cksum command in Linux

The Linux cksum command is used to calculate a cyclic redundancy check (CRC) checksum for files. This checksum can be compared between systems to check for file integrity or changes. Additionally, cksum can also display the byte count of a file. By using the options available with cksum, users can control the output format and achieve the desired checksum calculation for their specific needs.

cksum Syntax:

cksum [option] [file(s)]

Linux cksum Options:

Option	Description
-help	Display a help message and exit
-b	Treat input as binary
-h	Print the checksum and the number of bytes in the input file

cksum Parameters:

Parameter	Description
file(s)	The file(s) to calculate the checksum for

How to use cksum command:

Calculate Checksum of a File

cksum file.txt

Calculate the checksum of the file “file.txt”.

Calculate Checksum of Multiple Files

cksum file1.txt file2.txt file3.txt

Calculate the checksum of multiple files simultaneously.

Verify File Integrity with Checksum

cksum -c checksums.txt

Verify the integrity of files listed in the checksums.txt file.

Generate Checksum in Different Format

cksum -b file.txt

Generate the checksum of a file in binary format.

Display Only The Checksum Value

cksum -s file.txt

Display only the checksum value without filename.

Checksum for a Specific Number of Bytes

cksum -n 100 file.txt

Generate checksum for the first 100 bytes of the file.

Recursive Checksum Calculation

cksum -r folder/

Calculate checksum recursively for all files in a folder.

Ignore Linefeed Characters

cksum -L file.txt

Calculate checksum with ignoring linefeed characters.

How do I use cksum in Linux?

To use the cksum command in Linux, execute the following command:

cksum file.txt

How do I calculate a checksum for multiple files in Linux?

To calculate the checksum for multiple files in Linux, you can use the following command format:

cksum file1.txt file2.txt file3.txt

How can I display the checksum value only in cksum?

You can display only the checksum value in cksum by using the following command:

cksum -s file.txt

How do I include the checksum byte count in the cksum output?

To include the checksum byte count in the cksum output, you can use the following command:

cksum -o file.txt

How do I suppress the output of file names in cksum?

To suppress the output of file names in cksum and only display the checksum and byte count, use the following command:

cksum -q file.txt

How can I verify the integrity of a file using cksum?

To verify the integrity of a file using cksum, you can compare the generated checksum with the original checksum. Here’s an example:

original=$(cksum file.txt | cut -d' ' -f1)
generated=$(cksum file.txt | cut -d' ' -f1)
if [ $original == $generated ]; then
    echo "Integrity verified"
else
    echo "Integrity check failed"
fi

How do I generate a checksum using a string input with cksum?

To generate a checksum using a string input with cksum, you can use echo to pass the string and pipe it to cksum. Here’s an example:

echo "Hello, World!" | cksum

How can I recursively calculate checksums for all files in a directory in Linux?

You can recursively calculate checksums for all files in a directory in Linux using the find command in combination with xargs and cksum. Here’s an example:

find /path/to/directory -type f | xargs cksum

How do I calculate the checksum without checking for ASCII control characters?

To calculate the checksum without checking for ASCII control characters using cksum, you can use the following command:

cksum -B file.txt

Applications of the cksum command

Verifying data integrity
Checking for file corruption
Generating checksum values for files
Comparing checksum values for files
Detecting changes in files
Ensuring data consistency
Validating file transfer accuracy