Is scheme a suitable replacement for perl or ruby for everyday small-scale programming?
Racket has a minor language for shell mix-ins[1] and Racket itself has some nice ways of dealing with command-line arguments[2]. However, all command-line arguments are passed as strings, which means extra steps in converting them to native types (numbers etc.). I find it very pleasant and Racket in particular has both a good standard library and a whole bunch of libraries that probably cover a majority of what one might need for smaller tasks. But again, it depends on what you consider "small-scale programming"
[1]: http://docs.racket-lang.org/rash/index.html
[2]: http://docs.racket-lang.org/reference/Command-Line_Parsing.h...
Racket is not just Scheme anymore, but it does still support various versions of Scheme as well as a number of Scheme-based languages. It has a package management system and a fairly large set of packages for basic tasks. The core system, base libraries, and major libraries are well documented and it's got a great built-in IDE.
Guile also does more than just Scheme, but it's been the "official extension language of GNU" for a very long time, so it's got bindings to a lot of libraries and it's used in some interesting applications and tools.
Chicken Scheme also comes with a package system, 'eggs', that has a pretty nice collection of practical packages available for easy installation. You can run your programs via the interpreter, or you can compile them via the compiler, which goes through C so it's got great C interop.
There are a lot of other options with a variety of strengths and weaknesses, but those are good ones to look at for starting out and doing scripting duties.
Personally, I use Chicken Scheme for command-line utils (thanks to AOT compilation Chicken Scheme programs start-up time is much shorter) and Racket for GUI programs. Both implementations offer stability, ongoing development and a package ecosystem which has most of the things I need. They also provide extensive tooling, with Racket going as far as providing an IDE and visual debugger.
Most of the problems you'd have when replacing PERL or Ruby with a Scheme would have to do with library/package availability. If your use-case doesn't require a library which your Scheme lacks it may be a suitable replacement for PERL, Ruby, Python or JavaScript (node).
Scheme and CL bicker over whether an empty list embodies the concept of falsehood. JavaScript says wat? And Haskell is like, lol.
Then here are some very nice SRFIs around to do most of what you want, and I believe chicken comes with basic pattern matching facilities as well (although not as sweet as the ML-type which are checked at compile time).