read-fits-tape

#!/bin/bash

# Use the TAPE envar by default
tapedev="${TAPE:-/dev/nst0}"

# Default base name of 'fitstape'
basename='fitstape'

# Tape block size for FITS files
blocksize=28800

function helpme {
    echo "read-fits-tape"
    echo "Extracts all FITS files from a FITS tape into current directory"
    echo ""
    echo "Usage: $0 [-f <tapedev>] [-b <basename>]"
    echo ""
    echo "    -f  Path to tape device (Def: /dev/nst0)"
    echo "    -b  Base filename for extracted files (Def: fitstape)"
    echo ""
}
while getopts "hf:b:" opt ; do
    case "$opt" in
    	f)	tapedev="$OPTARG"
		;;
	b)	basename="$OPTARG"
		;;
	h)	helpme
		exit
		;;
	*)	echo "Unknown option: $opt" >&2
		helpme
		exit 1
		;;
    esac
done

if [ -z "$1" ]; then
    read -n 1 -p "Will read FITS tape from $tape. Proceed (y/n)? " yorn
    case "$yorn" in
    	n|N)	echo -e "\nAborting!"
		exit 1
		;;
	*)	echo -e "\nContinuing with default settings..."
		;;
    esac
fi

# Error out if we don't have perms on the tape device
if ! [ -r "$tapedev" ]; then
    echo "Error: cannot read from tape device $tapedev" >&2
    exit 1
fi

# Set variable blocksize
if ! mt -f "${tapedev}" setblk 0 ; then
    echo -e "WARNING: Unable to set tape blocksize. Read errors may occur.\n"
fi

file=0
seqnum=$(printf "%05d" $file)
outfile="${basename}-${seqnum}.fits"
if [ -f "${outfile}" ]; then
    echo "Error: Cowardly refusing to overwrite exiting file $outfile" >&2
    exit 1
fi
echo "Reading file $file from $tapedev..."
while dd if="${tapedev}" of="${outfile}" bs=$blocksize >/dev/null; do
    file=$(( $file +1 ))
    seqnum=$(printf "%05d" $file)
    outfile="${basename}-${seqnum}.fits"
    if [ -f "${outfile}" ]; then
	echo "Error: Cowardly refusing to overwrite exiting file $outfile" >&2
	exit 1
    fi
    echo "Reading file $file from $tapedev..."
done

echo "Done reading files from $tapedev"
echo "$file files read from tape"