I hate to say "it depends", but "it depends".

For somethings, you can experiment around with echoing to the command. For example:
system("echo $password | foo -args file");

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Some commands will allow you to put usernames/passwords in files and use those files as input. For example:
system("foo -args file < passwordfile");

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You may also be able to use perl to do some of this echoing. For example:
open(FOO,"| foo -args file");
print FOO "username\n";
print FOO "password\n";
close(FOO);

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You may also want to look into IPC::open2. This allows you to write to a program as well as get information from it.

Finally, you may want to look at the Expect module. This allows you to wait on a particular prompt to which you can respond.

Hopefully, one of the solutions above (or a combination thereof) will help you out. Good luck.

Hope that helps,
Shendal

Update: The above is meant as quick example only. You will, of course, want to do some checking on your system calls before launching any programs, as KM points out in his well-crafted example below.

In reply to Re: passwords and system calls by Shendal
in thread passwords and system calls by Anonymous Monk

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