Re: obtaining process exit code from popen()

[steve donovan <steve.j.donovan@...>]

On Sat, Jun 6, 2009 at 11:54 AM, steve
donovan<steve.j.donovan@gmail.com> > This is a fuller elaboration of
the hack; you get the status code any
> way (because you will need to strip it out with some pattern)

Just for the record, this version covers most of the cases; it
redirects stderr, so that you can use to capture the full output of
'gcc' say.

function command(cmd,no_lf)
    local f = io.popen(cmd..' 2>&1; echo "-retcode:$?"' ,'r')
    local l = f:read '*a'
    f:close()
    local i1,i2,ret = l:find('%-retcode:(%d+)\n$')
    if no_lf and i1 > 1 then i1 = i1 - 1 end
    l = l:sub(1,i1-1)
    return l,tonumber(ret)
end

res,ret = command (arg[1],true)
print('result "'..res..'"')
print('retcode',ret)

Now the next question was whether it this can be done on Windows.
Not..quite. It has all the bits, you can do the '2>&1' trick (I didn't
know that!), the command separator is '&' not ';', and '%ERRORLEVEL%
does give the return code of the last command. Unfortunately, its
value is not updated immediately in compound commands! I will leave
this to the last surviving Windows power users ;)

It is a hack, true, but that's why it needs to be hidden in a library

steve d.