Compression Uncompressing


Wonderful course just one small query .

Working with SHELL-II -----> File Compression and Archival ---> Compressing and Uncompressing ( 3:33 ) slide .

It appears to me that the output of bzip2 and bunzip2 makes sense where bzip2 compresses test.img where as bunzip2 uncompresses test.img.bz2 

But when I look at other two commands it does not make same sense when I compare output of gzip and gunzip . 

It should be 
gunzip test1.img.gz 
du -sh test1.img
99M test1.img

Also I find same issue when I compare xz and unxz . 
I was about the openion it should have been as below 

unxz test2.img.xz 
du -sh test2.img
99M test2.img

Can you please review and confirm whether my concerns are correct or I am missing anything ?

Nice course anyway and I wish we could had more advance courses as well ex RHCSA / RHCE / RHCA etc in same manner . The best thing about these courses is animation , simplicity and slow speed .

with best regards
Pradeep Nehe

Hi Dear,

When there’s need for a very fast compression, gzip is the clear winner. It has also very small memory footprint, making it ideal for systems with limited memory.

bzip2 creates about 15% smaller files than gzip. bzip2 compresses somewhat slower than gzip, but seems that it hasn’t prevented bzip2 from getting popular. Nowadays most source code is available as both gzip and bzip2 compressed tar archives.

For more clarifications kindly check the link below:

Kindly clarify the second point more so that I can help you properly.


Let me put my query in other way round .

Please have a look at the Page no 109 Title Compressing / Uncompressing .

I believe the output of LHS is correct where bzip2 , gzip and xz are listed.
But output of RHS looks wrong ( only bunzip2 looks correct )

Output on RHS gunzip and unxz looks same as output of gzip and xz . Hence to in my view output in RHS of gunzip and unxz looks wrong ( it should be opposite to that of gzip and xz )

Please verify this from the PDF first so you will understand my point of view and then the video of this respective section.

with best regards
Pradeep Nehe