Hi ! This is where G-expressions will help you :)
Basically the path you need does not exist in the same "strata" as the code of the package. The following code will define a build-gexp function that evaluates a G-expression and prints the resulting directory in the store. You can try it in "guix repl" or with "guix build -f FILE" https://guix.gnu.org/manual/en/guix.html#G_002dExpressions A G-exp begins with #~ and withing the following expr, any piece of code prefixed by #$ is recursively replaced by its value, but only if this value is a primitive value (string, int,...) or a package. If it is a package, it gets replaced by the path in the store of that package. So to give a short answer, run the following into the REPL to get your path: (use-modules (guix gexp) (guix store) (guix derivations) (gnu packages java)) (define (build-gexp gexp) "Build GEXP using the local daemon." (let ((derivation (run-with-store (open-connection) (gexp->derivation "noname" gexp)))) (build-derivations (open-connection) (list derivation)) (derivation-output-path (assoc-ref (derivation-outputs derivation) "out")))) (build-gexp (with-imported-modules '((guix build utils)) #~(begin (use-modules (guix build utils)) (mkdir-p (string-append #$output "/bin")) (with-output-to-file (string-append #$output "/bin/helloworld.sh") (lambda _ (display (string-append "Iced tea lives at:" #$icedtea-8))))))) This wil output a path, in my case /gnu/store/vv5sc5l488xxysyz88aadjj3fwnqr2xa-noname and in it you'll have the file: /gnu/store/vv5sc5l488xxysyz88aadjj3fwnqr2xa-noname/bin/helloworld.sh which contains Iced tea lives at:/gnu/store/vaqdvsqdv5mads38dp6pc5827pdgnmb3-icedtea-3.7.0 Given your stated use case, you may be interested in the following upcoming patch: https://issues.guix.gnu.org/48277 It will let you wrap any executable in the appropriate env vars, so I guess you will be able to do something like #$(wrap-in-search-paths #~(string-append #$output "/bin/your-script") (list icedtea-8)) Hopefully icedtea-8 sets the correct search paths, but I believe it does. Cheers, Edouard. Phil Beadling writes: > Hi, > > Given a package definition, eg icedtea-8's JDK, how can can I determine the > location of the installed package in my /gnu/store? > > There doesn't seem to be anything on the package module itself, presumably > because this is static data, and what I need is something to calculate the > hash of the resulting install specific to my Guix? > > eg > scheme@(guix-user) [3]> (package-outputs icedtea-8) > $8 = ("out" "jdk" "doc") > scheme@(guix-user) [3]> > > I'd like to return this location using the package name or definition as an > input: > /gnu/store/i3vf1a49m0abcjqza19mb4mkjmc6k60n-icedtea-3.7.0-jdk/ > > The aim is to use this to derivive the JDK include directories in a generic > way for some scripts I'm writing, such that I don't need to update them > each time the JDK hash changes after a guix pull. > > Cheers, > Phil.
