Merge multiple XLS to a new CSV file from command line

merge-xls2csv.sh

#!/bin/bash

HEADER_START='ALL_HEADERS_START_WITH_THIS'
DELETE_PREVIOUS_CSV=true
FILE='merged-xls.csv'

if [ "$DELETE_PREVIOUS_CSV" == "true" ]; then
    rm -f *.csv
fi

unoconv -f csv *.xls

if [ -z "$HEADER_START" ]; then
    cat *.csv > "$FILE.tmp"
else
    grep -m 1 -h "^$HEADER_START" *.csv | head -1 > "$FILE.tmp"
    grep -hv "^$HEADER_START" *.csv >> "$FILE.tmp"
fi

if [ "$DELETE_PREVIOUS_CSV" == "true" ]; then
    rm -rf *.csv
fi

mv "$FILE.tmp" "$FILE"

exit 0