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How to retain the header information of a file

 
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Old 12-04-2007
How to retain the header information of a file
Hi,

I am using Bash shell to create some data and these data would be piped out to a file, let say output.txt.

This output.txt I would like to add some extra header information such as comments, descriptions and general information on the text.

I would like to know how could I maintain this type of information. I did try out using append to a file. In other word,I created a file with initial description and comments on it. Then, these data I would append (using << output.txt).

However, one limitation of this is that the data would be keep adding on top of the file each time repeated command are executed. Anyone have idea to solve this?

Besides, another problem is by having this header, I would like to further extract the data from the output.txt without the description and comments. I tried using head and tail but it doesnt work automatically. In other words, let say description and comment I have as first 5 lines of the output.txt. Currently I extract out these data using cat output.txt|..<all the operation>. But I could not help but extracting the first 5 lines as well.

Please advise. Appreciate alot.


Thanks.

-Jason
 
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LEARN ABOUT DEBIAN

h5unjam

h5unjam(1)						      General Commands Manual							h5unjam(1)

NAME

       h5unjam - Extract the user block from a HDF5 file

SYNOPSIS

       h5unjam -i in_file.h5 [-u user_block | --delete] [-o out_file.h5]

DESCRIPTION

       h5unjam	splits	an  HDF5 file, writing the user block to a file or stdout and the HDF5 file to an HDF5 file with a header at byte 0 (i.e.,
       with no user block).

       If out_file.h5 is given, a new file is created with the in_file.h5 without the user block. In this case, infile.h5 is unchanged.

       If out_file.h5 is not specified, the user_block is removed and in_file.h5 is rewritten, starting at byte 0.

       If user_block is set, the user block will be written to user_block.  If user_block is not set, the user block (if any) will be  written	to
       stdout. If --delete is selected, the user block will not be not written.

EXAMPLE USAGE

       For an HDF5 file, with_ub.h5, with a user block, extract the user block to user_block.txt and the HDF5 file to wo_ub.h5.

	    h5unjam -i with_ub.h5 -u user_block.txt -i wo_ub.h5

RETURN VALUE

       h5unjam returns the size of the output file, or -1 if an error occurs.

CAVEATS

       This tool copies all the data (sequentially) in the file(s) to new offsets. For a large file, this copy will take a long time.

       The  most  efficient  way  to create a user block is to create the file with a user block (see H5Pset_user_block), and write the user block
       data into that space from a program.

       The user block is completely opaque to the HDF5 library and to the h5jam and h5unjam tools.  The user block is simply read or written as  a
       string  of  bytes,  which could be text or any kind of binary data.  It is up to the user to know what the contents of the user block means
       and how to process it.

       When the user block is extracted, all the data is written to the output, including any padding or unwritten data.

       This tool moves the HDF5 file through byte copies, i.e., it does not read or interpret the HDF5 objects.

SEE ALSO

       h5dump(1), h5ls(1), h5diff(1), h5import(1), gif2h5(1), h52gif(1), h5perf(1), h5jam(1).

																	h5unjam(1)