browser - hard refresh

Web/Browser 2014. 8. 27. 22:27


Your browser saves bandwidth by saving parts of web pages, usually to your hard drive, in a system known as cache. This ensures that identical content is downloaded only once. Sometimes, strange website behavior can make it necessary to bypass this cache, forcing your browser to re-download a web page's complete content.

When you encounter strange behavior, first try bypassing your cache. In most cases you can use the simple instructions shown to the right, or see the complete browser-specific instructions below. If this is not enough, you can try performing a "purge" of Wikipedia's server cache (see instructions below). If problems persist, report them at Wikipedia:Village pump (technical).

In unusual circumstances, it may be worth clearing the entire cache.

Bypassing cache

Internet Explorer

Use one of the following:

  • Hold the Ctrl key and press the F5 key.
  • Hold the Ctrl key and click the "Refresh" button on the toolbar.

Google Chrome

On Windows, use one of the following:

  • Hold the Ctrl key and press the F5 key.
  • Hold the  Shift key and press the F5 key.
  • Hold the  Shift key and click the Reload button on the navigation toolbar.
  • Hold the Ctrl key and click the Reload button on the navigation toolbar.

On Mac OS X:

  • Hold the  Cmd key and press the R key.

On Linux:

  • Hold the Ctrl key and press the F5 key.

Firefox and other related browsers

In FirefoxSeaMonkeyNetscape 6, and others, use one of the following:

  • Hold the Ctrl key and press the F5 key.
  • Hold both the Ctrl and  Shift keys and then press R.
  • Hold the  Shift key and click the Reload button on the navigation toolbar.
  • On a Mac, use the  Cmd key instead of Ctrl.

Safari

For version 4 and newer:

  • Hold down the  Shift key and click the Reload toolbar button.

For version 3 and older:

  • Hold down the  Cmd key and press R. This kind of "regular" reload will usually bypass the cache.

Note that Apple claims that clicking the "Reload" toolbar button has the same effect as  Cmd+R, but this is not true; frequently the button will not bypass the cache.

Opera

Use one of the following:

  • Hold the Ctrl key and press the F5 key.
  • Hold the  Shift key and click the Reload button on the navigation toolbar.
  • Hold the Ctrl key and click the Reload button on the navigation toolbar.
  • Hold the  Shift key and press the F5 key.

Konqueror

  • Press F5 or click the "Reload" button on the toolbar.

Unlike other browsers, Konqueror seems to bypass its cache whenever you reload a page.

Cache clearing and disabling

Internet Explorer

To completely clear the cache in Internet Explorer 9 and later versions:

  1. Click "Tools" (the Gear-shaped button on the top-right section of the browser), point to "Safety" and click "Delete Browsing History…" (keyboard shortcut: Ctrl+ Shift+Del).
  2. Select "Temporary Internet Files" at the top, and click "Delete". (If Wikipedia is in your list of favorites, you may need to turn off the "Preserve Favorites website data" at the top of the dialog box.)
  3. Internet Explorer will now silently delete the items you have chosen. Once finished, the notification bar appears at the bottom of the screen, stating that the selected browsing history has been deleted.

To completely clear the cache in Internet Explorer 8:

  • Click the "Tools" menu then select "Delete Browsing History".

To completely clear the cache in Internet Explorer 7:

  • Click "Tools" and select "Internet Options", choose the "General" tab and click "Delete Files" under the Temporary Internet Files section. If you want, you can also opt to delete cookies and browsing history.

To completely clear the cache in older versions of Internet Explorer:

  • Click on "Tools" and then "Internet Options", and choose the "General" tab. Then click on "Delete…" under "Browsing history". In the "Temporary Internet files" section, click "Delete Files…". You will then get a dialogue box asking if you want to delete just the temporary files, or all off-line content. Choose the latter and click "OK".

To change cache settings (not recommended for most users):

  • Select Tools ‣ Internet Options ‣ Temporary Internet files ‣ Settings… to make advanced configuration changes to the cache.

Google Chrome

To clear the cache:

  1. Go to the "Tools" menu (the three horizontal bars on the upper right of the browser) and click on "History" (Shortcut: Ctrl+H).
  2. Click on "Clear all browsing data…" (Shortcut: Ctrl+ Shift+Del).
  3. Select the types of data you want to clear, include "Empty the cache" option.

If you would like to keep the data in your cache but test Wikipedia without using it, you can use the "incognito" browsing option.

To disable the cache:

  1. Open Developer Tools (F12Ctrl+ Shift+I or Tools ‣ Developer Tools).
  2. Go to Settings by clicking on the cogwheel icon in lower left corner of the Developer Tools window.
  3. Check the "Disable Cache" check-box.

Firefox and other related browsers

To completely clear the cache:

  • In versions of Firefox that display a single, orange "Firefox" button: click the "Firefox" button and click "Options". Select the "Advanced" section, and go to the "Network" tab, and click the "Clear Now" button. Then click "OK".
  • When Firefox displays a menu bar, from the "Edit" or "Tools" menu, choose "Preferences" or "Options". Select the "Advanced" section, and go to the "Network" tab. Click the button called "Clear Now". Then click "OK".
  • In SeaMonkey and later versions of Netscape, choose Edit ‣ Preferences…, expand the "Advanced" section and choose "Cache". Click on the "Clear Cache" button.

To disable caching in Firefox (not recommended for most users):

  1. Choose Tools ‣ Options… (or Edit ‣ Preferences in the Linux version).
  2. Choose "Advanced" at the top.
  3. Choose the "Network" tab.
  4. Change the cache size to 0 (zero).

To disable caching in SeaMonkey (not recommended for most users):

  1. Choose Edit ‣ Preferences…
  2. Expand the "Advanced" item near the left bottom.
  3. Choose "Cache" item.
  4. Change the "Size" value to 0 (zero).

If you would keep your data in your cache and test Wikipedia with an empty cache, you can use Private Browsing mode.

Safari

To completely clear the cache:

  • From the "Safari" menu, choose "Empty Cache…" or hold down the  Opt and  Cmd keys and press E.

Opera

To completely clear the cache:

  • From the "Tools" menu, choose "Preferences". Expand the "Advanced" options and choose "History". Click the "Empty now" button.
  • Alternatively, you can clear the cache, history and cookies: From the "Tools" menu, choose "Delete private data". Click "Details", make sure that "Delete entire cache" is selected, and then choose any other data you want to remove.

To disable the cache permanently (not recommended for most users):

  • From the "Tools" menu, choose "Preferences". Expand the "Advanced" options and choose "History". Click on the dropdown menu for "Disk Cache" and select "Off".

Note: On a Mac the "Tools" menu does not have a "Preferences" option. "Opera → Preferences" is the correct menu item.

Konqueror

To completely clear the cache:

  • From the "Settings" menu, select "Configure Konqueror". Scroll down to select the icon labeled "Cache", and click the button labeled "Clear Cache".

Flock

To completely clear the cache:

  1. Go to the "Tools" menu and click on "Options".
  2. Go to "Privacy" and then click on "Cache".
  3. Click on "Clear Cache Now".

Flock v1.0.8 for Mac instructions:

  1. Go to the "Flock" menu and click on "Preferences".
  2. Go to "Privacy" tab and then, under "Private Data" (bottom field), click on the "Clear Now…" button.
  3. Select the "Cache" checkbox (only, or in combination with other desired options).
  4. Click the "Clear Private Data Now" button.

OmniWeb

To completely clear the cache:

  • From the "OmniWeb" menu, choose "Flush Cache" or hold down the  Opt and  Cmd keys and press U.

Purging Wikipedia's server cache

The Wikimedia servers cache a version of articles. When improperly displayed content is contained in a template or other transcluded page, bypassing your own cache might not be enough. You may need topurge the server cache of old page versions.

The server can be instructed to refresh its cache of a page's contents with the action=purge web address parameter. Add this to the end of the address. For example, to purge this page, visit one of the following:

For pages you think may need to be purged on a regular basis, include {{purge}}, which provides readers with an easily-accessible purge link. Don't put this on article space pages.


See also



source - http://en.wikipedia.org/wiki/Wikipedia:Bypass_your_cache#Instructions_for_various_browsers




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Posted by linuxism
,

linux - sshfs

System/Linux 2014. 8. 25. 13:36


Settupg Up SSHFS on CentOS is fairly easy to do and it enables you to mount partitions using accounts that already on the system.

It’s recommended to use ssh keys when mounting partitions with sshfs, if you have not already done so, follow this tutorial on setting up ssh keys.

Installing SSHFS on CentOS
First you have to have the EPEL repo installed, if you already have it installed, skip this command.

Now we can install sshfs with the following:

yum -y install sshfs

You will see sshfs and the fuse kernel module and libraries downloaded and installed.

Load the fuse kernel module used by sshfs

modprobe fuse

Verify fuse module loaded properly

lsmod | grep fuse

You should see something like

fuse                   56800  0

Make a mount point directory where we’ll access the remote filesystem.

mkdir /sshfsmount

Mount the remote partition (on host puppet.example.motorrobot.net in this example).
This will mount root’s home directory on puppet.example.motorrobot.net on the /sshfsmount folder we created before

sshfs root@puppet.example.motorrobot.net: /sshfsmount

Use the mounted partition like any other mount on your system

ls -aul /sshfsmount

Unmount an SSHFS partition

umount /sshfsmount

Keep a volume mounted with autossh
sshfs -o reconnect,compression=yes,transform_symlinks,ServerAliveInterval=60,ServerAliveCountMax=2,ssh_command=’autossh -M 0′ username@server:/ /sshfsmount”



source - http://centoshowtos.org/storage/sshfs/





 

제  목 : sshfs로 원격 파일시스템을 마운트해서 사용하기
작성자 : 좋은진호(truefeel)
작성일 : 2007.5.19(토)

1. sshfs와 FUSE 개요

얼마전에 'Redhat Enterprise Linux securely mount remote Linux / UNIX directory or file system using SSHFS (http://www.cyberciti.biz/tips/rhel-centos-mounting-remote-filesystem-using-sshfs.html )' 제목의 글을 봤다.
예전에도 sshfs에 대한 글들은 봤으나 사용은 해보지 않다가 scp로 파일 복사를 자주 해야했던 최근 일을 떠올렸다. 좀 더 편하고 나은 방법이 있는데, 굳이 돌아갈 필요가 뭐가 있겠는가. 일상적인 사용을 위해 하나씩 살펴보았다.

ssh를 통해 원격지 파일시스템을 로컬에 마운트하는 sshfs를 사용하기 위해서는 먼저 FUSE가 필요하다.
FUSE(Filesystem in Userspace)은 커널이 아닌 유저공간에서 구현할 수 있는 파일시스템으로 Linux, FreeBSD, Max OSX(MaxFUSE라고 부릅니다.)에서 사용할 수 있다. 이들 OS에서는 FUSE 기반의 다양한 파일시스템을 맛 볼 수 있다.

- 지금 소개하는 sshfs를 비롯하여,
- 리눅스에서 NTFS파일시스템을 사용하기 위한 ntfsmount,
- 리눅스에서 NTFS파일시스템을 읽고 쓸수 있는 Captive NTFS,
  ( Captive NTFS에 대해서는 2003년 11월에 '리눅스에서 NTFS 파일시스템 읽고 쓰기' ( http://coffeenix.net/board_view.php?bd_code=120 )란 제목의 글을 써둔게 있으니 참고하기 바란다. )
- NTFS파일시스템을 읽고 쓰는 또다른 드라이버인 NTFS-3G,
- BitTorrent 의 파일형식인 .torrent 를 파일시스템으로 마운트하는 BitTorrent File System,
- 오픈솔라리스의 ZFS 파일시스템을 리눅스에서 사용하기 위한 ZFS on FUSE, ( 'Google Summer of Code 2006'의 결과물 중 하나 )
- Gmail을 파일시스템처럼 사용하는 GmailFS

등 FUSE로 인해 파일시스템의 확장은 벽이 없어졌다.
FUSE는 현재 리눅서 커널 2.6.14 이상에 공식적으로 포함되어 있지만, 리눅스 2.6.14이상을 쓰지 않아도 된다. 커널에 포함이 안되어 있을 뿐 FUSE 받아서 설치하면 되니깐.

2. FUSE와 sshfs 설치

FUSE와 sshfs 설치는 너무 쉬우니 간단히 설명한다.

http://fuse.sourceforge.net/ 에서 FUSE 소스를 받는다.
리눅스 커널 2.6.9 이상인 경우는 FUSE 2.6.X 버전을 받고, 커널 2.6.9보다 낮고 2.4.21보다 높으면 FUSE 2.5.x 버전을 받으면 된다.

 
./configure
make
make install
 


그리고, /etc/ld.so.conf 에 /usr/local/lib 를 넣고 ldconfig 명령을 내려준다.

sshfs를 설치해보자. sshfs 홈( http://fuse.sourceforge.net/sshfs.html )에서 소스를 받는다.

 
./configure
make
make install
 


3. sshfs로 마운트하기

sshfs 명령 사용은 간단하다. ssh와 scp 명령과 비슷하다. 다음 명령을 보면 접속할 서버명과 마운트할 포인트만 지정해주면 끝난다.

 
sshfs truefeel@coffeenix: /home/truefeel/mount/master/
Password:
 


df명령과 mount 명령으로 확인해보자. 마운트가 정상적으로 됐음을 확인할 수 있으나 용량 표시는 정상적으로 표시되지 않았다.

 
df -h
Filesystem            Size  Used Avail Use% Mounted on
... 생략 ...
sshfs#master:        1000G     0 1000G   0% /home/truefeel/mount/master
mount
... 생략 ...
sshfs#master: on /home/truefeel/mount/master type fuse (rw,nosuid,nodev,large_read,max_read=65536,user=truefeel)
 


sshfs를 할 때 원격지 ssh서버의 UID와 GID가 로컬 사용자가 다를 경우 액세스가 안되는 경우도 있는데, 이 때는 -o allow_other (NFS에서 /etc/exports파일의 all_squash 옵션으로 보면 됨)이나 -o uid=UID, -o gid=GID 옵션으로 해결 할 수 있다.

sshfs 명령 실행중에 발생할 수 있는 2가지 에러에 대해 살펴보자.

1) sshfs: error while loading shared libraries: libfuse.so.2: cannot open shared object file: No such file or directory
   libfuse.so.2 공유 라이브러리를 찾지 못해서 발생한 것이다. '2. FUSE와 sshfs 설치'중에 /etc/ld.so.conf 설정과 ldconfig 명령으로 해결할 수 있다.

2) fusermount: fuse device not found, try 'modprobe fuse' first
   fuse 커널 모듈이 로딩되지 않았다. modprobe fuse 명령을 실행한다.

이제 사용 완료했으면 unmount를 해보자. unmount는 fusermount 명령 또는 umount 명령으로 할 수 있다.

 
fusermount -u /home/truefeel/mount/master/
 


4. 참고 자료

* Redhat Enterprise Linux securely mount remote Linux / UNIX directory or file system using SSHFS
  http://www.cyberciti.biz/tips/rhel-centos-mounting-remote-filesystem-using-sshfs.html
* How to mount a remote ssh filesystem using sshfs
  http://ubuntu.wordpress.com/2005/10/28/how-to-mount-a-remote-ssh-filesystem-using-sshfs/

* Filesystem in Userspace
  http://fuse.sourceforge.net/
* PYRASIS가 보는 Winter of Code 2006
  http://www.pyrasis.com/main/Blog/CodeAndSoftware/2006-12



출처 - http://coffeenix.net/board_view.php?bd_code=1491





Posted by linuxism
,


VirtualBox is a Net Reliant favorite when it comes to virtualization. It is a professional, enterprise grade solution that runs on Windows, Linux, Macintosh, and Solaris hosts.

VirtualBox allows for flexible storage management by allowing for the creation of dynamically allocated guest images. Most users go for the dynamically expanding images in VirtualBox as they do not want to limit themselves to a small virtual disk size and at the same time do not want to waste disk space on their host while the guest doesn't actually need it. Although these images will initially be very small and occupy minimal storage space, over time the images will grow. This is due to the image expanding every time a disk sector (virtual) is written to for the first time.

To help reduce excess disk usage, VirtualBox provides a mechanism for compacting dynamically allocated guest images. Below are the steps to follow if your guest operating system is Linux:

  1. Start the Linux virtual machine;
  2. Clean the free space on the disk of the Linux virtual machine;
  3. Shutdown the Linux virtual machine;
  4. Use the VirtualBox VBoxManage utility to compact the Linux guest image.

Step 1: Start the Linux Virtual Machine

Start the Linux Virtual Machine and log in with administrative rights.

Step 2: Clean any free disk space

The most effective way to clean free disk space on a Linux drive is to use the Linux dd utility which is a bit-stream duplicator. Open up a terminal window and type the following command:

dd if=/dev/zero of=zerofillfile bs=1M

This command will zero-fill any free disk space on the virtual Linux drive.

  • if= specifies the input file;
  • /dev/zero indicates a bit-stream of zeros
  • of= specifies the output file
  • zerofillfile name of the file containing the bit-stream of zeros
  • bs= indicates the block size
  • 1M indicates that the block size will be 1 megabyte

Once the dd has completed, you will see a message in your terminal window indicating that there is no space left on the device:

dd: writing 'zerofillfile': No space left on device

You can now remove zerofillfile using the Linux rm utility:

rm zerofillfile

Step 3: Shutdown the Linux Virtual Machine

 End your session and shutdown the Linux Virtual Machine.

Step 4: Compact the Linux guest image

To compact the Linux guest image, use the VirtualBox VBoxManage utility. Assuming a Windows host, use the following command at the DOS prompt:

VBoxManage modifyhd --compact "[drive]:\[path_to_image_file]\[name_of_image_file].vdi"

Ensure that you replace the items in square brackets with your parameters.

If your Windows host complains that VBoxManage cannot be found or is an invalid command, you may need to explicitly specify the path to the VirtualBox executables. So a complete example for compacting a Linux guest image at the DOS prompt is as follows:

C:\> path C:\Program Files\Oracle\VirtualBox
C:\> VBoxManage modifyhd --compact "C:\netreliant_VMs\linux_001.vdi"

Once the VirtualBox VBoxManage utility is running you will see progress indicators in 10% increments starting from 0% to 100%. And once the process is complete, you should have a smaller disk image file.



source - http://www.netreliant.com/news/8/17/Compacting-VirtualBox-Disk-Images-Linux-Guests.html#.U_oRRnV_sW0






Virtual Machine

# dd if=/dev/zero of=zerofillfile bs=1M

dd: writing `zerofillfile': No space left on device

30776+0 records in

30775+0 records out

32270835712 bytes (32 GB) copied, 834.076 s, 38.7 MB/s


# ll
-rw-r--r--. 1 root  root   31G Jan 14 09:57 zerofillfile

# rm ./zerofillfile 
rm: remove regular file `./zerofillfile'? y


Host Machine
# ll
-rw-------.  1 root root  31G Jan 14 10:11 centOS6.5_64.vdi

# VBoxManage modifyhd --compact centOS6.5_64.vdi 

0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%


# ll

-rw-------.  1 root root  15G Jan 14 10:15 centOS6.5_64.vdi


# VBoxHeadless --startvm "centOS6.5_64" --vrde off &








VirtualBox is a Net Reliant favorite when it comes to virtualization. It is a professional, enterprise grade solution that runs on Windows, Linux, Macintosh, and Solaris hosts.

VirtualBox allows for flexible storage management by allowing for the creation of dynamically allocated guest images. Most users go for the dynamically expanding images in VirtualBox as they do not want to limit themselves to a small virtual disk size and at the same time do not want to waste disk space on their host while the guest doesn't actually need it. Although these images will initially be very small and occupy minimal storage space, over time the images will grow. This is due to the image expanding every time a disk sector (virtual) is written to for the first time.

To help reduce excess disk usage, VirtualBox provides a mechanism for compacting dynamically allocated guest images. Below are the steps to follow if your guest operating system is Windows:

  1. Start the Windows virtual machine and delete any unnecessary files;
  2. Defragment the disk of the Windows virtual machine;
  3. Clean the free space on the disk of the Windows virtual machine;
  4. Shutdown the Windows virtual machine;
  5. Use the VirtualBox VBoxManage utility to compact the Windows guest image.

Step 1: Start the Windows Virtual Machine and Delete Unnecessary Files

Start the Windows Virtual Machine and delete any files that you don't need. Places to start are:

  • Empty the recycle bin;
  • Delete files in your temp folders;
  • Clear any web browser caches;
  • Clear any application caches.

Step 2: Defragment the Disk

  • Locate your hard disk drive using Windows Explorer in the virtual machine;
  • Right-click the drive and choose the Properties option;
  • Then select the Tools tab and click the Defragment now ... button.

Follow the steps to defragment the virtual Windows disk.

Step 3: Clean any free disk space

After the disk has been defragmented, the virtual Windows drive will still have unused space containing garbage bits and bytes. These garbage bits and bytes are from the contents of files that used to occupy that space but that are no longer there.

The most effective way to clean free disk space on a Windows drive is to overwrite the unused space with a bitstream of zeros or to zero-fill any free space.

Windows does not come with a native utility to zero-fill unused space but you can find the excellent SDelete tool at Microsoft's TechNet: http://technet.microsoft.com/en-us/sysinternals/bb897443.aspx

SDelete (or Secure Delete) is a command line utility. So to zero-fill the virtual Windows disk, type the following at the DOS prompt:

C:\> sdelete.exe -z

where -z is the SDelete parameter to zero any free space.

Once SDelete is running you will see a message similar to the following:

SDelete is set for one pass.
Cleaning free space on c:: 12%

Step 4: Shutdown the Windows Virtual Machine

When SDelete has finished running and the free space cleaned or zeroed is 100%, shutdown the Windows virtual machine.

Step 5: Compact the Windows guest image

To compact the Windows guest image, use the VirtualBox VBoxManage utility. Assuming a Windows host, use the following command at the DOS prompt:

VBoxManage modifyhd --compact "[drive]:\[path_to_image_file]\[name_of_image_file].vdi"

Ensure that you replace the items in square brackets with your parameters.

If your Windows host complains that VBoxManage cannot be found or is an invalid command, you may need to explicitly specify the path to the VirtualBox executables. So a complete example for compacting a Windows guest image at the DOS prompt is as follows:

C:\> path C:\Program Files\Oracle\VirtualBox
C:\> VBoxManage modifyhd --compact "C:\netreliant_VMs\windowsXP_001.vdi"

Once the VirtualBox VBoxManage utility is running you will see progress indicators in 10% increments starting from 0% to 100%. And once the process is complete, you should have a smaller disk image file.



source - http://www.netreliant.com/news/9/17/Compacting-VirtualBox-Disk-Images-Windows-Guests.html#.VY5Txa3tlBc

Posted by linuxism
,