tar(1) zxf foo.tgz bar
The GNU version of the tar archiving utility
-z, --gzip, --gunzip --ungzip
-x, --extract, --get
      extract files from an archive
-f, --file ARCHIVE
      use archive file or device ARCHIVE
-b, --blocking-factor BLOCKS
      BLOCKS x 512 bytes per record
-a, --auto-compress
      use archive suffix to determine the compression program
-r, --append
      append files to the end of an archive
source manpages: tar