does this mean ....

hi all, I'm tring to make a script to prompt for a username & then a password for that user onto the actual machine rather than just a web site... now i've come across this this line in some documentation if ( $File = popen( "$useradd_prog $useradd_name", "r" ) ) { . . . now to my actual question .. does that "r" just mean read? and if so should that "r" be a "w" for write in order for it to work? Cheers Peter "the only dumb question is the one that wasn't asked"