* `nix-env --upgrade --eq': only upgrade if the old version is equal

  to the new version.  This is actually useful.

2 files changed, 5 insertions, 2 deletions

diff --git a/src/nix-env/help.txt b/src/nix-env/help.txt
index d20c366cb7bf..e8319477415f 100644
--- a/src/nix-env/help.txt
+++ b/src/nix-env/help.txt
@@ -31,7 +31,8 @@ Install / upgrade / uninstall flags:
 Upgrade flags:
 
   --lt: upgrade if the current version is older (default)
-  --leq: upgrade if the current version is older or current
+  --leq: upgrade if the current version is older or equal
+  --eq: "upgrade" if the current version is equal
   --always: upgrade regardless of current version
 
 Query types:
diff --git a/src/nix-env/main.cc b/src/nix-env/main.cc
index 0198aed575c9..400bb0d87734 100644
--- a/src/nix-env/main.cc
+++ b/src/nix-env/main.cc
@@ -476,7 +476,7 @@ static void opInstall(Globals & globals,
 }
 
 
-typedef enum { utLt, utLeq, utAlways } UpgradeType;
+typedef enum { utLt, utLeq, utEq, utAlways } UpgradeType;
 
 
 static void upgradeDerivations(Globals & globals,
@@ -520,6 +520,7 @@ static void upgradeDerivations(Globals & globals,
                 int d = compareVersions(drvName.version, newName.version);
                 if (upgradeType == utLt && d < 0 ||
                     upgradeType == utLeq && d <= 0 ||
+                    upgradeType == utEq && d == 0 ||
                     upgradeType == utAlways)
                 {
                     if ((bestElem == availElems.end() ||
@@ -562,6 +563,7 @@ static void opUpgrade(Globals & globals,
          i != opFlags.end(); ++i)
         if (*i == "--lt") upgradeType = utLt;
         else if (*i == "--leq") upgradeType = utLeq;
+        else if (*i == "--eq") upgradeType = utEq;
         else if (*i == "--always") upgradeType = utAlways;
         else throw UsageError(format("unknown flag `%1%'") % *i);