Code snippet to find existence of a database in postgresql u

db= "apdb"
c1 = "psql -U postgres -lqt"
c2 = "cut -d | -f 1"
c3 = "grep -w " + db

ps1 = subprocess.Popen(c1.split(),stdout=subprocess.PIPE)
ps2 = subprocess.Popen(c2.split(),stdin=ps1.stdout, stdout=subprocess.PIPE)
ps3 = subprocess.Popen(c3.split(),stdin=ps2.stdout , stdout=subprocess.PIPE)
result = ps3.communicate()[0]  # if empty , db not found
result = result.strip()