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Full Discussion: What does this command do?
Top Forums UNIX for Beginners Questions & Answers What does this command do? Post 302981334 by jlliagre on Saturday 10th of September 2016 09:22:32 AM
Old 09-10-2016
This function doing what its name and message states, it checks if the first column of the file passed as an argument contains sorted and unique values otherwise output an error message and exit in failure.

The function code could have been written a more pedagogical way but conciseness was preferred. Here is a more readable variant:

Code:
check_sorted_and_uniq() {
  if ! cmp  <(awk '{print $1}' $1 | sort | uniq) <(awk '{print $1}' $1); then
    echo "$0: file $1 is not in sorted order or has duplicates"
    exit 1;
  fi
}

The "<(...)" syntax creates a transient file that is passed to the program as an argument and which contains the result of the command being inside the parenthesis.

Note that "awk '{print $1}' $1" is simply outputting the first column of the file passed as first argument. "$1" has totally different meanings for awk and for the shell.
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LEARN ABOUT DEBIAN

h5fromh4

H5FROMH4(1)							      h5utils							       H5FROMH4(1)

NAME

       h5fromh4 - convert HDF4 scientific datasets to an HDF5 file

SYNOPSIS

       h5fromh4 [OPTION]... [HDF4FILE]...

DESCRIPTION

       h5fromh4  takes one or more files in HDF4 format and outputs files in HDF5 format containing the datasets from the HDF4 files.  (Currently,
       only a single dataset per HDF4 file is converted.)

       HDF4 and HDF5 are free, portable binary formats and supporting libraries developed by the National Center for  Supercomputing  Applications
       at the University of Illinois in Urbana-Champaign.

       A  single  h5 file can contain multiple data sets; by default, h5fromh4 creates a dataset called "data", but this can be changed via the -d
       option, or by using the syntax HDF5FILE:DATASET with the -o option.  The -a option can be used to append new datasets to an  existing  HDF5
       file.   If the -o option is used and multiple HDF4 files are specified, all the HDF4 datasets are output into that HDF5 file with the input
       filenames (minus the ".hdf" suffix) used as the dataset names.

       The most basic usage is something like 'h5fromh4 foo.hdf', which will output a file foo.h5 containing the scientific dataset from foo.hdf.

OPTIONS

       -h     Display help on the command-line options and usage.

       -V     Print the version number and copyright info for h5fromh4.

       -v     Verbose output.

       -a     If the HDF5 output file already exists, append the data as a new dataset rather than overwriting the file  (the  default	behavior).
	      An existing dataset of the same name within the file is overwritten, however.

       -o file
	      Send  HDF5 output to file rather than to the input filename with .hdf replaced with .h5 (the default).  If multiple input files were
	      specified, this causes all input datasets to be stored in file (rather than in separate files), with the input filenames (minus  the
	      .hdf suffix) as the dataset names.

       -d name
	      Write  to  dataset  name	in  the  output; otherwise, the output dataset is called "data" by default.  Alternatively, use the syntax
	      HDF5FILE:DATASET with the -o option.

BUGS

       Send bug reports to S. G. Johnson, stevenj@alum.mit.edu.

AUTHORS

       Written by Steven G. Johnson.  Copyright (c) 2005 by the Massachusetts Institute of Technology.

h5utils 							   March 9, 2002						       H5FROMH4(1)
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