gnu: xmlstarlet: Install symlink to xmlstarlet binary.

* gnu/packages/xml.scm (xmlstarlet)[arguments]: Add 'symlink-xmlstarlet
phase.

gnu/packages/xml.scm

@@ -25,6 +25,7 @@
 ;;; Copyright © 2020 Paul Garlick <pgarlick@tourbillion-technology.com>
 ;;; Copyright © 2020 Edouard Klein <edk@beaver-labs.com>
 ;;; Copyright © 2020 Brett Gilio <brettg@gnu.org>
+;;; Copyright © 2020 Pierre Langlois <pierre.langlois@gmx.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -1260,7 +1261,15 @@ C++ programming language.")
            (substitute* "Makefile"
              (("^examples/schema1\\\\") "\\")
              (("^examples/valid1\\\\") "\\"))
-           #t)))))
+           #t))
+       (add-after 'install 'symlink-xmlstarlet
+         (lambda* (#:key outputs #:allow-other-keys)
+           ;; Other distros usually either rename or symlink the `xml' binary
+           ;; as `xmlstarlet', let's do it as well for compatibility.
+           (let* ((out (assoc-ref outputs "out"))
+                  (bin (string-append out "/bin")))
+             (symlink "xml" (string-append bin "/xmlstarlet"))
+             #t))))))
    (inputs
     `(("libxslt" ,libxslt)
       ("libxml2" ,libxml2)))