Check if two files are identical linux

LinuxOperating SystemOpen Source

29 Lectures 9 hours

Sonali Shrivastava

Let’s say that we have two files inside a directory called dir1, and at first both these files are different. Different in the sense that the text they contain isn’t the same.

The files in the folder −

The contents inside the first file(2.txt) looks something like this −

The contents inside the second file(2.txt) looks something like this −

We can easily make use of the diff command to check if they have something different. Consider the command shown below −

Output

But in case where the contents of the file are exactly the same, then the diff command won’t return any output.

In that case it is recommended to make use of the cmp command. The cmp command is a Linux utility command that is used to compare two files.

Command

Output

Updated on 29-Jul-2021 11:18:14

Probably the easiest way to compare two files is to use the diff command. The output will show you the differences between the two files. The signs indicate whether the extra lines are in the first () file provided as arguments.

How can I tell if two files are the same?

On the File menu, click Compare Files. In the Select First File dialog box, locate and then click a file name for the first file in the comparison, and then click Open. In the Select Second File dialog box, locate and then click a file name for the second file in the comparison, and then click Open.

How do I compare two files in UNIX?

There are 3 basic commands to compare files in unix:

1. cmp : This command is used to compare two files byte by byte and as any mismatch occurs,it echoes it on the screen. if no mismatch occurs i gives no response. …
2. comm : This command is used to find out the records available in one but not in another.
3. diff.

How can I compare two text files?

For all file formats that Word can open, the Compare option in Word is the easiest to use.

1. In the search box on the toolbar type Word. …
2. Select Word from the search options. …
3. On the MS Word toolbar click Review. …
4. In the Review menu, click Compare. …
5. From the two options available, select Compare…

WinDiff is a graphical file comparison program published by Microsoft (from 1992)., and is distributed with Microsoft Windows Support Tools, certain versions of Microsoft Visual Studio and as source-code with the Platform SDK code samples.

What does 2 mean in linux?

38. File descriptor 2 represents standard error. (other special file descriptors include 0 for standard input and 1 for standard output). 2> /dev/null means to redirect standard error to /dev/null . /dev/null is a special device that discards everything that is written to it.

How do I compare two bin files in linux?

If you want to compare two files byte by byte, you can use the cmp program with the –verbose ( -l ) option to show the values of each differing byte in the two files. With GNU cmp , you can also use the -b or –print-bytes option to show the ASCII representation of those bytes. See Invoking cmp , for more information.

Can Notepad ++ compare two files?

Open any two files (A, B) in Notepad++, which you want to compare. File B (new) gets compared to File A (old). Then, navigate to Plugins > Compare Menu > Compare. It shows the difference/comparison side by side, as shown in the screenshot.

File and Document Comparison Tools

• Kaleidoscope. Kaleidoscope lets you compare text documents (including source code) and images. …
• Workshare Compare. …
• Docu-Proof Enterprise. …
• ExamDiff. …
• Diff Doc. …
• Compare Suite. …
• WinMerge. …
• Araxis Merge.

Is there a diff command in Windows?

You can use the diff command to show differences between two files, or each corresponding file in two directories. diff outputs differences between files line by line in any of several formats, selectable by command line options. This set of differences is often called a `diff’ or `patch’.

Psssst:  How do you merge two files in UNIX?

What is WinMerge used for?

WinMerge is an Open Source differencing and merging tool for Windows. WinMerge can compare both folders and files, presenting differences in a visual text format that is easy to understand and handle.

Does Windows 10 have Windiff?

It works in Windows 10 but you might find problems from time to time. Whichever source you get it from, it is a very old tool that is no longer developed or supported.

Check for file verification between 2 files, no matter what operating system you are using.

When verifying if two files are identical, both must be the same, technically speaking, from the first byte to the last.

They can have different filenames, but essentially they are an exact duplicate of the other.

How do we prove that?

It is not practical to, for example, check all the contents of two lengthy Word documents or inspect every pixel for 2 similar file images.

Here are the 4 different ways to prove if two files are the same.

The fastest and most accurate method is to check if two files are identical, have the same content, and replicate the other.

Legally speaking, in a court of law, the use of both MD5 and SHA-1 hashing algorithms are scientifically accepted and widely used to determine if two digital files are exactly the same.

Both hashes are cryptographic hash functions, using mathematics to generate a 128-bit string value (for MD5) or a 160-bit string value.

You can generate a hash value for any text or paragraph, any digital file, e.g. image, video or documents, and even a transaction.

Below is an example of 2 similar images, using MD5 hashes to prove if they are the same file.

MD5 = 1CE434071294B9E7AEC68CA5191E2F87

MD5 = 1CE434071294B9E7AEC68CA5191E2F87

Both hash values are the same; therefore, both images are duplicate files without any difference or modifications.

For Windows

Using the Windows PowerShell command-line quickly without installing any additional tools since it is already in-built in the operating system.

Type “Powershell” into the Windows Search bar and open it.

Copy and paste the following code into the command prompt, changing the file path (highlighted in blue).

if((Get-FileHash "path-to-fileA").hash -eq (Get-FileHash "path-to-fileB").hash) {"Both Files Are Identical"} else {"Both Files Are NOT Identical"}

Change the “path-to-FileA” and “path-to-FileB” accordingly to the 2 files you want to test.

When 2 files are identical, the output will be “Both Files Are EXACTLY THE SAME”

HashMyFiles is a small utility tool that requires no installation (drag & drop files) and supports up to Windows 10.

It can calculate both MD5 and SHA-1 hash values.

For Mac

Open Terminal and enter this simple command below (changing the 2 files to your own).

md5 FileA.jpg FileB.jpg

When both file hashes match, they are exactly the same file.

You can also calculate SHA-1 hash using;

shasum -a 1 FileA FileB

For Linux

Open Terminal and enter this short command, pointing to your file, to generate your MD5 hash value.

md5sum filename.jpg

Use this method if you want to compare 2 different Word documents.

Regardless of the operating system you are using, the Microsoft Office Word application itself has a “Compare” feature we can use.

Note: this method is only used to compare the contents of both files and not to prove if they are the exact replicate of each other (exact bit-by-bit).

1) Open Word application,2) Click on the “Review” tab,3) Go to the “Compare” dropdown menu,

4) Choose “Compare Documents” and select the 2 Word Documents you want to verify.

When both files are the same, MS word will return a message box like this (below).

Use this method to compare 2 text files, source files, log files and SQL databases.

Notepad++ is a windows-only application that many programmers use to perform source-code editing.

It is a reliable replacement for the native Notepad application in Windows operating system.

Note: Similar to the MS Word method above, Notepad++ allows for comparing the contents for both files.

1) Open Notepad++ application2) Go to “Plugins” – “Plugin Manager” – “Show Plugin Manager”

3) Select the “Compare” plugin and click “Install”

Now, open the 2 files separately in 2 different Notepad++ applications.

From the “Plugins” menu, select “Compare” and again, select “Compare”

You can now see both files side-by-side, and if you notice any yellow highlight portion, this means these are the differences in content between both files

If the files or content you want to verify are not sensitive, you can opt to use these online services to check their authenticity.

DiffChecker allows for the comparison of text, images, PDF, Excel and even folders.

It is also available as a desktop app for Windows, Mac and Linux.

CopyLeaks

Similar to DiffChecker, you can copy the entire text content from 2 different files and paste it on Copyleaks for comparison to see if they are identical.

You can also upload the files or provide the URL address for Copyleaks to check.

OnlineMD5

OnlineMD5 is a simple online service to generate both MD5 and SHA-1 hash values.

You can paste your text content or easily upload a file for quick hash computation.

The maximum upload file size is 4GB.

With that, you could even hash an entire ISO image or even a video file.

5. Summary

To prove if 2 digital files are the exact copy of each other, always use a cryptographic hash like MD5 and SHA-1. It is the most accurate way to prove the authenticity of two digital files.

MD5 & SHA-1 hash algorithms are often used in a court of law to verify digital files.

To compare only the contents of two files, use the rest of the methods stated in this article.

Consider using any of the online hashing services mentioned above, when the files & contents are not sensitive to you.