utils: Add `which'.

* guix/build/utils.scm (which): New procedure.

* distro/packages/lsh.scm (lsh): Use `which' instead of `search-path'.
* distro/packages/perl.scm (perl): Likewise.
* distro/packages/attr.scm (attr): Likewise.

distro/packages/attr.scm

@@ -56,12 +56,9 @@
           'check
           (lambda _
             ;; Use the right shell.
-            (let ((bash (search-path (search-path-as-string->list
-                                      (getenv "PATH"))
-                                     "bash")))
-              (substitute* "test/run"
-                (("/bin/sh")
-                 (string-append bash "/bin/bash"))))
+            (substitute* "test/run"
+              (("/bin/sh")
+               (which "bash")))
 
             (system* "make" "tests" "-C" "test")
 

distro/packages/lsh.scm

@@ -1,5 +1,5 @@
 ;;; Guix --- Nix package management from Guile.         -*- coding: utf-8 -*-
-;;; Copyright (C) 2012 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright (C) 2012, 2013 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of Guix.
 ;;;
@@ -114,8 +114,7 @@
           (substitute* "src/testsuite/login-auth-test"
             (("/bin/cat")
              ;; Use the right path to `cat'.
-             (search-path (search-path-as-string->list (getenv "PATH"))
-                          "cat"))))
+             (which "cat"))))
         %standard-phases)))
     (home-page "http://www.lysator.liu.se/~nisse/lsh/")
     (synopsis

distro/packages/perl.scm

@@ -1,5 +1,5 @@
 ;;; Guix --- Nix package management from Guile.         -*- coding: utf-8 -*-
-;;; Copyright (C) 2012 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright (C) 2012, 2013 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of Guix.
 ;;;
@@ -46,13 +46,11 @@
           'configure
           (lambda* (#:key inputs outputs #:allow-other-keys)
             (let ((out  (assoc-ref outputs "out"))
-                  (libc (assoc-ref inputs "libc"))
-                  (pwd  (search-path (search-path-as-string->list
-                                      (getenv "PATH"))
-                                     "pwd")))
+                  (libc (assoc-ref inputs "libc")))
               ;; Use the right path for `pwd'.
               (substitute* "dist/Cwd/Cwd.pm"
-                (("/bin/pwd") pwd))
+                (("/bin/pwd")
+                 (which "pwd")))
 
               (zero?
                (system* "./Configure"

guix/build/utils.scm

@@ -36,6 +36,8 @@
             set-path-environment-variable
             search-path-as-string->list
             list->search-path-as-string
+            which
+
             alist-cons-before
             alist-cons-after
             alist-replace
@@ -214,6 +216,12 @@ SEPARATOR-separated path accordingly.  Example:
    (format #t "environment variable `~a' set to `~a'~%"
            env-var value)))
 
+(define (which program)
+  "Return the complete file name for PROGRAM as found in $PATH, or #f if
+PROGRAM could not be found."
+  (search-path (search-path-as-string->list (getenv "PATH"))
+               program))
+
 
 ;;;
 ;;; Phases.