If the program in question can read from stdin, a quick and dirty, although non-portable and non-scalable solution is the following: 
$output = `anotherprogram <<END_OF_DATA\n$lots_of_data\nEND_OF_DATA`;

[download]
In my tests on Linux, it works for up to about 100 KB of data.

In reply to Re: pretending that the contents of a variable are files by itub
in thread pretending that the contents of a variable are files by marcokuma

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