python - Calling rm from subprocess using wildcards does not remove the files

Question

I'm trying to build a function that will remove all the files that start with 'prepend' from the root of my project. Here's what I have so far

def cleanup(prepend):
    prepend = str(prepend)
    PROJECT_ROOT = os.path.abspath(os.path.dirname(__file__))
    end = "%s*" % prepend
    cmd = 'rm'
    args = "%s/%s" % (PROJECT_ROOT, end)
    print "full cmd = %s %s" %(cmd, args)
    try:
        p = Popen([cmd, args],  stdin=PIPE, stdout=PIPE, stderr=PIPE, close_fds=True).communicate()[0]
        print "p", p
    except Exception as e:
        print str(e)

I'm not having any luck -- it doesn't seem to be doing anything. Do you have any ideas what I might be doing wrong? Thank you!

Answer 1

The problem is that you are passing two arguments to subprocess.Popen: rm and a path, such as /home/user/t* (if prefix is t). Popen then will try to remove a file named exactly this way: t followed by an asterisk at the end.

If you want to use Popen with the wildcard, you should pass the shell parameter as True. In this case, however, the command should be a string, not a list of arguments:

Popen("%s %s" % (cmd, args), shell=True, stdin=PIPE, stdout=PIPE, stderr=PIPE, close_fds=True)

(Otherwise, the list of arguments will be given to the new shell, not to the command)

Another solution, safer and more efficient, is to use the glob module:

import glob
files = glob.glob(prepend+"*")
args = [cmd] + files
Popen(args,  stdin=PIPE, stdout=PIPE, stderr=PIPE)

All in all, however, I agree that levon solution is the saner one. In this case, glob is the answer too:

files = glob.glob(prepend+"*")
for file in files:
    os.remove(file)