How do I use gdal command-line utility to extract raster attributes as input for gdalwarp?

Question

I need to reproject a raster into the same extent and resolution as an existing raster, and want to use the gdal command-line utilities to do it.

How do I extract these values in a format I can use as input for gdalwarp?

Here's what I've tried:

function gdal_extent_gdalwarp_te() {
    if [ -z "$1" ]; then
        echo "Missing arguments. Syntax:"
        echo "  gdal_extent <input_raster>"
        return
    fi
    EXTENT=$(gdalinfo "$1" |\
        grep "Lower Left\|Upper Right" |\
        sed "s/Lower Left  //g;s/Upper Right //g;s/).*//g" |\
        #tr "\n" " " |\
        sed 's/ *$//g' |\
        tr -d "\n[(,]'")
    echo -n "$EXTENT"
}

function gdal_pixelsize_gdalwarp_tr() {
    if [ -z "$1" ]; then
        echo "Missing arguments. Syntax:"
        echo "  gdal_pixelsize_gdalwarp_tr <input_raster>"
        return
    fi
    EXTENT=$(gdalinfo "$1" |\
        grep "Pixel Size" |\
        sed "s/Pixel Size =//g; s/,/ /g" |\
        tr "\n" " " |\
        tr -d "[(,])-")
    echo -n "$EXTENT"
}

ExtractedSRS=$(gdalsrsinfo -o proj4 "SRSraster.tif" | tr -d "'")
echo "d"
ExtractedExtent=$(gdal_extent_gdalwarp_te "SRSraster.tif")
echo "e"
ExtractedResolution=$(gdal_pixelsize_gdalwarp_tr "SRSraster.tif")

#in this case I'm trying to tile the input rasters into a new output raster
gdalwarp -t_srs "$ExtractedSRS" -te "$ExtractedExtent" -tr "$ExtractedResolution" inputrasters*.tif outputraster.tif

This gives the error:

Creating output file that is -124997P x 0L.
ERROR 1: Attempt to create -124997x0 dataset is illegal,sizes must be larger than zero.

If I try leaving out the -te option, like this,

gdalwarp -t_srs "$ExtractedSRS" -tr "$ExtractedResolution" inputrasters*.tif outputraster.tif

I get:

Usage: gdalwarp [--help-general] [--formats]
    [-s_srs srs_def] [-t_srs srs_def] [-to "NAME=VALUE"]
    [-order n | -tps | -rpc | -geoloc] [-et err_threshold]
    [-refine_gcps tolerance [minimum_gcps]]
    [-te xmin ymin xmax ymax] [-tr xres yres] [-tap] [-ts width height]
    [-wo "NAME=VALUE"] [-ot Byte/Int16/...] [-wt Byte/Int16]
    [-srcnodata "value [value...]"] [-dstnodata "value [value...]"] -dstalpha
    [-r resampling_method] [-wm memory_in_mb] [-multi] [-q]
    [-cutline datasource] [-cl layer] [-cwhere expression]
    [-csql statement] [-cblend dist_in_pixels] [-crop_to_cutline]
    [-of format] [-co "NAME=VALUE"]* [-overwrite]
    [-nomd] [-cvmd meta_conflict_value]
    srcfile* dstfile

Available resampling methods:
    near (default), bilinear, cubic, cubicspline, lanczos, average, mode.

FAILURE: Wrong value for -tr parameters.

Answer 1

The gdal command line utility to get the extent and the resolution of a raster is called gdalinfo. You can then parse those results if you want. Personnally, I prefer to use a Python script to get the information. See this answer here

Answer 2

It appears that my code was actually extracting the values correctly, but that I needed to drop the quotation marks when I actually ran gdalwarp.

This seems to work:

gdalwarp -t_srs "$ExtractedSRS" -te $ExtractedExtent -tr $ExtractedResolution -r bilinear inputrasters*.tif outputraster.tif