQL databases.

Interestingly, if you choose MySQL as your database, you may opt for either Linux hosting or Windows hosting, but in case your choice for database is MS Access, your option is only Windows hosting.

Windows hosting has limited support for CGI / Perl, so if your favorite scripts are in Perl, it has to be Linux hosting for you. On the other hand, good news for FrontPage users is that though it is essentially a proprietary Microsoft-owned software application, many Linux hosting do support FrontPage extensions.

There is an argument that the user interface for Windows hosting is much simpler between the two. However, of late Linux hosting too has improved on this score.

Coming to cost analysis, Windows hosting is costly not only because of proprietary software, but also due to the fact that Windows servers as such are costly, compared to servers used for Linux hosting.

Summing Up

Glossing over, what emerges is that it is the purpose of your website and its future plan that are the determining factors between choosing Linux hosting and Windows hosting. To be sure, all serious hosting providers will, in varying combination, offer a choice of both Windows hosting and Linux hosting.

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Internet based NTP time server systems fall into two categories: primary and secondary reference servers. Primary reference servers utilise a highly accurate external timing reference, such as GPS or radio clocks, to provide precise time. Secondart reference servers synchronise their time with primary reference servers and therefore offer slightly reduced accuracy. Primary reference time servers are stratum one servers, while secondary servers have a stratum greater than one.

The NTP source code is freely downloadable under the GNU public license from the NTP web site at ‘ntp.org’. NTP was originally developed for the LINUX operating system, however, a port to Windows NT is also available. Once the source code has been obtained, it should be installed, compiled and configured on the host computer. This process is automated with the installation and configuration scripts supplied in the distribution. Many Linux based operating systems have the NTP package pre-installed. However, it may be wise to download the most recent version, which is currently 4.2.4.

The NTP daemon is configured via a configuration file ‘ntp.conf’. This configuration file may contain a list of public NTP server references that can be used by the host to synchronise time. The ’server’ command can be used to specify public NTP time references, characters specified after the # symbol are comments:

server time-a.nist.gov # Public NTP server: NIST, Gaithersburg, Maryland server time-c.timefreq.bldrdoc.gov # Public NTP Server: NIST, Boulder, Colorado

When the configuration file is complete the NTP daemon can be started using the ‘ntpd start’ script. Other scripts are vailable that can be used to control the daemon: ‘ntpd stop’, ‘ntpd restart’. There is also a query script available that shows the current synchronisation status of the daemon: ‘ntpq -p’.

The ‘restrict’ command can be used to control access premissions to the NTP server. There are a number of permutations or the ‘restrict’ command; a few examples are listed below.

restrict default ignore #Restrict all access to the time server restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap # Only allow local computers access

Multiple commands can be specified to restrict or disallow access to a range of computers.

NTP provides an additional level of security by utilising authentication codes. This is a mechanism where matching key codes can be specified on a client and server which are encrypted and passed between the server and client. This allows a client to confirm the source of a time message. Authentication keys are configured in the ‘ntp.keys’ file. They are specified using a key reference, encryption code and authentication key. Additionally, trusted authentication keys can be specified using the ‘trusted key’ command is the ‘ntpd.conf’ configuration file.特价机票特价机票机票国际机票国际机票国际机票云南旅游四川旅游拓展训练摄影相册翻译公司翻译公司翻译公司翻译公司管理咨询传奇私服视频会议律师事务所糖尿病货架货架保洁 门禁 门禁衬衫T恤衬衣男士衬衫google优化google左侧排名google排名google排名google排名google优化google优化google左侧排名google左侧排名