Join CSV file to shapefile using gdal/ogr

The accepted answer is really useful, but I found that it was slow with a large-ish database. I believe it also limits your options when joining the data.

My method now is to pull everything into SQLite (using a combination of csvkit and ogr2ogr):

csvsql --db sqlite:///myjoindb.db --insert myjoincsv.csv
ogr2ogr -append -f "SQLite" myjoindb.db myjoinshp.shp

Then join everything and create a shapefile out of it:

ogr2ogr -f "ESRI Shapefile" -sql "SELECT csv.*, shp.* FROM myjoinshp shp INNER JOIN myjoincsv csv ON csv.joinfield = shp.joinfield" joined_output.shp myjoindb.db

Based on Eric's answer, this is an approach using the SQLite command instead of csvkit. If you're not already starting from a GeoPackage, convert to it first:

ogr2ogr -f GPKG myjoinshp.gpkg myjoinshp.shp

Then, exploiting the fact that a GeoPackage is actually an SQLite database, import the CSV as a new table (named myjoincsv), which modifies the existing GeoPackage:

sqlite3 myjoinshp.gpkg --cmd '.mode csv' '.import myjoincsv.csv myjoincsv'

This step could also be done in a GUI, e.g. DB Browser for SQLite supports importing a CSV into the loaded database by drag and drop.

Finally, make a new GeoPackage or shapefile, using a join, as in Eric's answer:

ogr2ogr -f GPKG joined_output.gpkg myjoinshp.gpkg -sql "SELECT shp.*, csv.* FROM myjoinshp shp JOIN myjoincsv csv ON shp.joinfield = csv.joinfield"