> I call command line tools constantly as the third-party application's API is > not exposed to Perl any other way. >
Sometimes it is unavoidable, sounds like you have done your homework and tried, kudos. > I am wondering why there are at least three options for executing a command > line (including backticks, system() and pipe), if there is a "best" way to > invoke a command line, or what factors are taken into account to determine > which to use. Generally I want the program to wait for the command to > complete (so I think exec() is not an option), and I want the return code, > STDOUT and STDERR from the command (so I don't think system() works for me as > it doesn't give the command's output. > > I would assume that the pipe is most flexible, but I was unable or too lazy to > get it working reliably. If this is the right approach I will give it more time. > Your understanding is right on, there are lots of ways so that you aren't constrained in what you can do. Each can be applied in different situations depending on what *your* needs are. This is one of the reasons why Perl is so great, you are not limited by what the language can accomplish (at least *very* rarely). Your analysis of system and backticks is correct, and it sounds like you want the output, sometimes you won't, in that case go with C<system>. C<system> also allows you to skip shell interpolation of the command line and exec a program directly. A pipe is generally used to talk to the program you are starting, sometimes in uni- but more often in bi- directional communication, in other words, maybe the program is expecting you to give it some info. system/backticks don't provide this (usually). > So I generally use backticks, but what I (sometimes) don't like about this is > that it merges STDOUT and STDERR unless I redirect each to a temp file. Since > sometimes I actually do want the ordered mix, I guess I want one routine that > returns an associative array of everything - OS return code, STDOUT, STDERR, > and merged STDOUT and STDERR, without using temp files. > backticks and system are both very simple, which is why they are nice. In the case that you want the streams separated you might want to consider something like IPC::Open3, For much more information check out, perldoc IPC::Open3 perldoc IPC::Open2 perldoc perlipc perldoc -f system > TIA, > > -John > http://danconia.org -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] <http://learn.perl.org/> <http://learn.perl.org/first-response>
