Are you using Python for your automated workflow? Although you specify gdalinfo in your question, you can get the raster information using Python if you have the GDAL Python bindings set up.
# Open raster in ReadOnly mode
rast_src = ".../raster.tif"
rast_open = gdal.Open(rast_src, GA_ReadOnly)
# Get georeference information: this returns a list containing
# origin x, cell size (W-E),rotation, origin y, rotation, cell size (N-S)
rast_info = rast_open.GetGeoTransform()
# The origin is the top left of the image and the cell size is given in
# the x direction (W-E) and y direction (N-S).
res_x = rast_info
res_y = rast_info
Note that res_y will be negative as it is measured south from origin.
For more information on the GeoTransform object see the Getting Dataset Information section here: http://www.gdal.org/gdal_tutorial.html
The following tutorial essentially runs through this step by step and references some more useful online resources: http://geoinformaticstutorial.blogspot.co.uk/2012/09/reading-raster-data-with-python-and-gdal.html