cubicweb #2231960 [cwctl] On-the-fly generation of pgpass file when doing postgres operations [open]

cubicweb-ctl should create on-the-fly a temp file usable as a pgpass file, and set the PGPASSFILE environment variable with connection informations gathered from the source config file before running postgresql commands (lie in db-dump command).

prioritynormal
typeenhancement
done in<not specified>
load0.500
load left0.500
closed by<not specified>