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authorEelco Dolstra <e.dolstra@tudelft.nl>2005-02-01T12·36+0000
committerEelco Dolstra <e.dolstra@tudelft.nl>2005-02-01T12·36+0000
commitdcc37c236c66ba463bd61fec23d046485d8a412f (patch)
treeb1a34feaf2a9a0ca0e0bad89c1671289de9e19d2 /src/nix-instantiate/help.txt
parenta6b65fd5e107416588a6572a88518d8816abcb12 (diff)
* nix-store, nix-instantiate: added an option `--add-root' to
  immediately add the result as a permanent GC root.  This is the only
  way to prevent a race with the garbage collector.  For instance, the
  old style

    ln -s $(nix-store -r $(nix-instantiate foo.nix)) \
      /nix/var/nix/gcroots/result

  has two time windows in which the garbage collector can interfere
  (by GC'ing the derivation and the output, respectively).  On the
  other hand,

    nix-store --add-root /nix/var/nix/gcroots/result -r \
      $(nix-instantiate --add-root /nix/var/nix/gcroots/drv \
        foo.nix)

  is safe.

* nix-build: use `--add-root' to prevent GC races.

Diffstat (limited to 'src/nix-instantiate/help.txt')
-rw-r--r--src/nix-instantiate/help.txt4
1 files changed, 3 insertions, 1 deletions
diff --git a/src/nix-instantiate/help.txt b/src/nix-instantiate/help.txt
index 38355ae4a260..5b9d82aa993e 100644
--- a/src/nix-instantiate/help.txt
+++ b/src/nix-instantiate/help.txt
@@ -1,6 +1,6 @@
 nix-instantiate [OPTIONS...] [FILES...]
 
-`nix-instantiate' turns Nix expressions into store expressions. 
+`nix-instantiate' turns Nix expressions into store derivations. 
 
 The argument `-' may be specified to read a Nix expression from
 standard input.
@@ -14,3 +14,5 @@ Options:
 
   --eval-only: evaluate and print resulting term; do not instantiate
   --parse-only: parse and print abstract syntax tree
+
+  --add-root: add garbage collector roots for the result