Yes, you can absolutely pipe command output directly to bzip2 for compression. The proper syntax would be:

command | bzip2 > outputfile.bz2

For your specific example with cat:

cat somefile.txt | bzip2 > somefile.txt.bz2

bzip2 is designed to read from stdin when no input file is specified. The pipe operator (|) connects the stdout of the left command to stdin of bzip2, while the redirect operator (>) writes the compressed output to a file.

Here are some common use cases:

# Compress MySQL dump
mysqldump -u user -p database | bzip2 > backup.sql.bz2

# Compress log files
cat /var/log/syslog | bzip2 > syslog.bz2

# Compress tar output
tar cf - directory/ | bzip2 > archive.tar.bz2

You can control compression level (1-9) with the - flag:

dd if=/dev/sda | bzip2 -9 > disk_image.bz2

For parallel compression (if your system supports pbzip2):

make | pbzip2 > build_output.bz2

Always check exit status when piping:

command | bzip2 > output.bz2 && echo "Success" || echo "Failed"

---

In Unix-like systems, piping command output to compression utilities like bzip2 is a fundamental technique for efficient data processing. The bzip2 compression algorithm offers excellent compression ratios, especially for text data, making it ideal for log files, text documents, and other compressible data.

The correct syntax for piping command output to bzip2 is:

command | bzip2 > output_file.bz2

For example, to compress a text file:

cat large_log.txt | bzip2 > compressed_log.bz2

When working with command output that needs compression, you have several options:

Compressing Direct Command Output

ls -l /var/log | bzip2 > directory_listing.bz2

Compressing Multiple Files

tar cf - *.log | bzip2 > all_logs.tar.bz2

Stream Processing with Compression

grep "error" system.log | bzip2 > errors_only.bz2

While piping, you can still use bzip2's options:

# Use faster compression (less CPU)
dd if=/dev/sda | bzip2 -1 > disk_image.bz2

# Use maximum compression (more CPU)
mysqldump database | bzip2 -9 > backup.sql.bz2

For more control over the compression process, you might consider:

Using Temporary Files

command > temp_file
bzip2 temp_file -c > final_output.bz2
rm temp_file

Parallel Compression

command | pbzip2 > output.bz2

Remember that:

• bzip2 is CPU-intensive compared to gzip
• Piping avoids temporary file creation
• Compression level affects both speed and ratio

Always check for errors in your pipeline:

if ! command | bzip2 > output.bz2; then
    echo "Compression failed" >&2
    exit 1
fi