B<mr> [options] log
 
+B<mr> [options] register [repository]
+
+B<mr> [options] config section [parameter=[value] ...]
+
 B<mr> [options] action [params ...]
 
 =head1 DESCRIPTION
 
 List the repositories that mr will act on.
 
+=item register
+
+Register an existing repository in the mrconfig file. By default, the
+epository in the current directory is registered, or you can specify a
+directory to register.
+
+=item config
+
+Adds, modifies, removes, or prints a value from the mrconfig file. The next
+parameter is the name of the section the value is in. To add or modify
+values, use one or more instances of "parameter=value". Use "parameter=" to
+remove a parameter. Use just "parameter" to get the value of a parameter.
+
+For example, to add (or edit) a repository in src/foo:
+
+  mr config src/foo checkout="svn co svn://example.com/foo/trunk foo"
+
+To show the command that mr uses to update the repository in src/foo:
+
+  mr config src/foo update
+
 =item help
 
 Displays this help.
 "mr st" is equivilant to "mr status", and "mr up" is equivilant to "mr
 update"
 
-Additional parameters can be passed to other commands than "commit", they
-will be passed on unchanged to the underlying revision control system.
-This is mostly useful if the repositories mr will act on all use the same
-revision control system.
+Additional parameters can be passed to most commands, and are passed on
+unchanged to the underlying revision control system. This is mostly useful
+if the repositories mr will act on all use the same revision control
+system.
 
 =head1 OPTIONS
 
 The .mrconfig file uses a variant of the INI file format. Lines starting with
 "#" are comments. Lines ending with "\" are continued on to the next line.
 
-The "default" section allows setting default values for the sections that
+The "DEFAULT" section allows setting default values for the sections that
 come after it.
 
-The "alias" section allows adding aliases for actions. Each parameter
+The "ALIAS" section allows adding aliases for actions. Each parameter
 is an alias, and its value is the action to use.
 
-All other sections specify where each repository is located, relative to the
-directory that contains the .mrconfig file.
+All other sections add repositories. The section header specifies the
+directory where the repository is located. This is relative to the directory
+that contains the mrconfig file, but you can also choose to use absolute
+paths.
 
 Within a section, each parameter defines a shell command to run to handle a
 given action. mr contains default handlers for the "update", "status", and
 =item skip
 
 If the "skip" parameter is set and its command returns nonzero, then B<mr>
-will skip acting on that repository.
+will skip acting on that repository. The command is passed the action
+name in $1.
+
+Here are two examples. The first skips the repo unless
+mr is run by joey. The second uses the hours_since function
+(included in mr's built-in library) to skip updating the repo unless it's
+been at least 12 hours since the last update.
+
+  skip = test $(whoami) != joey
+  skip = [ "$1" = update ] && [ $(hours_since "$1") -lt 12 ]
 
 =item chain
 
 will try to load a .mrconfig file from the root of the repository. (You
 should avoid chaining from repositories with untrusted committers.)
 
+=item deleted
+
+If the "deleted" parameter is set and its command returns nonzero, then
+B<mr> will treat the repository as deleted. It won't ever actually delete
+the repository, but it will warn if it sees the repsoitory's directory.
+This is useful when one mrconfig file is shared amoung multiple machines,
+to keep track of and remember to delete old repositories.
+
 =item lib
 
 The "lib" parameter can specify some shell code that will be run before each
 }
 
 if ($action eq 'help') {
-       exec($config{''}{default}{help});
+       exec($config{''}{DEFAULT}{$action}) || die "exec: $!";
+}
+elsif ($action eq 'config') {
+       if (@ARGV < 2) {
+               die "mr config: not enough parameters\n";
+       }
+       my $section=shift;
+       if ($section=~/^\//) {
+               # try to convert to a path relative to $config's dir
+               my ($dir)=$config=~/^(.*\/)[^\/]+$/;
+               if ($section=~/^\Q$dir\E(.*)/) {
+                       $section=$1;
+               }
+       }
+       my %changefields;
+       foreach (@ARGV) {
+               if (/^([^=]+)=(.*)$/) {
+                       $changefields{$1}=$2;
+               }
+               else {
+                       my $found=0;
+                       foreach my $topdir (sort keys %config) {
+                               if (exists $config{$topdir}{$section} &&
+                                   exists $config{$topdir}{$section}{$_}) {
+                                       print $config{$topdir}{$section}{$_}."\n";
+                                       $found=1;
+                               }
+                       }
+                       if (! $found) {
+                               die "mr $action: $section $_ not set\n";
+                       }
+               }
+       }
+       modifyconfig($config, $section, %changefields) if %changefields;
+       exit 0;
+}
+elsif ($action eq 'register') {
+       my $command="set -e; ".$config{''}{DEFAULT}{lib}."\n".
+               "my_action(){ $config{''}{DEFAULT}{$action}\n }; my_action ".
+               join(" ", map { s/\//\/\//g; s/"/\"/g; '"'.$_.'"' } @ARGV);
+       print STDERR "mr $action: running >>$command<<\n" if $verbose;
+       exec($command) || die "exec: $!";
 }
 
 # work out what repos to act on
 my $nochdir=0;
 foreach my $topdir (sort keys %config) {
        foreach my $subdir (sort keys %{$config{$topdir}}) {
-               next if $subdir eq 'default';
-               my $dir=$topdir.$subdir;
-               next if $dir ne $directory && $dir !~ /^\Q$directory\E\//;
+               next if $subdir eq 'DEFAULT';
+               my $dir=($subdir =~/^\//) ? $subdir : $topdir.$subdir;
+               my $d=$directory;
+               $dir.="/" unless $dir=~/\/$/;
+               $d.="/" unless $d=~/\/$/;
+               next if $dir ne $directory && $dir !~ /^\Q$directory\E/;
                push @repos, [$dir, $topdir, $subdir];
        }
 }
        # fallback to find a leaf repo
        LEAF: foreach my $topdir (reverse sort keys %config) {
                foreach my $subdir (reverse sort keys %{$config{$topdir}}) {
-                       next if $subdir eq 'default';
-                       my $dir=$topdir.$subdir;
+                       next if $subdir eq 'DEFAULT';
+                       my $dir=($subdir =~/^\//) ? $subdir : $topdir.$subdir;
                        my $d=$directory;
                        $dir.="/" unless $dir=~/\/$/;
                        $d.="/" unless $d=~/\/$/;
        my ($action, $dir, $topdir, $subdir) = @_;
        
        my $lib= exists $config{$topdir}{$subdir}{lib} ?
-                       $config{$topdir}{$subdir}{lib} : "";
+                       $config{$topdir}{$subdir}{lib}."\n" : "";
+
+       if (exists $config{$topdir}{$subdir}{deleted}) {
+               if (! -d $dir) {
+                       return;
+               }
+               else {
+                       my $test="set -e;".$lib.$config{$topdir}{$subdir}{deleted};
+                       print "mr $action: running deleted test >>$test<<\n" if $verbose;
+                       my $ret=system($test);
+                       if ($ret >> 8 == 0) {
+                               print STDERR "mr error: $dir should be deleted yet still exists\n\n";
+                               push @failed, $dir;
+                               return;
+                       }
+               }
+       }
 
        if ($action eq 'checkout') {
                if (-d $dir) {
        $ENV{MR_REPO}=$dir;
 
        if (exists $config{$topdir}{$subdir}{skip}) {
-               my $test="set -e;".$lib.$config{$topdir}{$subdir}{skip};
-               print "mr $action: running skip test $test\n" if $verbose;
+               my $test="set -e;".$lib.
+                       "my_action(){ $config{$topdir}{$subdir}{skip}\n }; my_action '$action'";
+               print "mr $action: running skip test >>$test<<\n" if $verbose;
                my $ret=system($test);
                if ($ret >> 8 == 0) {
                        print "mr $action: $dir skipped per config file\n" if $verbose;
        }
        else {
                if (! $nochdir) {
-                       print "mr $action: $dir\n";
+                       print "mr $action: $topdir$subdir\n";
                }
                else {
-                       print "mr $action: $dir (in subdir $directory)\n";
+                       print "mr $action: $topdir$subdir (in subdir $directory)\n";
                }
                my $command="set -e; ".$lib.
-                       "my_action(){ $config{$topdir}{$subdir}{$action} ; }; my_action ".
+                       "my_action(){ $config{$topdir}{$subdir}{$action}\n }; my_action ".
                        join(" ", map { s/\//\/\//g; s/"/\"/g; '"'.$_.'"' } @ARGV);
-               print STDERR "mr $action: running $command\n" if $verbose;
+               print STDERR "mr $action: running >>$command<<\n" if $verbose;
                my $ret=system($command);
                if ($ret != 0) {
                        print STDERR "mr $action: failed ($ret)\n" if $verbose;
-                       push @failed, $topdir.$subdir;
+                       push @failed, $dir;
                        if ($ret >> 8 != 0) {
                                print STDERR "mr $action: command failed\n";
                        }
                $dir="";
        }
        else {
-               # $f might be a symlink
+               if (! -e $f) {
+                       return;
+               }
+
                my $absf=abs_path($f);
                if ($loaded{$absf}) {
                        return;
                my $parent=$dir;
                while ($parent=~s/^(.*)\/[^\/]+\/?$/$1/) {
                        if (exists $config{$parent} &&
-                           exists $config{$parent}{default}) {
-                               $config{$dir}{default}={ %{$config{$parent}{default}} };
+                           exists $config{$parent}{DEFAULT}) {
+                               $config{$dir}{DEFAULT}={ %{$config{$parent}{DEFAULT}} };
                                last;
                        }
                }
                        my $value=$2;
 
                        # continuation line
-                       while ($value=~/(.*)\\$/) {
-                               $value=$1.<$in>;
+                       while ($value=~/(.*)\\$/s) {
+                               $value=$1."\n".<$in>;
                                chomp $value;
                        }
 
                        if (! defined $section) {
                                die "$f line $.: parameter ($parameter) not in section\n";
                        }
-                       if ($section ne 'alias' &&
+                       if ($section ne 'ALIAS' &&
                            ! exists $config{$dir}{$section} &&
-                           exists $config{$dir}{default}) {
+                           exists $config{$dir}{DEFAULT}) {
                                # copy in defaults
-                               $config{$dir}{$section}={ %{$config{$dir}{default}} };
+                               $config{$dir}{$section}={ %{$config{$dir}{DEFAULT}} };
                        }
-                       if ($section eq 'alias') {
+                       if ($section eq 'ALIAS') {
                                $alias{$parameter}=$value;
                        }
                        elsif ($parameter eq 'lib') {
-                               $config{$dir}{$section}{lib}.=$value." ; ";
+                               $config{$dir}{$section}{lib}.=$value."\n";
                        }
                        else {
                                $config{$dir}{$section}{$parameter}=$value;
                                $knownactions{$parameter}=1;
                                if ($parameter eq 'chain' &&
-                                   length $dir && $section ne "default" &&
+                                   length $dir && $section ne "DEFAULT" &&
                                    -e $dir.$section."/.mrconfig" &&
                                    system($value) >> 8 == 0) {
                                        push @toload, $dir.$section."/.mrconfig";
        }
 }
 
+sub modifyconfig {
+       my $f=shift;
+       # the section to modify or add
+       my $targetsection=shift;
+       # fields to change in the section
+       # To remove a field, set its value to "".
+       my %changefields=@_;
+
+       my @lines;
+       my @out;
+
+       if (-e $f) {
+               open(my $in, "<", $f) || die "mr: open $f: $!\n";
+               @lines=<$in>;
+               close $in;
+       }
+
+       my $addfields=sub {
+               my @blanks;
+               while ($out[$#out] =~ /^\s*$/) {
+                       unshift @blanks, pop @out;
+               }
+               foreach my $field (sort keys %changefields) {
+                       if (length $changefields{$field}) {
+                               push @out, "$field = $changefields{$field}\n";
+                       }
+               }
+               push @out, @blanks;
+       };
+
+       my $section;
+       while (@lines) {
+               $_=shift(@lines);
+
+               if (/^\s*\#/ || /^\s*$/) {
+                       push @out, $_;
+               }
+               elsif (/^\s*\[([^\]]*)\]\s*$/) {
+                       if (defined $section && 
+                           $section eq $targetsection) {
+                               $addfields->();
+                       }
+
+                       $section=$1;
+
+                       push @out, $_;
+               }
+               elsif (/^\s*(\w+)\s*=\s(.*)/) {
+                       my $parameter=$1;
+                       my $value=$2;
+
+                       # continuation line
+                       while ($value=~/(.*\\)$/s) {
+                               $value=$1."\n".shift(@lines);
+                               chomp $value;
+                       }
+
+                       if ($section eq $targetsection) {
+                               if (exists $changefields{$parameter}) {
+                                       if (length $changefields{$parameter}) {
+                                               $value=$changefields{$parameter};
+                                       }
+                                       delete $changefields{$parameter};
+                               }
+                       }
+
+                       push @out, "$parameter = $value\n";
+               }
+       }
+
+       if (defined $section && 
+           $section eq $targetsection) {
+                       $addfields->();
+       }
+       elsif (%changefields) {
+               push @out, "\n[$targetsection]\n";
+               foreach my $field (sort keys %changefields) {
+                       if (length $changefields{$field}) {
+                               push @out, "$field = $changefields{$field}\n";
+                       }
+               }
+       }
+
+       open(my $out, ">", $f) || die "mr: write $f: $!\n";
+       print $out @out;
+       close $out;     
+}
+
 # Finally, some useful actions that mr knows about by default.
 # These can be overridden in ~/.mrconfig.
 __DATA__
-[alias]
+[ALIAS]
        co = checkout
        ci = commit
        ls = list
 
-[default]
-lib = \
-       error() { \
-               echo "mr: $@" >&2; \
-               exit 1; \
+[DEFAULT]
+lib =                                                                  \
+       error() {                                                       \
+               echo "mr: $@" >&2                                       \
+               exit 1                                                  \
+       }                                                               \
+       hours_since() {                                                 \
+               for dir in .git .svn .bzr CVS; do                       \
+                       if [ -e "$MR_REPO/$dir" ]; then                 \
+                               flagfile="$MR_REPO/$dir/.mr_last$1"     \
+                               break                                   \
+                       fi                                              \
+               done                                                    \
+               if [ -z "$flagfile" ]; then                             \
+                       error "cannot determine flag filename"          \
+               fi                                                      \
+               perl -wle 'print -f shift() ? int((-M _) * 24) : 9999' "$flagfile" \
+               touch "$flagfile"                                       \
        }
 
-update = \
-       if [ -d "$MR_REPO"/.svn ]; then \
-               svn update "$@"; \
-       elif [ -d "$MR_REPO"/.git ]; then \
-               git pull origin master "$@"; \
-       elif [ -d "$MR_REPO"/.bzr ]; then \
-               bzr merge "$@"; \
-       elif [ -d "$MR_REPO"/CVS ]; then \
-               cvs update "$@"; \
-       else \
-               error "unknown repo type"; \
+update =                                                               \
+       if [ -d "$MR_REPO"/.svn ]; then                                 \
+               svn update "$@"                                         \
+       elif [ -d "$MR_REPO"/.git ]; then                               \
+               git pull origin master "$@"                             \
+       elif [ -d "$MR_REPO"/.bzr ]; then                               \
+               bzr merge "$@"                                          \
+       elif [ -d "$MR_REPO"/CVS ]; then                                \
+               cvs update "$@"                                         \
+       else                                                            \
+               error "unknown repo type"                               \
        fi
-status = \
-       if [ -d "$MR_REPO"/.svn ]; then \
-               svn status "$@"; \
-       elif [ -d "$MR_REPO"/.git ]; then \
-               git status "$@" || true; \
-       elif [ -d "$MR_REPO"/.bzr ]; then \
-               bzr status "$@"; \
-       elif [ -d "$MR_REPO"/CVS ]; then \
-               cvs status "$@"; \
-       else \
-               error "unknown repo type"; \
+status =                                                               \
+       if [ -d "$MR_REPO"/.svn ]; then                                 \
+               svn status "$@"                                         \
+       elif [ -d "$MR_REPO"/.git ]; then                               \
+               git status "$@" || true                                 \
+       elif [ -d "$MR_REPO"/.bzr ]; then                               \
+               bzr status "$@"                                         \
+       elif [ -d "$MR_REPO"/CVS ]; then                                \
+               cvs status "$@"                                         \
+       else                                                            \
+               error "unknown repo type"                               \
        fi
-commit = \
-       if [ -d "$MR_REPO"/.svn ]; then \
-               svn commit "$@"; \
-       elif [ -d "$MR_REPO"/.git ]; then \
-               git commit -a "$@" && git push --all; \
-       elif [ -d "$MR_REPO"/.bzr ]; then \
-               bzr commit "$@" && bzr push; \
-       elif [ -d "$MR_REPO"/CVS ]; then \
-               cvs commit "$@"; \
-       else \
-               error "unknown repo type"; \
+commit =                                                               \
+       if [ -d "$MR_REPO"/.svn ]; then                                 \
+               svn commit "$@"                                         \
+       elif [ -d "$MR_REPO"/.git ]; then                               \
+               git commit -a "$@" && git push --all                    \
+       elif [ -d "$MR_REPO"/.bzr ]; then                               \
+               bzr commit "$@" && bzr push                             \
+       elif [ -d "$MR_REPO"/CVS ]; then                                \
+               cvs commit "$@"                                         \
+       else                                                            \
+               error "unknown repo type"                               \
        fi
-diff = \
-       if [ -d "$MR_REPO"/.svn ]; then \
-               svn diff "$@"; \
-       elif [ -d "$MR_REPO"/.git ]; then \
-               git diff "$@"; \
-       elif [ -d "$MR_REPO"/.bzr ]; then \
-               bzr diff "$@"; \
-       elif [ -d "$MR_REPO"/CVS ]; then \
-               cvs diff "$@"; \
-       else \
-               error "unknown repo type"; \
+diff =                                                                 \
+       if [ -d "$MR_REPO"/.svn ]; then                                 \
+               svn diff "$@"                                           \
+       elif [ -d "$MR_REPO"/.git ]; then                               \
+               git diff "$@"                                           \
+       elif [ -d "$MR_REPO"/.bzr ]; then                               \
+               bzr diff "$@"                                           \
+       elif [ -d "$MR_REPO"/CVS ]; then                                \
+               cvs diff "$@"                                           \
+       else                                                            \
+               error "unknown repo type"                               \
        fi
-log = \
-       if [ -d "$MR_REPO"/.svn ]; then \
-               svn log"$@"; \
-       elif [ -d "$MR_REPO"/.git ]; then \
-               git log "$@"; \
-       elif [ -d "$MR_REPO"/.bzr ]; then \
-               bzr log "$@"; \
-       elif [ -d "$MR_REPO"/CVS ]; then \
-               cvs log "$@"; \
-       else \
-               error "unknown repo type"; \
+log =                                                                  \
+       if [ -d "$MR_REPO"/.svn ]; then                                 \
+               svn log"$@"                                             \
+       elif [ -d "$MR_REPO"/.git ]; then                               \
+               git log "$@"                                            \
+       elif [ -d "$MR_REPO"/.bzr ]; then                               \
+               bzr log "$@"                                            \
+       elif [ -d "$MR_REPO"/CVS ]; then                                \
+               cvs log "$@"                                            \
+       else                                                            \
+               error "unknown repo type"                               \
+       fi
+register =                                                             \
+       if [ -n "$1" ]; then                                            \
+               cd "$1"                                                 \
+       fi                                                              \
+       basedir="$(basename $(pwd))"                                    \
+       if [ -d .svn ]; then                                            \
+               url=$(LANG=C svn info . |                               \
+                     grep -i ^URL: | cut -d ' ' -f 2)                  \
+               if [ -z "$url" ]; then                                  \
+                       error "cannot determine svn url"                \
+               fi                                                      \
+               echo "Registering svn url: $url"                        \
+               mr config "$(pwd)" checkout="svn co $url $basedir"      \
+       elif [ -d .git ]; then                                          \
+               url=$(LANG=C git-config --get remote.origin.url)        \
+               if [ -z "$url" ]; then                                  \
+                       error "cannot determine git url"                \
+               fi                                                      \
+               echo "Registering git url: $url"                        \
+               mr config "$(pwd)" checkout="git clone $url $basedir"   \
+       elif [ -d .bzr ]; then                                          \
+               url=$(cat .bzr/branch/parent)                           \
+               if [ -z "$url" ]; then                                  \
+                       error "cannot determine bzr url"                \
+               fi                                                      \
+               echo "Registering bzr url: $url"                        \
+               mr config "$(pwd)" checkout="bzr clone $url $basedir"   \
+       else                                                            \
+               error "unable to register this repo type"               \
        fi
 list = true
-
-help = \
-       if [ ! -e "$MR_PATH" ]; then \
-               error "cannot find program path";\
-       fi; \
-       (pod2man -c mr "$MR_PATH" | man -l -) || \
+config = 
+help =                                                                 \
+       if [ ! -e "$MR_PATH" ]; then                                    \
+               error "cannot find program path"                        \
+       fi                                                              \
+       (pod2man -c mr "$MR_PATH" | man -l -) ||                        \
                error "pod2man or man failed"
 
 ed = echo "A horse is a horse, of course, of course.."