Chapter 7

Compression on a file works by:

• Removing redundant information

• Consolidating multiple files into one

• Eliminating gaps within the file

• Storing most of the data on removable media and just leaving a pointer

In general, for which of the following would you want to use lossless compression?

• An encrypted email

• An mp3 audio file

• A movie

• A log file

Lossy compression: (choose three)

• Sacrifices some quality

• Usually results better compression than lossless

• Is often used with documents

• Decompresses to an identical version as the original

• Is often used with images

You type gzip myfile.tar. What happens? (choose two)

• myfile.tar.gz holds a compressed version of myfile.tar

• myfile.tar is unarchived into the current directory

• myfile.tar is removed

• An error; you forgot to specify the file with –f

• An error; you forgot to pass the name of the output file

How would you obtain output similar to the following? compressed​​     ​​​uncompressed     ratio        uncompressed_name 278168                1016950                  72.6%           tags

• gunzip –t tags

• file tags

• gzip –l tags

• tar –czf tags

Which command would you use to archive the Documents directory and compress it with bzip2 compression?

• tar –czf documents.tbz Documents

• tar –cjf Documents

• tar –fzc Documents documents.tbz

• tar –cf Documents documents.tbz

• • tar –cjf documents.tbz Documents

Which flag would you pass to tar in order to have it make a new archive?

• -c

• -x

• –t

• –j

Which command will show what is inside the compressed tarball with a name of foo.tar.gz?

• tar –xf foo.tar.gz

• tar –tjf foo.tar.gz

• tar –tzf foo.tar.gz

• tar –lf foo.tar.gz

In the command tar –cvjf foo.tbz a b c, what are a, b, and c?

• File names to be added to the archive

• a is the directory that will be prepended to files; b and c are files inside it

• Matching operators; anything starting with a, b, or c will be added

• Extra flags passed to tar

Given the command tar –cvjf homedirs.tbz /home, which of the following are true? (choose two)

• The output file will be compressed

• The /home directory will be restored with the contents of homedirs.tbz

• The command will print out each filename as it is processed

• Files that are present in the archive might overwrite files in /home

• • Only files starting with /home will be extracted from the archive