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How to Turn Off Lens Search in Google Chrome

Google Chrome makes it easy to disable the Lens search feature and bring back the traditional “Search Google for This Image” context menu option. Here’s how you can do that in Chrome on desktop and Android.

Chrome’s Lens search feature is extremely useful as you can use it to find more information about your selected image. However, if you’d prefer the old reverse search method, it’s easy to disable this new feature and get that old option back. You can always re-enable the Lens search option if you want.

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How to Zip and Unzip Files With Gzip on Linux

There are many file compression utilities, but the one you’re guaranteed to find on every Linux distribution is gzip. If you only learn to use one compression tool, it should be gzip .

Algorithms and Trees

The gzip data compression tool was written in the early 1990s, and it’s still found in every Linux distribution. There are other compression tools available, but no matter which Linux computer you find yourself needing to work on, you’ll find gzip on it. So if you know how to use gzip, you’re good to go without the need to install anything.

gzip is an implementation of the DEFLATE algorithm which was invented—and patented—by Phil Katz of PKZIP fame. The DEFLATE algorithm improved on earlier compression algorithms which all operated on variations of a theme. The data to be compressed is scanned, and unique strings are identified and added to a binary tree.

The unique strings are allocated a unique ID token by virtue of their position in the tree. The tokens are used to replace the strings in the data and, because the tokens are smaller than the data they replaced, the file is compressed. Substituting the tokens for the original strings re-inflates the data back to its uncompressed state.

The DEFLATE algorithm added the twist that the most frequently encountered strings were allocated the smallest tokens and the least frequently encountered strings were allocated larger ones. The DEFLATE algorithm also incorporated ideas from two earlier compression methods, Huffman coding and LZ77 compression.

At the time of writing, the DEFLATE algorithm is nearly three decades old. Three decades ago data storage costs were high and transmission speeds were slow. Data compression was vitally important.

4 Ways to Free Up Disk Space on Linux

Data storage is much cheaper today, and transmission speeds are orders of magnitude faster. But we have so much more data to store, and the world over people are accessing cloud storage and streaming services. Data compression is still vitally important, even if all you’re doing is shrinking something that you need to upload or transmit, or you’re trying to claw back some space on a local hard drive.

The gzip Command

The bigger a file is, the better the compression can be. This is because of two reasons. One is there will be many repeated, identical sequences of bytes throughout a large file. The second reason is the list of strings and tokens needs to be stored in the compressed file so that decompression can take place. With a very small file that overhead can wipe out the benefits of the compression. But even with a fairly small file, there’s likely to be some reduction in size.

Compressing a File

To compress a file, all you need to do is pass the name of the file to the gzip command. We’ll check the original size of the file, compress it, and then check the size of the compressed file.

ls -lh calc-sheet.ods
gzip calc-sheet.ods
ls -lh cal-*

Compressing a spreadsheet

The original file, a spreadsheet called “calc-sheet.ods” is 11 KB,  and the compressed file—also known as an archive file—is 9.3 KB. Note that the name of the archive file is the name of the original file with “.gz” appended to it.

The first use of the ls command targets a specific file, the spreadsheet. The second use of ls looks for all files beginning with “calc-” but it only finds the compressed file. That’s because, by default, gzip creates the archive file and deletes the original file.

That’s not an issue. If you need the original file you can retrieve it from the archive file. But if you prefer to retain the original file, you can use the -k (keep) option.

gzip -k calc-sheet.ods
ls -lh calc-sheet.*

Compressing a file and retaining the original file

This time the original ODS file is retained.

Decompressing a File

To decompress a GZ archive file, use the -d (decompress) option. This will extract the compressed file from the archive and decompress it so that it is indistinguishable from the original file.

ls calc-sheet.*
gzip -d calc-sheet.ods.gz
ls calc-sheet.*

Decompressing a file with gzip

This time, we can see that gzip has deleted the archive file after extracting the original file. To retain the archive file, we need to use the -k (keep) option again, as well as the -d (decompress) option.

ls calc-sheet.*
gzip -d calc-sheet.ods.gz
ls calc-sheet.*

Decompressing a file and retaining the archive file

This time, gzip doesn’t delete the archive file.

Decompressing and Overwriting

If you try to extract a file in a directory where the original file—or a different file with the same—exists,  gzip  will prompt you to choose to abandon the extraction or to overwrite the existing file.

gzip -d text-file.txt.gz

Overwrite prompt from gzip when the file in the archive already file exists in the directory

If you know in advance that you’re happy to have the file in the directory overwritten by the file from the archive, use the -f (force) option.

gzip -df text-file.txt.gz

Forcing overwriting of an existing file

The file is overwritten and you’re silently returned to the command line.

Compressing Directory Trees

The -r (recursive) option causes gzip to compress the files in an entire directory tree. But the result might not be what you expect.

Here’s the directory tree we’re going to use in this example. The directories each contain a text file.

tree level1

Test directory tree structure

Let’s use gzip on the directory tree and see what happens.

gzip -r level1/
tree level1

Directory structure after running gzip on it

The result is gzip has created an archive file for each text file in the directory structure. It didn’t create an archive of the entire directory tree. In fact, gzip can only put a single file in an archive.

We can create an archive file that contains a directory tree and all of its files, but we need to bring another command into play. The tar program is used to create archives of many files, but it doesn’t have its own compression routines. But by using the appropriate options with tar, we can cause tar to push the archive file through gzip. That way we get a compressed archive file and a multi-file or multi-directory archive.

tar -czvf level1.tar.gz level1

The tar options are:

  • c: Create an archive.
  • z: Push the files through gzip.
  • v: Verbose mode. Print in the terminal window what tar is up to.
  • f level1.tar.gz: Filename to use for the archive file.

Output from tar working its way through the directory tree

This archives the directory tree structure and all files within the directory tree.

Getting Information About Archives

The -l (list) option provides some information about an archive file. It shows you the compressed and uncompressed sizes of the file in the archive, the compression ratio, and the name of the file.

gzip -l leve1.tar.gz
gzip -l text-file.txt.gz

Using the -l list option to see compression statistics for an archive

You can check the integrity of an archive file with the -t (test) option.

gzip -t level1.tar.gz

Testing an archive with the -t option

If all is well, you’re silently returned to the command line. No news is good news.

If the archive is corrupt or not an archive you’re told about it.

gzip -t not-an-archive.gz

Using the -t option to test a file that isn't an archive

Speed Versus Compression

You can choose to prioritize the speed of creation of the archive or the degree of compression. You do this by providing a number as an option, from -1 through top -9. The -1 option gives the fastest speed at the sacrifice of compression and -9 gives the highest compression at the sacrifice of speed.

Unless you provide one of these options, gzip uses -6.

gzip -1 calc-sheet.ods
ls -lh calc-sheet.ods.gz
gzip -9 calc-sheet.ods
ls -lh calc-sheet.ods.gz
gzip -6 calc-sheet.ods
ls -lh calc-sheet.ods.gz

Using gzip with different priorities for speed and compression

With a file as small as this, we didn’t see any significant difference in speed of execution, but there was a small difference in compression.

Interestingly, there is no difference between using level 9 compression and level 6 compression. You can only wring so much compression out of any given file and in this case, that limit was reached with level 6 compression. Cranking it up to 9 brought no further reduction in filesize. With bigger files, the difference between level 6 and level 9 would be more pronounced.

Compressed, Not Protected

Don’t mistake compression for encryption or any form of protection. Compressing a file doesn’t give it any security or enhanced privacy. Anyone with access to your file can use gzip to decompress it.

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How to Escape Internet Censorship

As you probably know, the internet isn’t free everywhere: in some countries, people are met with blocks when accessing sites the government doesn’t approve of. Thankfully, there are ways around these blocks, and you don’t even have to be particularly tech-savvy to use them.

Warning: We probably don’t need to tell you this, but if you’re in a country that limits freedom of expression enough to restrict the internet, you need to be very careful when circumventing any blocks. There could be electronic countermeasures in place or even physical ones. As has happened in Myanmar and Russia, police could stop you on the street to check your smartphone. Please, be careful and keep safe.

  • How Blocks Work

To block our site, you would somehow need to cut off access from your ISP to our IP address. That’s how Chinese censorship works: It simply blocks traffic to any IP addresses that have been flagged. These flags can be for any number of reasons, some are because sites have content considered subversive by the authorities, while others offer gambling or pornography.

The nature of the block also reveals how we can get around it: if your government (or even just your ISP) is blocking an IP address, all you need to do is to connect to another, non-blocked IP address and have it connect to the blocked IP address for you, forwarding the traffic through the unblocked IP address for any other sites you want to visit. There are several ways to do so, and we’ll go over a few options below.

  • Proxies: Not Recommended

If diverting your connection in the way we described above sounds like something you’ve heard before, you’re probably already familiar with proxies. These little apps—usually simply accessed through a website—will reroute your connection through an IP address so as to make you appear in that location rather than your own.

Proxies are great for passing a regional block on YouTube or something similarly innocuous. However, for something a little more serious like passing a censorship block, using a proxy is a very bad idea indeed. The connection usually isn’t secured in any way and you can very easily be tracked—claims from proxy providers notwithstanding. Whatever you do, don’t use a proxy to get past blocks.

  • Shadowsocks

There is, however, one exception to the “no-proxies” rule, namely a protocol called Shadowsocks. Though it also doesn’t protect the connection the same as other proxies, it’s less easy to detect than one thanks to it disguising itself. Where a regular proxy can easily be detected by most blocks, Shadowsocks is a HTTPS connection, thus tricking the detection system.

Shadowsocks was developed by a Chinese programmer and it’s widely used there to get past the Great Firewall. There’s no question it works. However, if you’re having any trouble with it or you’re worried about active searches for proxy traffic, you may want to escalate your block-busting by using a VPN.

  • Virtual Private Networks

Virtual private networks are powerful, though slightly overhyped security tools that can help you evade censorship blocks and remain safe while doing so—on paper, at least. VPNs not only reroute your connection, they’ll also encrypt it through a so-called VPN tunnel, which prevents anybody from seeing what you’re doing.

We have a full article on how VPNs work if you’re interested.

For most people, most of the time, VPNs are the best way to get around censorship blocks, but they come with some downsides. The biggest is probably that they cost money, even the cheapest ones out there will set you back $5 to $10 per month, which is more than some people can afford.

The other issue is that you can’t always be sure whether the VPN you have is a good one: the marketing madness surrounding them rises in pitch every few months, it seems. We’ve made a selection of the best VPNs that we feel offer the best value; Mullvad is probably the best choice if you need a cost-effective solution that gets past any censorship blocks, while VyprVPN claims to have a special protocol that can go unnoticed by authorities.

  • ExpressVPN
  • SurfShark
  • Windscribe
  • ProtonVPN
Hide.me
  • ExpressVPN
  • Private Internet Access
  • NordVPN
  • CyberGhost
Best VPN for China
  • VyprVPN
  • Mullvad VPN

As we alluded to above, VPNs aren’t bulletproof—for one, police could simply check your phone for VPN software—as well as being possibly too expensive. One method of bypassing censorship that is harder to detect, as well as being free, is to create an SSH tunnel to a trusted server outside of your country and access the internet through that.

The downside is that you need some tech-savviness to set up an SSH tunnel. We have a full guide on how to use SSH tunneling that will get you on your way, though. If you have the equipment and knowledge necessary, this may be the best option yet.

Other Methods

Besides the methods above, there are other ways to get around blocks, but these usually require some more specialized technical knowledge or some extra setup, as is the case with changing your DNS server or using Tor. Decentralized VPNs are another promising technology. However, as these services are still in their infancy, we wouldn’t quite risk using them yet.

How to Browse Anonymously With Tor

However, to repeat our earlier point, there is an inherent risk when getting around government blocks. Torrenters who get caught risk a fine, but some repressive governments may have a much worse penalty for you if you’re caught circumventing censorship. If unsure, it could be better to not take the risk and wait for better days. Whatever you decide, we hope you stay safe and those better days come soon.
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