Diez B. Roggisch wrote: > Frank Millman wrote: > > Hi all > > > > I understand that StringIO creates a file-like object in memory. > > > > Is it possible to invoke another program, using os.system() or > > os.popen(), and use the < redirect operator, so that the other program > > reads my StringIO object as its input? > > No. Processes don't share memory - thus you have to either use a temp > file, or pipes. > > > BTW, I have tried using popen2() and passing my data via stdin, but the > > other program (psql) does not react well to this - again, I will give > > more info if necessary. > > Better do so :) > > Diez
Thanks, Steve and Diez, for the replies. I didn't think it was possible, but it was worth asking :-) I will try to explain my experience with popen() briefly. I have some sql scripts to create tables, indexes, procedures, etc. At present there are about 50 scripts, but this number will grow. I have been running them manually so far. Now I want to automate the process. I am supporting PostgreSQL and MS SQL Server, and the syntax is slightly different in some cases. Rather than maintain two sets of scripts, I prefix some lines with -pg- or -ms- to indicate the platform, and then use Python to parse the scripts and generate a correct output for each platform, passing it to 'psql' and 'osql' respectively, using popen(). I have had a few problems, but it would take too long to describe them all, and I just want a working solution, so I will focus on my latest attempt. I run through all the scripts and create a StringIO object with the string I want to pass. It is about 250 000 bytes long. If I run psql using popen(), and pass it the string via stdin, it works fine, but I get all the messages on the screen. If I do the same, but end the command with ' > fjm 2>&1' it works correctly and the messages end up in the file fjm, which is about 40 000 bytes long. If I run it with popen4(), it starts ok, but then hangs about 1/4 of the way through. Exactly the same happens on MSW. It seems to be hitting a limit on the size of the stdout file - is that possible? For my purposes, I will be happy to use popen() and a choice of no redirection, redirect to a file, or redirect to /dev/null. The question about popen4() is therefore academic, though I would be interested to know the answer. BTW, is there an equivalent of /dev/null on MSW? Thanks in advance for any suggestions. Frank -- http://mail.python.org/mailman/listinfo/python-list
