Hi,

I changed 'roll-back', but didn't add the command-line option.  Could
you add it?

Why do these lines raise the "non-literal format string" warning?

+        (format (current-error-port)
+                "error: '~a' is not a valid profile~%"
+                profile)

Also, is it possible to remove nested if statements?

+    (if (= number 0)
+        (format (current-error-port)
+                "error: '~a' is not a valid profile~%"
+                profile)
+        (if (file-exists? previous-profile)
+            (switch-link)
+            (format (current-error-port)
+                    (string-append "error: previous profile doesn't exist; "
+                                   "not rolling back~%"))))))

> I think it works even if PROFILE is not an absolute file name, no?

Maybe I misunderstood, but the following doesn't work.

scheme@(guile-user)> (define %current-profile "/nix/var/nix/profiles/per-user/root/guix-profile")
scheme@(guile-user)> (profile-number %current-profile)
$1 = 1
scheme@(guile-user)> (profile-number (basename %current-profile))
$2 = 0

Nikita