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                   Help notes for modis_update_luts.csh
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Usage: modis_update_luts.csh satellite_name [OPTIONS]

Options:

  -quiet                Don't print any messages unless a new LUT is found
  -disable-download     Disable auto-downloading of newer LUTs
  -disable-activation   Disable activation of downloaded LUTs
  -verbose-ftp          Enable verbose auto-download messages
  -retries n            Number of times to retry a failed download

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The modis_update_luts.csh script compares local MODIS L1B calibration LUTs
to those on an ftp server, and optionally downloads and activates newer
remote LUTs if they are found. This script can be run as a cronjob or
manually, to keep LUTs up-to-date.

If the script's -quiet mode is invoked, messages are only written to
stdout when newer LUTs are found on the server or in the case of an error.
This avoids unnecessary emails when the script is run as a cronjob. It is
recommended to run this script as a daily cronjob. Remember to invoke a
shell to run the script within cron in order to set the MODISL1DB
environment variables. Example daily crontab lines for csh shell users:

0 0 * * * /bin/csh -c "/path_to_scripts/modis_update_luts.csh aqua -quiet"
0 0 * * * /bin/csh -c "/path_to_scripts/modis_update_luts.csh terra -quiet"


*** IMPORTANT ***
After running this script, new LUTs will not be activated in currently
open xterms. To activate new LUTs in any currently open xterms, you must
'source' your main shell initialization file in each open window, e.g.:

> source ~/.bashrc (for bash shells)
> source ~/.cshrc  (for csh and some tcsh shells)
> source ~/.tcshrc (for some tcsh shells)

If a user decides to manually activate new LUTs, they must edit the text
files $DBHOME/scripts/modisl1db_env.bash and
$DBHOME/scripts/modisl1db_env.csh, changing the LUT environment variables:
AQUA_REFL_LUT, AQUA_EMIS_LUT, AQUA_QA_LUT, TERRA_REFL_LUT, TERRA_EMIS_LUT,
TERRA_QA_LUT. They must then source their main shell initialization file.

The default location of the calibration LUTs is in $SDSDATA/modisa/cal/
and $SDSDATA/modist/cal/. It is MANDATORY that all three LUTS (reflective,
emissive, and qa) reside in the same directory.

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Explanation of command line arguments:
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satellite_name (required)
Specify the satellite as either "aqua" or "terra" (case-insensitive).

-quiet (optional)
No messages are printed to stdout unless a newer LUT is found on the
remote server or an error occurs.

-disable-download (optional)
Disable the automatic download feature of new LUTs from the ftp server.

-disable-activation (optional)
Disable immediate activation of the downloaded LUTs, thus leaving the old
LUTs set as the default. A user can activate LUTs later as described above.

-verbose-ftp (optional)
Enable verbose wget output messages for all LUT downloads.

-retries n (optional) (default=4)
Number of times to retry a failed download before giving up. The wget ftp
client uses linear backoff, waiting 1, then 2, then 3 seconds, etc. after
each attempt.

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