gpx-merge.sh

#!/usr/bin/env bash
# Author: github.com/danielhoherd
# License: MIT

if [[ $# -lt 2 ]] ; then
    echo "This script merges gpx files and requires at least two gpx files passed as arguments. Output file is merged.gpx";
    echo "Usage:  ${0##*/} <file_1.gpx> <file_2.gpx> [... <file_n.gpx]";
    exit 1;
fi

check_for_required_commands() {
  for command in "$@" ; do
    command -v "${command}" >/dev/null 2>&1 || missing_commands+=( "${command}" )
  done

  if [[ "${#missing_commands[@]}" -gt 0 ]] ; then
    date "+%FT%T%z ${0##*/} ABORT: missing commands: ${missing_commands[*]}"
    exit 1
  fi
}
export -f check_for_required_commands

check_for_required_commands gpsbabel

args=();
for file in "$@" ; do
    if [[ -f "$file" ]] || [[ -h "$file" ]] ; then
        args+=( "-f" "$file" );
    else
        echo "Skipping $file, it's not a file."
    fi
done;

if [[ ${#args[@]} -lt 4 ]] ; then
    echo "We don't have enough actual files to work with. Exiting."
    exit 1
fi

gpsbabel -i gpx "${args[@]}" -o gpx -F merged.gpx