Testing if ZSH parameters exist with IF & ELSE.

readme.markdown

I was looking for a way to simplify the following process:

1. Have a CSV projected in EPSG:26919
2. Convert it to a GeoJSON
3. Reproject that GeoJSON to EPSG:4326

It's a very common pattern, and I don't like retyping it. These are the 'solutions' to that problem.

zshTest-complex.sh

#!/bin/zsh 
# via http://gis.stackexchange.com/questions/68464/making-development-patterns-more-efficient-with-zsh?noredirect=1#comment93125_68464

usage(){
    usage="$0 infilepath {-o originalProjection} {-n newProjection}"
    echo "Usage: $usage"
    exit 1
}

orig_proj="some EPSG code"
new_proj="another EPSG code"

if [ -z "$1" ];then                           # Is filepath zero length?
    echo "Error: Filepath is required"
    usage
else
    case ${arg} in
        o) echo "Error: Filepath is required"
           usage
        ;;
        n) echo "Error: Filepath is required"
           usage
        ;;
    esac
    filepath=$1
fi

shift #Get rid of $1 so getopts picks up the other parameters
while getopts ':o:n:' arg
do
    case ${arg} in
        o) orig_proj=${OPTARG};;
        n) new_proj=${OPTARG};;
    esac
done

csv2geojon $filepath > ${filepath%.*}.geojson #the %.* bit strips off the file ext.
ogr2ogr -F geojson -s_srs epsg:$orig_proj -t_srs epsg:$new_proj \
     ${filepath%.*}_$new_proj.geojson ${filepath%.*}.geojson

zshTest-simple.sh

zshtest() {
  if [ -z "$1" ]; then
    echo 'no parameter specified'
  else
    echo $1;
  fi
}