python subprocess(or related) - load psql dump, got error - '<' ignored

Question

I am using call method to load sql dump:

 call(["psql", "-U", "user", "name", "<", "pathtofile"])

This is directly logging into postgres and ignoring "<" and pathtofile.

 psql: warning: extra command-line argument "<" ignored

Answer 1

Use stdin keyword argument if you want redirection:

with open("pathtofile", "rb") as f:
    call(["psql", "-U", "user", "name"], stdin=f)

Answer 2

Try changing to this:

 call(["psql", "-U", "user", "name", "<", "pathtofile"], shell=True)
                                                       ^^^^^^^^^^^^

"<" is an input redirection operator, and must be interpreted by a shell. If you don't say shell=True , it's passed to psql as an argument, and psql has no idea what to do with it.

Edit: in general, what @falsetru suggested is a better approach, because passing arbitrary strings to shells can be dangerous. But if you need to use shell operations, shell=True is the way to do it.