How to use the command 'fc' (with examples)

The ‘fc’ command in Windows is a powerful tool designed to compare the contents of two files or sets of files. Whether you are looking for the slightest difference in code, text, or binary data, the ‘fc’ command can help determine exactly where the files diverge. It is immensely useful for developers, system administrators, and anyone managing large sets of files who need a quick and efficient way to spot discrepancies. Below are several use cases illustrating the versatility of the ‘fc’ command.

Compare 2 specified files:

Code:

fc path\to\file1 path\to\file2

Motivation:

This basic use case allows you to determine the differences between two specified files, which is critical when tracking changes or debugging issues. By directly comparing two files, you can quickly see exactly what has been added, removed, or altered without manually scanning through the text yourself.

Explanation:

• fc: The command initiates the file comparison process.
• path\to\file1 and path\to\file2: These arguments specify the paths to the files you want to compare.

Example Output:

Comparing files path\to\file1 and path\to\file2
***** path\to\file1
My name is John Doe.
***** path\to\file2
My name is Jane Doe.
*****

Perform a case-insensitive comparison:

Code:

fc /c path\to\file1 path\to\file2

Motivation:

A case-insensitive comparison is essential when the case doesn’t matter but you want to ensure the content is fundamentally the same. This is particularly useful in environments where case sensitivity is not enforced, such as Windows.

Explanation:

• /c: This flag tells the command to ignore the case differences between text characters.
• path\to\file1 and path\to\file2: Paths to the files to be compared without considering case differences.

Example Output:

Comparing files path\to\file1 and path\to\file2
(No differences encountered)

Compare files as Unicode text:

Code:

fc /u path\to\file1 path\to\file2

Motivation:

When dealing with files encoded in Unicode, such as those including special characters from various languages, it’s crucial to interpret the files correctly to find meaningful differences.

Explanation:

• /u: This option tells ‘fc’ to treat the files as Unicode text.
• path\to\file1 and path\to\file2: The files to be compared as Unicode text documents.

Example Output:

Comparing files path\to\file1 and path\to\file2
***** path\to\file1
Hello, 世界
***** path\to\file2
Hello, World
*****

Compare files as ASCII text:

Code:

fc /l path\to\file1 path\to\file2

Motivation:

For situations where you need to compare simple text files that are encoded in ASCII, this method ensures an accurate track of all textual differences without misinterpretation of text format.

Explanation:

• /l: Signals the command to consider files as ASCII text.
• path\to\file1 and path\to\file2: Indicate the files meant for ASCII comparison.

Example Output:

Comparing files path\to\file1 and path\to\file2
***** path\to\file1
Rain fell heavily.
***** path\to\file2
rain fell heavily.
*****

Compare files as binary:

Code:

fc /b path\to\file1 path\to\file2

Motivation:

Binary comparison checks the file at the byte level, which is indispensable for verifying integrity or ensuring that two executable files or images are exactly identical.

Explanation:

• /b: This parameter commands the ‘fc’ utility to perform a byte-by-byte file comparison.
• path\to\file1 and path\to\file2: Files to be evaluated in binary format.

Example Output:

Comparing files path\to\file1 and path\to\file2
00000007: 6B 6A

Disable tab-to-space expansion:

Code:

fc /t path\to\file1 path\to\file2

Motivation:

In files where formatting relies heavily on tabs instead of spaces, preserving their exact form is crucial for accurate comparison, especially when such layout consistency is necessary.

Explanation:

• /t: Stops the command from converting tabs to spaces during comparison, preserving the exact formatting of the original text.
• path\to\file1 and path\to\file2: Specify files that may contain tabs that need to be compared directly.

Example Output:

Comparing files path\to\file1 and path\to\file2
***** path\to\file1
Column1	Column2
***** path\to\file2
Column1    Column2
*****

Compress whitespace (tabs and spaces) for comparisons:

Code:

fc /w path\to\file1 path\to\file2

Motivation:

Sometimes, files containing erratic amounts of whitespace or indents can appear different when they are not, especially when dealing with code or formatted text. This option allows you to focus solely on the content without being blinded by whitespace discrepancies.

Explanation:

• /w: This option adjusts the command to compress all whitespace, treating consecutive spaces and tabs as a single space.
• path\to\file1 and path\to\file2: The files being compared with whitespace compressed.

Example Output:

Comparing files path\to\file1 and path\to\file2
(No differences encountered)

Conclusion:

The ‘fc’ command is a versatile utility for file comparison in Windows, offering various options that allow users to tailor their file comparison needs to the nature of their files and the sensitivity of the differences they wish to identify. Whether you’re comparing text files, executable binaries, or anything in between, this tool is integral in facilitating the management and integrity of files.