11-09-2010
1. Extract the all data you need just one time, and store it in a file.
2. If you run 14 simultaneous processes it will take just one day.
3. The format of tar is an established standard. Nobody is hiding it from you.
google for 'gnu coreutils' and download the source code. In the tarball is the source for tar itself.
The problem is this:
tar stands for 'tape archive'. To get to file #99 in a tar file you have to actually completely read though files 1 -> 98 first. There is no file metadata like on a hard drive that allows direct access. The same applies once you get to the file you want. You have to read thru the file itself until you get to a given record. You cannot "fast forward" to a given record or a given file.
Modify the program to run in as many separate processes as is possible on your system without overloading it. Each process opens one tar file, gets one data set, writes the "variables" to disk or even better to a database table.
So, you now have the six values for every day. And in one small file.
Do you know how to extract a given file? What command are you using to get the grib file from a tarball?
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TAR(1) General Commands Manual TAR(1)
NAME
tar - archiver
SYNOPSIS
tar key [ file ... ]
DESCRIPTION
Tar saves and restores file trees. It is most often used to transport a tree of files from one system to another. The key is a string
that contains at most one function letter plus optional modifiers. Other arguments to the command are names of files or directories to be
dumped or restored. A directory name implies all the contained files and subdirectories (recursively).
The function is one of the following letters:
c Create a new archive with the given files as contents.
x Extract the named files from the archive. If a file is a directory, the directory is extracted recursively. Modes are restored if
possible. If no file argument is given, extract the entire archive. If the archive contains multiple entries for a file, the lat-
est one wins.
t List all occurrences of each file in the archive, or of all files if there are no file arguments.
r The named files are appended to the archive.
The modifiers are:
v (verbose) Print the name of each file treated preceded by the function letter. With t, give more details about the archive entries.
f Use the next argument as the name of the archive instead of the default standard input (for keys x and t) or standard output (for
keys c and r).
u Use the next (numeric) argument as the user id for files in the output archive. This is only useful when moving files to a non-Plan
9 system.
g Use the next (numeric) argument as the group id for files in the output archive.
EXAMPLES
Tar can be used to copy hierarchies thus:
{cd fromdir; tar c .} | {cd todir; tar x}
SOURCE
/sys/src/cmd/tar.c
SEE ALSO
ar(1), bundle(1), tapefs(1)
BUGS
There is no way to ask for any but the last occurrence of a file.
File path names are limited to 100 characters.
The tar format allows specification of links and symbolic links, concepts foreign to Plan 9: they are ignored.
TAR(1)