COMET Case Study
Library:
Extracting COMET Case Study Data
In order to position the tape to list the contents or to extract the data in the remaining tar files, you use the "mt" command. This will "fast-forward" the tape to the file you are interested in and then you can "tar" the data file(s).
Once you are familiar with the file structure on the tape (see Part III), the tape device name, and space available on your disk, you can begin extracting data for the case studies.
First, fast-forward to the desired tar file. You'll find a listing of the tar files for the case in the 8mm Data Tape Structure page for each case. Below is a description and an example of the use of the "mt" command:
mt -t /dev/rmt/c210d4hbn (where the "n" is for NO-REWIND) fsf <number of files you want to skip>
mt -t /dev/rmt/0hbn fsf 2
This would skip the first two tar files, and position the tape at tar file number 3.
You may wish to have a table of contents written to your screen before actually writing data to your disk. In the examples below, replace the "x" in -xvf with a "t". This will list the contents, and could take a very long time, so you may want to issue:
<cntrl> c
To stop the listing. You can also use this command to stop the data extraction.
To extract data from the tape, after you have fast-forwarded to the desired tar file, type:
tar -xvf /dev/rmt/<device name> <directories> <enter>
If you do not list specific directories, everything in that tar file will be extracted. This could very well fill up your disk, so I recommend you untar specific directories. Examples:
mt -t /dev/nrst9 fsf 2
tar -xvf /dev/rst9 12mar93/gempak/grids <enter>
This will retrieve the GEMPAK format gridded data files that you can use to run GEMPAK programs or to create your own metafiles.
mt -t /dev/rmt/0hbn fsf 3 tar -xvf /dev/rmt/0hb 13mar93/meta/rgl <enter>
In this example, you would extract the NTRANS metafiles for the NCEP Nested Gridded Model only. If you wanted metafiles for all the models, simply leave off the "rgl" in the above example.
mt -t /dev/rmt/c201d4hbn fsf 1
tar -xvf /dev/rmt/c201d4hb 11mar93/images/sat/GOES-8/24km/IR <enter>
The above command would extract 24 km resolution infrared satellite images from GOES-8. These images could be displayed in NSAT or directly by GEMPAK programs (set SATFIL=<image file name>).
mt -t /dev/nrst8 fsf 3
tar -xvf /dev/rst9 04jan95/images/radar/nids/CLE <enter>
This would extract WSR 88-D Level III radar products for Cleveland, OH.
IMPORTANT NOTE: If you are extracting data from the /nids directory, you must create a "link" in order for NSAT to find and display images. To do this, after you have extracted the data above, type:
cd ddmmmyy/images/sat <enter>
ln -s ../radar/nids NIDS <enter>
cd ../../ <enter>
This will take you to the level you need to run ntl display software.
|
|