Accessing environment variables from psql

Is there a way to access environment variables from psql? I can't find
any documentation on how to do this:

leif=> \! echo $IMPORTDIR
/home/leif/slekta/import/scripts
leif=> \i $IMPORTDIR/test.sql
$IMPORTDIR/test.sql: No such file or directory
leif=> \i $(IMPORTDIR)/test.sql
$(IMPORTDIR)/test.sql: No such file or directory
leif=> \i ${IMPORTDIR}/test.sql
${IMPORTDIR}/test.sql: No such file or directory
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Leif Biberg Kristensen
http://solumslekt.org/