How do you construct a read-write pipe with lua?

Question

I\'d like to do the equivalent of:

foo=$(echo \"$foo\"|someprogram)

within lua -- ie, I\'ve got a variable containing a bunch of text, and

Answer 1

There is nothing in the Lua standard library to allow this.

Here is an in-depth exploration of the difficulties of doing bidirectional communication properly, and a proposed solution:

if possible, redirect one end of the stream (input or output) to a file. I.e.:

fp = io.popen("foo >/tmp/unique", "w")
fp:write(anything)
fp:close()
fp = io.open("/tmp/unique")
x = read("*a")
fp:close()

You may be interested in this extension which adds functions to the os and io namespaces to make bidirectional communication with a subprocess possible.