How to use the command clamdscan (with examples)

Clamdscan is a command-line virus scanner that uses the ClamAV Daemon. It allows you to scan files and directories for vulnerabilities and provides various options for managing infected files. In this article, we will explore several use cases of the clamdscan command and provide examples for each.

Use case 1: Scan a file or directory for vulnerabilities

Code:

clamdscan path/to/file_or_directory

Motivation: This use case is useful when you want to check a specific file or directory for potential malware or vulnerabilities. It allows you to scan individual files or entire directories for any suspicious content.

Explanation: The command clamdscan is followed by the path to the file or directory you want to scan. Clamdscan will analyze the content and report any potential threats.

Example output:

/path/to/file_or_directory: OK

Use case 2: Scan data from stdin

Code:

command | clamdscan -

Motivation: This use case is handy when you want to scan data from stdin, such as the output of another command or a pipe. It allows you to scan the data without needing to save it to a file first.

Explanation: The pipe symbol | is used to redirect the output of the preceding command to the clamdscan command. The hyphen - represents stdin as the input source.

Example output:

/stdin: OK

Use case 3: Scan the current directory and output only infected files

Code:

clamdscan --infected

Motivation: This use case is helpful when you want to scan the current directory and quickly identify any infected files. It allows you to focus only on the files that are potentially harmful.

Explanation: The option --infected instructs clamdscan to output only the infected files found during the scan.

Example output:

/infected_file_1.txt: Win.Test.EICAR_HDB-1
/infected_file_2.txt: Win.Test.EICAR_HDB-2

Use case 4: Output the scan report to a log file

Code:

clamdscan --log path/to/log_file

Motivation: This use case is useful when you want to save the scan report to a log file for future reference or analysis. It allows you to keep a record of the scan results.

Explanation: The option --log specifies the path and filename for the log file. Clamdscan will generate a detailed report and save it to the specified file.

Example output:

The scan report is written to the specified log file.

Use case 5: Move infected files to a specific directory

Code:

clamdscan --move path/to/quarantine_directory

Motivation: This use case is important when you want to isolate infected files to prevent further damage to your system. It allows you to move the potentially harmful files to a designated quarantine directory.

Explanation: The option --move specifies the path to the quarantine directory. Clamdscan will detect and move any infected files found during the scan to the specified directory.

Example output:

The infected files are moved to the quarantine directory.

Use case 6: Remove infected files

Code:

clamdscan --remove

Motivation: This use case is crucial when you want to delete infected files that pose a threat to your system. It allows you to remove the malware-infected files from your system entirely.

Explanation: The option --remove instructs clamdscan to remove any infected files found during the scan.

Example output:

Infected files are successfully removed from the system.

Use case 7: Use multiple threads to scan a directory

Code:

clamdscan --multiscan

Motivation: This use case is beneficial when you want to improve the scan speed by utilizing multiple threads. It allows you to utilize multiple cores or processors to complete the scan faster.

Explanation: The option --multiscan enables clamdscan to use multiple threads for scanning a directory. This can significantly reduce the scan time, especially for large directories.

Example output:

The scan completes faster than a single-threaded scan.

Use case 8: Pass the file descriptor instead of streaming the file to the daemon

Code:

clamdscan --fdpass

Motivation: This use case is handy when you want to pass the file descriptor instead of streaming the entire file to the ClamAV Daemon. It can save network bandwidth and reduce latency.

Explanation: The option --fdpass allows clamdscan to send only the file descriptor instead of streaming the entire file to the ClamAV Daemon. This can improve the scanning efficiency, especially for large or network-mounted files.

Example output:

The scan completes faster with reduced network traffic.

Conclusion

Clamdscan is a powerful command-line virus scanner that provides various options for scanning files and directories. It offers flexibility in managing infected files, such as quarantining or removing them. By familiarizing yourself with the different use cases of the clamdscan command, you can efficiently secure your system against potential threats.