Merge GPS multile tracks into one with gpsbabel

gistfile1.txt

#!/bin/zsh

# Initialize variables
files=""
directory="."
outputfn=""

# Function to show usage
usage() {
    echo "Usage: $0 -i <file_mask> [-o <filename>] [-d <directory>]"
    exit 1
}

# Parse command line options
while getopts ":i:d:" opt; do
    case $opt in
        i)
            file_mask="$OPTARG"
            ;;
        d)
            directory="$OPTARG"
            ;;
        o)
            outputfn="$OPTARG"
            ;;
        \?)
            echo "Invalid option: -$OPTARG" >&2
            usage
            ;;
        :)
            echo "Option -$OPTARG requires an argument." >&2
            usage
            ;;
    esac
done

# Check if mandatory parameters are provided
if [ -z "$file_mask" ]; then
    echo "Option -i is required."
    usage
fi
#fill outputfn from filemask
if [ -z "$outputfn" ]; then
    outputfn="${file_mask[1,10]}.gpx"
fi

# Check if directory exists
if [ ! -d "$directory" ]; then
    echo "Directory '$directory' does not exist."
    usage
fi

# Find files matching the mask in the directory and append them to the files variable
while IFS= read -r -d '' file; do
	echo $file
    files+="-f $file"$' '
done < <(find "$directory" -type f -name "$file_mask" -print0)

# Display found files
echo "Found files:"
echo "$files"

# Now, you can use the $files variable for further processing

startscr="/Applications/GPSBabelFE.app/Contents/MacOS/gpsbabel -w -r -t -i gpx $files -x sort,time -x track,pack,title=$outputfn -o gpx -F $outputfn"

echo "Saving into $outputfn"
eval "$startscr"