python function run_pipe_line()

[Skaperen]

file runpipeline.py:

def run_pipe_line(*a):
    from subprocess import PIPE, Popen
    if len(a) == 1 and isinstance(a[0],(list,tuple)):
        # a list of commands instead of one per arg
        a = a[0]
    l = len(a)
    if l < 1: # if no commands then no results
        return []
    if l < 2: # if just one command then just do it
        p = [Popen(a[0])]
    else:
        for n in range(l):
            if n < 1: # if this is first command
                p = [Popen(a[0],stdout=PIPE)]
            elif n == l-1: # if this is last command
                p.append(Popen(a[l-1],stdin=p[n-1].stdout))
            else:
                p.append(Popen(a[n],stdin=p[n-1].stdout,stdout=PIPE))
    r = []
    for n in range(l): # wait for all and collect results
        r.append(p[n].wait())
    return r

a command is a list of strings (arguments, tokens). a pipeline is either a list of commands or a command per function call argument. so you might have commands in cmd1, cmd2, and cmd3 ... you can do either run_pipe_line([cmd1,cmd2,cmd3]) or just run_pipe_line(cmd1,cmd2,cmd3).