What it is
bzip2 is a high-quality data compression library and tool that uses the Burrows-Wheeler algorithm and Huffman coding. It provides better compression ratios than traditional gzip for many types of files.
bzip2 provides both a command-line tool for file compression and a C library (libbz2) for programmatically compressing/decompressing data streams. It supports streams, file-level compression, and integration with other tools like tar.
Installation
sudo apt install libbz2-dev bzip2Getting started
The smallest useful thing you can do with it, and what each part means.
bzip2 myfile.txtbunzip2 myfile.txt.bz2Advanced usage
Where the library earns its place over a simpler alternative.
#include <bzlib.h>
#include <stdio.h>
int main() {
FILE *source = fopen("input.txt", "rb");
FILE *dest = fopen("output.bz2", "wb");
BZFILE *bz = BZ2_bzWriteOpen(NULL, dest, 9, 0, 30);
char buffer[1024];
int n;
while ((n = fread(buffer, 1, sizeof(buffer), source)) > 0) {
BZ2_bzWrite(NULL, bz, buffer, n);
}
BZ2_bzWriteClose(NULL, bz, 0, NULL, NULL);
fclose(source);
fclose(dest);
return 0;
}#include <bzlib.h>
#include <stdio.h>
int main() {
FILE *source = fopen("output.bz2", "rb");
FILE *dest = fopen("restored.txt", "wb");
BZFILE *bz = BZ2_bzReadOpen(NULL, source, 0, 0, NULL, 0);
char buffer[1024];
int n;
while ((n = BZ2_bzRead(NULL, bz, buffer, sizeof(buffer))) > 0) {
fwrite(buffer, 1, n, dest);
}
BZ2_bzReadClose(NULL, bz);
fclose(source);
fclose(dest);
return 0;
}Errors and fixes
The failures you are most likely to hit, and what actually resolves them.
- BZ_CONFIG_ERROR
- Occurs if library configuration is invalid. Ensure libbz2 is compiled and linked correctly.
- BZ_IO_ERROR
- Indicates a file I/O problem. Verify file paths, permissions, and disk space.
- BZ_MEM_ERROR
- Memory allocation failed. Consider using smaller buffers or freeing memory before compression.
Best practices
- Choose an appropriate compression level (1–9) based on speed vs size trade-off.
- Use streaming APIs for large files to reduce memory usage.
- Close all file handles and BZFILE objects properly to avoid corruption.
- Use file extensions `.bz2` for compressed files for clarity.
- Combine with tar (tar.bz2) for archiving multiple files efficiently.
Background
Why it exists, and what it was reacting to.
bzip2 was developed by Julian Seward in 1996–1998 as an open-source compression library and command-line tool. It became popular for compressing large datasets in Unix-like systems due to its high compression efficiency and simplicity.