Get the Best Compression Possible with bzip2

Get the Best Compression Possible with bzip2

-[0-9]

Just as with zip and gzip, it's possible to adjust the level of compression that bzip2 uses when it does its job. The bzip2 command uses a scale from 0 to 9, in which 0 means "no compression at all" (which is like tar, as you'll see later), 1 means "do the job quickly, but don't bother compressing very much," and 9 means "compress the heck out of the files, and I don't mind waiting a bit longer to get the job done." The default is 6, but modern computers are fast enough that it's probably just fine to use 9 all the time.

$ ls -l -rw-r--r-- scott scott 1236574 moby-dick.txt $  bzip2 -c -1 moby-dick.txt > moby-dick.txt.bz2 $ ls -l -rw-r--r-- scott scott 1236574 moby-dick.txt -rw-r--r-- scott scott  424084 moby-dick.txt.bz2 $  bzip2 -c -9 moby-dick.txt > moby-dick.txt.bz2 $ ls -l -rw-r--r-- scott scott 1236574 moby-dick.txt -rw-r--r-- scott scott  367248 moby-dick.txt.bz2 

From 424KB with 1 to 367KB with 9that's quite a difference! Also notice the difference in ultimate file size between gzip and bzip2. At -9, gzip compressed moby-dick.txt down to 488KB, while bzip2 mashed it even further to 367KB. The bzip2 command is noticeably slower than the gzip command, but on a fast machine that means that bzip2 takes two or three seconds longer than gzip, which frankly isn't much to worry about.

Note

If you want to be clever, define an alias in your .bashrc file that looks like this:

alias bzip2='bzip2 -9' 

That way, you'll always use -9 and won't have to think about it.