* Improvements to profiles. Generations are now per-profile, e.g.,

  default -> default-94-link
  default-82-link -> /nix/store/cc4480...
  default-83-link -> /nix/store/caeec8...
  ...
  default-94-link -> /nix/store/2896ca...
  experimental -> experimental-2-link
  experimental-1-link -> /nix/store/cc4480...
  experimental-2-link -> /nix/store/a3148f...

* `--profile' / `-p' -> `--switch-profile' / `-S'
* `--link' / `-l' -> `--profile' / `-p'
* The default profile is stored in $prefix/var/nix/profiles.
  $prefix/var/nix/links is gone.  Profiles can be stored anywhere.
* The current profile is now referenced from ~/.nix-profile, not
  ~/.nix-userenv.
* The roots to the garbage collector now have extension `.gcroot', not
  `.id'.

doc/manual/installation.xml

@@ -192,9 +192,9 @@ rm -rf /nix/var</screen>
       To use Nix, some environment variables should be set.  In
       particular, <envar>PATH</envar> should contain the directories
       <filename><replaceable>prefix</replaceable>/bin</filename> and
-      <filename>~/.nix-userenv/bin</filename>.  The first directory
+      <filename>~/.nix-profile/bin</filename>.  The first directory
       contains the Nix tools themselves, while
-      <filename>~/.nix-userenv</filename> is a symbolic link to the
+      <filename>~/.nix-profile</filename> is a symbolic link to the
       current <emphasis>user environment</emphasis> (an automatically
       generated package consisting of symlinks to installed packages).
       The simplest way to set the required environment variables is to

doc/manual/nix-env.xml

@@ -111,14 +111,14 @@
       </varlistentry>
 
       <varlistentry>
-        <term><filename>~/.nix-userenv</filename></term>
+        <term><filename>~/.nix-profile</filename></term>
         <listitem>
           <para>
-            A symbolic link to the user's current user environment.
-            By default, it points to
-            <filename><replaceable>prefix</replaceable>/var/nix/links/current</filename>.
+            A symbolic link to the user's current profile.  The
+            default profile is
+            <filename><replaceable>prefix</replaceable>/var/nix/profiles/default</filename>.
             The <envar>PATH</envar> environment variable should
-            include <filename>~/.nix-userenv</filename> for the user
+            include <filename>~/.nix-profile/bin</filename> for the user
             environment to be visible to the user.
           </para>
         </listitem>

doc/manual/overview.xml

@@ -189,30 +189,32 @@ obtaining list of Nix archives at http://catamaran.labs.cs.uu.nl/dist/nix/nixpkg
       it can be used immediately, that is, it now appears in a directory in the
       <envar>PATH</envar> environment variable.  Specifically,
       <envar>PATH</envar> includes the entry
-      <filename><replaceable>prefix</replaceable>/var/nix/links/current/bin</filename>, 
+      <filename><replaceable>prefix</replaceable>/var/nix/profiles/default/bin</filename>, 
       where
-      <filename><replaceable>prefix</replaceable>/var/nix/links/current</filename> 
+      <filename><replaceable>prefix</replaceable>/var/nix/profiles/default</filename> 
       is just a symlink to the current user environment:
     </para>
 
     <screen>
-$ ls -l /nix/var/nix/links/
+$ ls -l /nix/var/nix/profiles/
 ...
-lrwxrwxrwx  1 eelco ... 15 -> /nix/store/1871...12b0-user-environment
-lrwxrwxrwx  1 eelco ... 16 -> /nix/store/59ba...df6b-user-environment
-lrwxrwxrwx  1 eelco ... current -> /nix/var/nix/links/16</screen>
+lrwxrwxrwx  1 eelco ... default-15-link -> /nix/store/1871...12b0-user-environment
+lrwxrwxrwx  1 eelco ... default-16-link -> /nix/store/59ba...df6b-user-environment
+lrwxrwxrwx  1 eelco ... default -> default-16-link</screen>
 
     <para>
-      That is, <filename>current</filename> in this example is a link to
-      <filename>16</filename>, which is the current user environment.  Before
-      the installation, it pointed to <filename>15</filename>.  Note that this
-      means that you can atomically roll-back to the previous user environment
-      by pointing the symlink <filename>current</filename> at
-      <filename>15</filename> again.  This also shows that operations such as
-      installation are atomic in the Nix system: any arbitrarily complex
-      set of installation, uninstallation, or upgrade actions eventually boil
-      down to the single operation of pointing a symlink somewhere else (which
-      can be implemented atomically in Unix).
+      That is, <filename>default</filename> in this example is a link
+      to <filename>default-16-link</filename>, which is the current
+      user environment.  Before the installation, it pointed to
+      <filename>default-15-link</filename>.  Note that this means that
+      you can atomically roll-back to the previous user environment by
+      pointing the symlink <filename>default</filename> at
+      <filename>default-15-link</filename> again.  This also shows
+      that operations such as installation are atomic in the Nix
+      system: any arbitrarily complex set of installation,
+      uninstallation, or upgrade actions eventually boil down to the
+      single operation of pointing a symlink somewhere else (which can
+      be implemented atomically in Unix).
     </para>
 
     <para>
@@ -221,15 +223,15 @@ lrwxrwxrwx  1 eelco ... current -> /nix/var/nix/links/16</screen>
     </para>
 
     <screen>
-$ ls -l /nix/var/nix/links/16/bin
+$ ls -l /nix/var/nix/profiles/default-16-link/bin
 lrwxrwxrwx  1 eelco ... MozillaFirebird -> /nix/store/35f8...4ae6-MozillaFirebird-0.7/bin/MozillaFirebird
 lrwxrwxrwx  1 eelco ... svn -> /nix/store/3829...fb5d-subversion-0.32.1/bin/svn
 ...</screen>
 
     <para>
       Note that, e.g., <filename>svn</filename> =
-      <filename>/nix/var/nix/links/current/bin/svn</filename> =
-      <filename>/nix/var/nix/links/16/bin/svn</filename> =
+      <filename>/nix/var/nix/profiles/default/bin/svn</filename> =
+      <filename>/nix/var/nix/profiles/default-16-link/bin/svn</filename> =
       <filename>/nix/store/59ba...df6b-user-environment/bin/svn</filename> =
       <filename>/nix/store/3829...fb5d-subversion-0.32.1/bin/svn</filename>.
     </para>

doc/manual/quick-start.xml

@@ -93,7 +93,7 @@ $ nix-env -iBf nixpkgs-<replaceable>version</replaceable>/ hello MozillaFirebird
 
         <screen>
 $ which hello
-/home/eelco/.nix-userenv/bin/hello
+/home/eelco/.nix-profile/bin/hello
 $ hello
 Hello, world!
 $ MozillaFirebird

scripts/nix-collect-garbage.in

@@ -3,7 +3,7 @@
 use strict;
 use IPC::Open2;
 
-my $linkdir = "@localstatedir@/nix/links";
+my $linkdir = "@localstatedir@/nix/profiles";
 my $storedir = "@prefix@/store";
 
 my %alive;
@@ -24,7 +24,7 @@ closedir DIR;
 my @roots;
 foreach my $link (@links) {
     $link = $linkdir . "/" . $link;
-    next if (!($link =~ /.id$/));
+    next if (!($link =~ /.gcroot$/));
     open ROOT, "<$link" or die "cannot open $link: $!";
     my $root = <ROOT>;
     chomp $root;

scripts/nix-profile.sh.in

 if test -n "$HOME"; then
-    NIX_LINK="$HOME/.nix-userenv"
+    NIX_LINK="$HOME/.nix-profile"
 
     if ! test -L "$NIX_LINK"; then
         echo "creating $NIX_LINK"
-        _NIX_DEF_LINK=@localstatedir@/nix/links/current
+        _NIX_DEF_LINK=@localstatedir@/nix/profiles/default
         ln -s "$_NIX_DEF_LINK" "$NIX_LINK"
     fi
 

src/nix-env/Makefile.am

@@ -14,3 +14,6 @@ main.o: help.txt.hh
 AM_CXXFLAGS = \
  -I.. -I../../externals/inst/include -I../libutil -I../libstore \
  -I../libexpr -I../libmain
+
+install-data-local:
+	$(INSTALL) -d $(DESTDIR)$(localstatedir)/nix/profiles

src/nix-env/help.txt

@@ -12,7 +12,7 @@ Operations:
 The previous operations take a list of derivation names.  The special
 name `*' may be used to indicate all derivations.
 
-  --profile / -p [FILE]: switch to specified user environment
+  --switch-profile / -S [FILE]: switch to specified profile
   --import / -I FILE: set default Nix expression
 
   --version: output version information
@@ -31,7 +31,7 @@ Query sources:
 
 Options:
 
-  --link / -l LINK: use symlink LINK instead of (...)/current
+  --profile / -p LINK: use specified profile instead of target of ~/.nix-profile
   --file / -f FILE: use Nix expression FILE for installation, etc.
   --verbose / -v: verbose operation (may be repeated)
   --keep-failed / -K: keep temporary directories of failed builds

src/nix-env/main.cc

@@ -10,7 +10,7 @@
 
 struct Globals
 {
-    Path linkPath;
+    Path profile;
     Path nixExprPath;
     EvalState state;
 };
@@ -116,12 +116,6 @@ static Path getHomeDir()
 }
 
 
-static Path getLinksDir()
-{
-    return canonPath(nixStateDir + "/links");
-}
-
-
 static Path getDefNixExprPath()
 {
     return getHomeDir() + "/.nix-defexpr";
@@ -143,23 +137,30 @@ void queryInstalled(EvalState & state, DrvInfos & drvs,
 }
 
 
-Path createGeneration(Path outPath, Path drvPath)
+Path createGeneration(Path profile, Path outPath, Path drvPath)
 {
-    Path linksDir = getLinksDir();
-
+    Path profileDir = dirOf(profile);
+    string profileName = baseNameOf(profile);
+    
     unsigned int num = 0;
     
-    Strings names = readDirectory(linksDir);
+    Strings names = readDirectory(profileDir);
     for (Strings::iterator i = names.begin(); i != names.end(); ++i) {
-        istringstream s(*i);
-        unsigned int n; 
-        if (s >> n && s.eof() && n >= num) num = n + 1;
+        if (string(*i, 0, profileName.size() + 1) != profileName + "-") continue;
+        string s = string(*i, profileName.size() + 1);
+        int p = s.find("-link");
+        if (p == string::npos) continue;
+        istringstream str(string(s, 0, p));
+        unsigned int n;
+        if (str >> n && str.eof() && n >= num) num = n + 1;
     }
 
-    Path generation;
+    Path generation, gcrootSrc;
 
     while (1) {
-        generation = (format("%1%/%2%") % linksDir % num).str();
+        Path prefix = (format("%1%-%2%") % profile % num).str();
+        generation = prefix + "-link";
+        gcrootSrc = prefix + "-src.gcroot";
         if (symlink(outPath.c_str(), generation.c_str()) == 0) break;
         if (errno != EEXIST)
             throw SysError(format("creating symlink `%1%'") % generation);
@@ -167,7 +168,7 @@ Path createGeneration(Path outPath, Path drvPath)
         num++;
     }
 
-    writeStringToFile(generation + "-src.id", drvPath);
+    writeStringToFile(gcrootSrc, drvPath);
 
     return generation;
 }
@@ -175,6 +176,9 @@ Path createGeneration(Path outPath, Path drvPath)
 
 void switchLink(Path link, Path target)
 {
+    /* Hacky. */
+    if (dirOf(target) == dirOf(link)) target = baseNameOf(target);
+    
     Path tmp = canonPath(dirOf(link) + "/.new_" + baseNameOf(link));
     if (symlink(target.c_str(), tmp.c_str()) != 0)
         throw SysError(format("creating symlink `%1%'") % tmp);
@@ -190,7 +194,7 @@ void switchLink(Path link, Path target)
 
 
 void createUserEnv(EvalState & state, const DrvInfos & drvs,
-    const Path & linkPath)
+    const Path & profile)
 {
     /* Get the environment builder expression. */
     Expr envBuilder = parseExprFromFile(state,
@@ -243,9 +247,9 @@ void createUserEnv(EvalState & state, const DrvInfos & drvs,
 
     /* Switch the current user environment to the output path. */
     debug(format("switching to new user environment"));
-    Path generation = createGeneration(
+    Path generation = createGeneration(profile,
         topLevelDrv.outPath, topLevelDrv.drvPath);
-    switchLink(linkPath, generation);
+    switchLink(profile, generation);
 }
 
 
@@ -380,7 +384,7 @@ static DrvNames drvNamesFromArgs(const Strings & opArgs)
 
 
 static void installDerivations(EvalState & state,
-    Path nePath, DrvNames & selectors, const Path & linkPath)
+    Path nePath, DrvNames & selectors, const Path & profile)
 {
     debug(format("installing derivations from `%1%'") % nePath);
 
@@ -415,10 +419,10 @@ static void installDerivations(EvalState & state,
     
     /* Add in the already installed derivations. */
     DrvInfos installedDrvs;
-    queryInstalled(state, installedDrvs, linkPath);
+    queryInstalled(state, installedDrvs, profile);
     selectedDrvs.insert(installedDrvs.begin(), installedDrvs.end());
 
-    createUserEnv(state, selectedDrvs, linkPath);
+    createUserEnv(state, selectedDrvs, profile);
 }
 
 
@@ -431,12 +435,12 @@ static void opInstall(Globals & globals,
     DrvNames drvNames = drvNamesFromArgs(opArgs);
     
     installDerivations(globals.state, globals.nixExprPath,
-        drvNames, globals.linkPath);
+        drvNames, globals.profile);
 }
 
 
 static void upgradeDerivations(EvalState & state,
-    Path nePath, DrvNames & selectors, const Path & linkPath)
+    Path nePath, DrvNames & selectors, const Path & profile)
 {
     debug(format("upgrading derivations from `%1%'") % nePath);
 
@@ -447,7 +451,7 @@ static void upgradeDerivations(EvalState & state,
 
     /* Load the currently installed derivations. */
     DrvInfos installedDrvs;
-    queryInstalled(state, installedDrvs, linkPath);
+    queryInstalled(state, installedDrvs, profile);
 
     /* Fetch all derivations from the input file. */
     DrvInfos availDrvs;
@@ -496,7 +500,7 @@ static void upgradeDerivations(EvalState & state,
         newDrvs.insert(*bestDrv);
     }
     
-    createUserEnv(state, newDrvs, linkPath);
+    createUserEnv(state, newDrvs, profile);
 }
 
 
@@ -510,15 +514,15 @@ static void opUpgrade(Globals & globals,
     DrvNames drvNames = drvNamesFromArgs(opArgs);
     
     upgradeDerivations(globals.state, globals.nixExprPath,
-        drvNames, globals.linkPath);
+        drvNames, globals.profile);
 }
 
 
 static void uninstallDerivations(EvalState & state, DrvNames & selectors,
-    Path & linkPath)
+    Path & profile)
 {
     DrvInfos installedDrvs;
-    queryInstalled(state, installedDrvs, linkPath);
+    queryInstalled(state, installedDrvs, profile);
 
     for (DrvInfos::iterator i = installedDrvs.begin();
          i != installedDrvs.end(); ++i)
@@ -533,7 +537,7 @@ static void uninstallDerivations(EvalState & state, DrvNames & selectors,
             }
     }
 
-    createUserEnv(state, installedDrvs, linkPath);
+    createUserEnv(state, installedDrvs, profile);
 }
 
 
@@ -545,7 +549,7 @@ static void opUninstall(Globals & globals,
 
     DrvNames drvNames = drvNamesFromArgs(opArgs);
 
-    uninstallDerivations(globals.state, drvNames, globals.linkPath);
+    uninstallDerivations(globals.state, drvNames, globals.profile);
 }
 
 
@@ -576,7 +580,7 @@ static void opQuery(Globals & globals,
     switch (source) {
 
         case sInstalled:
-            queryInstalled(globals.state, drvs, globals.linkPath);
+            queryInstalled(globals.state, drvs, globals.profile);
             break;
 
         case sAvailable: {
@@ -612,7 +616,7 @@ static void opQuery(Globals & globals,
         
         case qStatus: {
             DrvInfos installed;
-            queryInstalled(globals.state, installed, globals.linkPath);
+            queryInstalled(globals.state, installed, globals.profile);
 
             PathSet installedPaths; /* output paths of installed drvs */
             for (DrvInfos::iterator i = installed.begin();
@@ -644,11 +648,11 @@ static void opSwitchProfile(Globals & globals,
     if (opArgs.size() > 1)
         throw UsageError(format("`--profile' takes at most one argument"));
 
-    Path linkPath = 
-        absPath(opArgs.size() == 0 ? globals.linkPath : opArgs.front());
-    Path linkPathFinal = getHomeDir() + "/.nix-userenv";
+    Path profile = 
+        absPath(opArgs.size() == 0 ? globals.profile : opArgs.front());
+    Path profileLink = getHomeDir() + "/.nix-userenv";
 
-    switchLink(linkPathFinal, linkPath);
+    switchLink(profileLink, profile);
 }
 
 
@@ -676,7 +680,7 @@ void run(Strings args)
     Operation op = 0;
     
     Globals globals;
-    globals.linkPath = getLinksDir() + "/current";
+    globals.profile = canonPath(nixStateDir + "/profiles/default");
     globals.nixExprPath = getDefNixExprPath();
 
     for (Strings::iterator i = args.begin(); i != args.end(); ++i) {
@@ -694,11 +698,11 @@ void run(Strings args)
             op = opQuery;
         else if (arg == "--import" || arg == "-I") /* !!! bad name */
             op = opDefaultExpr;
-        else if (arg == "--link" || arg == "-l") {
+        else if (arg == "--profile" || arg == "-p") {
             ++i;
             if (i == args.end()) throw UsageError(
                 format("`%1%' requires an argument") % arg);
-            globals.linkPath = absPath(*i);
+            globals.profile = absPath(*i);
         }
         else if (arg == "--file" || arg == "-f") {
             ++i;
@@ -706,7 +710,7 @@ void run(Strings args)
                 format("`%1%' requires an argument") % arg);
             globals.nixExprPath = absPath(*i);
         }
-        else if (arg == "--profile" || arg == "-p") 
+        else if (arg == "--switch-profile" || arg == "-S")
             op = opSwitchProfile;
         else if (arg[0] == '-')
             opFlags.push_back(arg);

src/nix-store/Makefile.am

@@ -15,9 +15,6 @@ AM_CXXFLAGS = \
 install-data-local:
 	$(INSTALL) -d $(DESTDIR)$(localstatedir)/nix
 	$(INSTALL) -d $(DESTDIR)$(localstatedir)/nix/db
-	$(INSTALL) -d $(DESTDIR)$(localstatedir)/nix/links
-	rm -f $(DESTDIR)$(prefix)/current
-	ln -sf $(localstatedir)/nix/links/current $(DESTDIR)$(prefix)/current
 	$(INSTALL) -d $(DESTDIR)$(localstatedir)/log/nix
 	$(INSTALL) -d $(DESTDIR)$(prefix)/store
 #	$(bindir)/nix-store --init