248 lines
9.8 KiB
Scheme
248 lines
9.8 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2021 Andrew Tropin <andrew@trop.in>
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;;; Copyright © 2021 Xinglu Chen <public@yoctocell.xyz>
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;;;
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;;; This file is part of GNU Guix.
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;;;
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;;; GNU Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Guix is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
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(define-module (gnu home services symlink-manager)
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#:use-module (gnu home services)
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#:use-module (guix gexp)
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#:export (home-symlink-manager-service-type))
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;;; Comment:
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;;;
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;;; symlink-manager cares about configuration files: it backs up files
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;;; created by user, removes symlinks and directories created by a
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;;; previous generation, and creates new directories and symlinks to
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;;; configuration files according to the content of files/ directory
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;;; (created by home-files-service) of the current home environment
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;;; generation.
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;;;
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;;; Code:
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(define (update-symlinks-script)
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(program-file
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"update-symlinks"
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#~(begin
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(use-modules (ice-9 ftw)
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(ice-9 curried-definitions)
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(ice-9 match)
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(srfi srfi-1))
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(define ((simplify-file-tree parent) file)
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"Convert the result produced by `file-system-tree' to less
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verbose and more suitable for further processing format.
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Extract dir/file info from stat and compose a relative path to the
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root of the file tree.
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Sample output:
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((dir . \".\")
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((dir . \"config\")
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((dir . \"config/fontconfig\")
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(file . \"config/fontconfig/fonts.conf\"))
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((dir . \"config/isync\")
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(file . \"config/isync/mbsyncrc\"))))
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"
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(match file
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((name stat) `(file . ,(string-append parent name)))
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((name stat children ...)
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(cons `(dir . ,(string-append parent name))
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(map (simplify-file-tree
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(if (equal? name ".")
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""
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(string-append parent name "/")))
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children)))))
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(define ((file-tree-traverse preordering) node)
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"Traverses the file tree in different orders, depending on PREORDERING.
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if PREORDERING is @code{#t} resulting list will contain directories
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before files located in those directories, otherwise directory will
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appear only after all nested items already listed."
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(let ((prepend (lambda (a b) (append b a))))
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(match node
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(('file . path) (list node))
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((('dir . path) . rest)
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((if preordering append prepend)
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(list (cons 'dir path))
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(append-map (file-tree-traverse preordering) rest))))))
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(use-modules (guix build utils))
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(let* ((config-home (or (getenv "XDG_CONFIG_HOME")
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(string-append (getenv "HOME") "/.config")))
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(he-path (string-append (getenv "HOME") "/.guix-home"))
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(new-he-path (string-append he-path ".new"))
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(new-home (getenv "GUIX_NEW_HOME"))
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(old-home (getenv "GUIX_OLD_HOME"))
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(new-files-path (string-append new-home "/files"))
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;; Trailing dot is required, because files itself is symlink and
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;; to make file-system-tree works it should be a directory.
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(new-files-dir-path (string-append new-files-path "/."))
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(home-path (getenv "HOME"))
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(backup-dir (string-append home-path "/"
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(number->string (current-time))
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"-guix-home-legacy-configs-backup"))
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(old-tree (if old-home
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((simplify-file-tree "")
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(file-system-tree
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(string-append old-home "/files/.")))
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#f))
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(new-tree ((simplify-file-tree "")
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(file-system-tree new-files-dir-path)))
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(get-source-path
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(lambda (path)
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(readlink (string-append new-files-path "/" path))))
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(get-target-path
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(lambda (path)
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(string-append home-path "/." path)))
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(get-backup-path
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(lambda (path)
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(string-append backup-dir "/." path)))
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(directory?
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(lambda (path)
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(equal? (stat:type (stat path)) 'directory)))
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(empty-directory?
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(lambda (dir)
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(equal? (scandir dir) '("." ".."))))
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(symlink-to-store?
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(lambda (path)
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(and
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(equal? (stat:type (lstat path)) 'symlink)
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(store-file-name? (readlink path)))))
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(backup-file
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(lambda (path)
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(mkdir-p backup-dir)
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(format #t "Backing up ~a..." (get-target-path path))
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(mkdir-p (dirname (get-backup-path path)))
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(rename-file (get-target-path path) (get-backup-path path))
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(display " done\n")))
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(cleanup-symlinks
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(lambda ()
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(let ((to-delete ((file-tree-traverse #f) old-tree)))
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(display
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"Cleaning up symlinks from previous home-environment.\n\n")
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(map
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(match-lambda
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(('dir . ".")
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(display "Cleanup finished.\n\n"))
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(('dir . path)
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(if (and
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(file-exists? (get-target-path path))
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(directory? (get-target-path path))
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(empty-directory? (get-target-path path)))
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(begin
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(format #t "Removing ~a..."
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(get-target-path path))
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(rmdir (get-target-path path))
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(display " done\n"))
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(format
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#t "Skipping ~a (not an empty directory)... done\n"
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(get-target-path path))))
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(('file . path)
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(when (file-exists? (get-target-path path))
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;; DO NOT remove the file if it is no longer
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;; a symlink to the store, it will be backed
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;; up later during create-symlinks phase.
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(if (symlink-to-store? (get-target-path path))
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(begin
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(format #t "Removing ~a..." (get-target-path path))
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(delete-file (get-target-path path))
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(display " done\n"))
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(format
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#t
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"Skipping ~a (not a symlink to store)... done\n"
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(get-target-path path))))))
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to-delete))))
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(create-symlinks
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(lambda ()
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(let ((to-create ((file-tree-traverse #t) new-tree)))
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(map
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(match-lambda
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(('dir . ".")
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(display
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"New symlinks to home-environment will be created soon.\n")
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(format
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#t "All conflicting files will go to ~a.\n\n" backup-dir))
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(('dir . path)
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(let ((target-path (get-target-path path)))
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(when (and (file-exists? target-path)
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(not (directory? target-path)))
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(backup-file path))
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(if (file-exists? target-path)
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(format
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#t "Skipping ~a (directory already exists)... done\n"
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target-path)
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(begin
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(format #t "Creating ~a..." target-path)
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(mkdir target-path)
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(display " done\n")))))
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(('file . path)
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(when (file-exists? (get-target-path path))
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(backup-file path))
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(format #t "Symlinking ~a -> ~a..."
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(get-target-path path) (get-source-path path))
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(symlink (get-source-path path) (get-target-path path))
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(display " done\n")))
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to-create)))))
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(when old-tree
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(cleanup-symlinks))
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(create-symlinks)
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(symlink new-home new-he-path)
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(rename-file new-he-path he-path)
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(display " done\nFinished updating symlinks.\n\n")))))
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(define (update-symlinks-gexp _)
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#~(primitive-load #$(update-symlinks-script)))
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(define home-symlink-manager-service-type
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(service-type (name 'home-symlink-manager)
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(extensions
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(list
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(service-extension
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home-activation-service-type
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update-symlinks-gexp)))
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(default-value #f)
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(description "Provide an @code{update-symlinks}
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script, which creates symlinks to configuration files and directories
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on every activation. If an existing file would be overwritten by a
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symlink, backs up that file first.")))
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