Andrew's git - gitweb.git/blob - contrib/hooks/post-receive-email

   1#!/bin/sh
   2#
   3# Copyright (c) 2007 Andy Parkins
   4#
   5# An example hook script to mail out commit update information.  This hook
   6# sends emails listing new revisions to the repository introduced by the
   7# change being reported.  The rule is that (for branch updates) each commit
   8# will appear on one email and one email only.
   9#
  10# This hook is stored in the contrib/hooks directory.  Your distribution
  11# will have put this somewhere standard.  You should make this script
  12# executable then link to it in the repository you would like to use it in.
  13# For example, on debian the hook is stored in
  14# /usr/share/git-core/contrib/hooks/post-receive-email:
  15#
  16#  chmod a+x post-receive-email
  17#  cd /path/to/your/repository.git
  18#  ln -sf /usr/share/git-core/contrib/hooks/post-receive-email hooks/post-receive
  19#
  20# This hook script assumes it is enabled on the central repository of a
  21# project, with all users pushing only to it and not between each other.  It
  22# will still work if you don't operate in that style, but it would become
  23# possible for the email to be from someone other than the person doing the
  24# push.
  25#
  26# To help with debugging and use on pre-v1.5.1 git servers, this script will
  27# also obey the interface of hooks/update, taking its arguments on the
  28# command line.  Unfortunately, hooks/update is called once for each ref.
  29# To avoid firing one email per ref, this script just prints its output to
  30# the screen when used in this mode.  The output can then be redirected if
  31# wanted.
  32#
  33# Config
  34# ------
  35# hooks.mailinglist
  36#   This is the list that all pushes will go to; leave it blank to not send
  37#   emails for every ref update.
  38# hooks.announcelist
  39#   This is the list that all pushes of annotated tags will go to.  Leave it
  40#   blank to default to the mailinglist field.  The announce emails lists
  41#   the short log summary of the changes since the last annotated tag.
  42# hooks.envelopesender
  43#   If set then the -f option is passed to sendmail to allow the envelope
  44#   sender address to be set
  45# hooks.emailprefix
  46#   All emails have their subjects prefixed with this prefix, or "[SCM]"
  47#   if emailprefix is unset, to aid filtering
  48# hooks.showrev
  49#   The shell command used to format each revision in the email, with
  50#   "%s" replaced with the commit id.  Defaults to "git rev-list -1
  51#   --pretty %s", displaying the commit id, author, date and log
  52#   message.  To list full patches separated by a blank line, you
  53#   could set this to "git show -C %s; echo".
  54#   To list a gitweb/cgit URL *and* a full patch for each change set, use this:
  55#     "t=%s; printf 'http://.../?id=%%s' \$t; echo;echo; git show -C \$t; echo"
  56#   Be careful if "..." contains things that will be expanded by shell "eval"
  57#   or printf.
  58# hooks.emailmaxlines
  59#   The maximum number of lines that should be included in the generated
  60#   email body. If not specified, there is no limit.
  61#   Lines beyond the limit are suppressed and counted, and a final
  62#   line is added indicating the number of suppressed lines.
  63# hooks.diffopts
  64#   Alternate options for the git diff-tree invocation that shows changes.
  65#   Default is "--stat --summary --find-copies-harder". Add -p to those
  66#   options to include a unified diff of changes in addition to the usual
  67#   summary output.
  68#
  69# Notes
  70# -----
  71# All emails include the headers "X-Git-Refname", "X-Git-Oldrev",
  72# "X-Git-Newrev", and "X-Git-Reftype" to enable fine tuned filtering and
  73# give information for debugging.
  74#
  75
  76# ---------------------------- Functions
  77
  78#
  79# Function to prepare for email generation. This decides what type
  80# of update this is and whether an email should even be generated.
  81#
  82prep_for_email()
  83{
  84        # --- Arguments
  85        oldrev=$(git rev-parse $1)
  86        newrev=$(git rev-parse $2)
  87        refname="$3"
  88        maxlines=$4
  89
  90        # --- Interpret
  91        # 0000->1234 (create)
  92        # 1234->2345 (update)
  93        # 2345->0000 (delete)
  94        if expr "$oldrev" : '0*$' >/dev/null
  95        then
  96                change_type="create"
  97        else
  98                if expr "$newrev" : '0*$' >/dev/null
  99                then
 100                        change_type="delete"
 101                else
 102                        change_type="update"
 103                fi
 104        fi
 105
 106        # --- Get the revision types
 107        newrev_type=$(git cat-file -t $newrev 2> /dev/null)
 108        oldrev_type=$(git cat-file -t "$oldrev" 2> /dev/null)
 109        case "$change_type" in
 110        create|update)
 111                rev="$newrev"
 112                rev_type="$newrev_type"
 113                ;;
 114        delete)
 115                rev="$oldrev"
 116                rev_type="$oldrev_type"
 117                ;;
 118        esac
 119
 120        # The revision type tells us what type the commit is, combined with
 121        # the location of the ref we can decide between
 122        #  - working branch
 123        #  - tracking branch
 124        #  - unannoted tag
 125        #  - annotated tag
 126        case "$refname","$rev_type" in
 127                refs/tags/*,commit)
 128                        # un-annotated tag
 129                        refname_type="tag"
 130                        short_refname=${refname##refs/tags/}
 131                        ;;
 132                refs/tags/*,tag)
 133                        # annotated tag
 134                        refname_type="annotated tag"
 135                        short_refname=${refname##refs/tags/}
 136                        # change recipients
 137                        if [ -n "$announcerecipients" ]; then
 138                                recipients="$announcerecipients"
 139                        fi
 140                        ;;
 141                refs/heads/*,commit)
 142                        # branch
 143                        refname_type="branch"
 144                        short_refname=${refname##refs/heads/}
 145                        ;;
 146                refs/remotes/*,commit)
 147                        # tracking branch
 148                        refname_type="tracking branch"
 149                        short_refname=${refname##refs/remotes/}
 150                        echo >&2 "*** Push-update of tracking branch, $refname"
 151                        echo >&2 "***  - no email generated."
 152                        return 1
 153                        ;;
 154                *)
 155                        # Anything else (is there anything else?)
 156                        echo >&2 "*** Unknown type of update to $refname ($rev_type)"
 157                        echo >&2 "***  - no email generated"
 158                        return 1
 159                        ;;
 160        esac
 161
 162        # Check if we've got anyone to send to
 163        if [ -z "$recipients" ]; then
 164                case "$refname_type" in
 165                        "annotated tag")
 166                                config_name="hooks.announcelist"
 167                                ;;
 168                        *)
 169                                config_name="hooks.mailinglist"
 170                                ;;
 171                esac
 172                echo >&2 "*** $config_name is not set so no email will be sent"
 173                echo >&2 "*** for $refname update $oldrev->$newrev"
 174                return 1
 175        fi
 176
 177        return 0
 178}
 179
 180#
 181# Top level email generation function.  This calls the appropriate
 182# body-generation routine after outputting the common header.
 183#
 184# Note this function doesn't actually generate any email output, that is
 185# taken care of by the functions it calls:
 186#  - generate_email_header
 187#  - generate_create_XXXX_email
 188#  - generate_update_XXXX_email
 189#  - generate_delete_XXXX_email
 190#  - generate_email_footer
 191#
 192# Note also that this function cannot 'exit' from the script; when this
 193# function is running (in hook script mode), the send_mail() function
 194# is already executing in another process, connected via a pipe, and
 195# if this function exits without, whatever has been generated to that
 196# point will be sent as an email... even if nothing has been generated.
 197#
 198generate_email()
 199{
 200        # Email parameters
 201        # The email subject will contain the best description of the ref
 202        # that we can build from the parameters
 203        describe=$(git describe $rev 2>/dev/null)
 204        if [ -z "$describe" ]; then
 205                describe=$rev
 206        fi
 207
 208        generate_email_header
 209
 210        # Call the correct body generation function
 211        fn_name=general
 212        case "$refname_type" in
 213        "tracking branch"|branch)
 214                fn_name=branch
 215                ;;
 216        "annotated tag")
 217                fn_name=atag
 218                ;;
 219        esac
 220
 221        if [ -z "$maxlines" ]; then
 222                generate_${change_type}_${fn_name}_email
 223        else
 224                generate_${change_type}_${fn_name}_email | limit_lines $maxlines
 225        fi
 226
 227        generate_email_footer
 228}
 229
 230generate_email_header()
 231{
 232        # --- Email (all stdout will be the email)
 233        # Generate header
 234        cat <<-EOF
 235        To: $recipients
 236        Subject: ${emailprefix}$projectdesc $refname_type $short_refname ${change_type}d. $describe
 237        X-Git-Refname: $refname
 238        X-Git-Reftype: $refname_type
 239        X-Git-Oldrev: $oldrev
 240        X-Git-Newrev: $newrev
 241
 242        This is an automated email from the git hooks/post-receive script. It was
 243        generated because a ref change was pushed to the repository containing
 244        the project "$projectdesc".
 245
 246        The $refname_type, $short_refname has been ${change_type}d
 247        EOF
 248}
 249
 250generate_email_footer()
 251{
 252        SPACE=" "
 253        cat <<-EOF
 254
 255
 256        hooks/post-receive
 257        --${SPACE}
 258        $projectdesc
 259        EOF
 260}
 261
 262# --------------- Branches
 263
 264#
 265# Called for the creation of a branch
 266#
 267generate_create_branch_email()
 268{
 269        # This is a new branch and so oldrev is not valid
 270        echo "        at  $newrev ($newrev_type)"
 271        echo ""
 272
 273        echo $LOGBEGIN
 274        show_new_revisions
 275        echo $LOGEND
 276}
 277
 278#
 279# Called for the change of a pre-existing branch
 280#
 281generate_update_branch_email()
 282{
 283        # Consider this:
 284        #   1 --- 2 --- O --- X --- 3 --- 4 --- N
 285        #
 286        # O is $oldrev for $refname
 287        # N is $newrev for $refname
 288        # X is a revision pointed to by some other ref, for which we may
 289        #   assume that an email has already been generated.
 290        # In this case we want to issue an email containing only revisions
 291        # 3, 4, and N.  Given (almost) by
 292        #
 293        #  git rev-list N ^O --not --all
 294        #
 295        # The reason for the "almost", is that the "--not --all" will take
 296        # precedence over the "N", and effectively will translate to
 297        #
 298        #  git rev-list N ^O ^X ^N
 299        #
 300        # So, we need to build up the list more carefully.  git rev-parse
 301        # will generate a list of revs that may be fed into git rev-list.
 302        # We can get it to make the "--not --all" part and then filter out
 303        # the "^N" with:
 304        #
 305        #  git rev-parse --not --all | grep -v N
 306        #
 307        # Then, using the --stdin switch to git rev-list we have effectively
 308        # manufactured
 309        #
 310        #  git rev-list N ^O ^X
 311        #
 312        # This leaves a problem when someone else updates the repository
 313        # while this script is running.  Their new value of the ref we're
 314        # working on would be included in the "--not --all" output; and as
 315        # our $newrev would be an ancestor of that commit, it would exclude
 316        # all of our commits.  What we really want is to exclude the current
 317        # value of $refname from the --not list, rather than N itself.  So:
 318        #
 319        #  git rev-parse --not --all | grep -v $(git rev-parse $refname)
 320        #
 321        # Get's us to something pretty safe (apart from the small time
 322        # between refname being read, and git rev-parse running - for that,
 323        # I give up)
 324        #
 325        #
 326        # Next problem, consider this:
 327        #   * --- B --- * --- O ($oldrev)
 328        #          \
 329        #           * --- X --- * --- N ($newrev)
 330        #
 331        # That is to say, there is no guarantee that oldrev is a strict
 332        # subset of newrev (it would have required a --force, but that's
 333        # allowed).  So, we can't simply say rev-list $oldrev..$newrev.
 334        # Instead we find the common base of the two revs and list from
 335        # there.
 336        #
 337        # As above, we need to take into account the presence of X; if
 338        # another branch is already in the repository and points at some of
 339        # the revisions that we are about to output - we don't want them.
 340        # The solution is as before: git rev-parse output filtered.
 341        #
 342        # Finally, tags: 1 --- 2 --- O --- T --- 3 --- 4 --- N
 343        #
 344        # Tags pushed into the repository generate nice shortlog emails that
 345        # summarise the commits between them and the previous tag.  However,
 346        # those emails don't include the full commit messages that we output
 347        # for a branch update.  Therefore we still want to output revisions
 348        # that have been output on a tag email.
 349        #
 350        # Luckily, git rev-parse includes just the tool.  Instead of using
 351        # "--all" we use "--branches"; this has the added benefit that
 352        # "remotes/" will be ignored as well.
 353
 354        # List all of the revisions that were removed by this update, in a
 355        # fast-forward update, this list will be empty, because rev-list O
 356        # ^N is empty.  For a non-fast-forward, O ^N is the list of removed
 357        # revisions
 358        fast_forward=""
 359        rev=""
 360        for rev in $(git rev-list $newrev..$oldrev)
 361        do
 362                revtype=$(git cat-file -t "$rev")
 363                echo "  discards  $rev ($revtype)"
 364        done
 365        if [ -z "$rev" ]; then
 366                fast_forward=1
 367        fi
 368
 369        # List all the revisions from baserev to newrev in a kind of
 370        # "table-of-contents"; note this list can include revisions that
 371        # have already had notification emails and is present to show the
 372        # full detail of the change from rolling back the old revision to
 373        # the base revision and then forward to the new revision
 374        for rev in $(git rev-list $oldrev..$newrev)
 375        do
 376                revtype=$(git cat-file -t "$rev")
 377                echo "       via  $rev ($revtype)"
 378        done
 379
 380        if [ "$fast_forward" ]; then
 381                echo "      from  $oldrev ($oldrev_type)"
 382        else
 383                #  1. Existing revisions were removed.  In this case newrev
 384                #     is a subset of oldrev - this is the reverse of a
 385                #     fast-forward, a rewind
 386                #  2. New revisions were added on top of an old revision,
 387                #     this is a rewind and addition.
 388
 389                # (1) certainly happened, (2) possibly.  When (2) hasn't
 390                # happened, we set a flag to indicate that no log printout
 391                # is required.
 392
 393                echo ""
 394
 395                # Find the common ancestor of the old and new revisions and
 396                # compare it with newrev
 397                baserev=$(git merge-base $oldrev $newrev)
 398                rewind_only=""
 399                if [ "$baserev" = "$newrev" ]; then
 400                        echo "This update discarded existing revisions and left the branch pointing at"
 401                        echo "a previous point in the repository history."
 402                        echo ""
 403                        echo " * -- * -- N ($newrev)"
 404                        echo "            \\"
 405                        echo "             O -- O -- O ($oldrev)"
 406                        echo ""
 407                        echo "The removed revisions are not necessarilly gone - if another reference"
 408                        echo "still refers to them they will stay in the repository."
 409                        rewind_only=1
 410                else
 411                        echo "This update added new revisions after undoing existing revisions.  That is"
 412                        echo "to say, the old revision is not a strict subset of the new revision.  This"
 413                        echo "situation occurs when you --force push a change and generate a repository"
 414                        echo "containing something like this:"
 415                        echo ""
 416                        echo " * -- * -- B -- O -- O -- O ($oldrev)"
 417                        echo "            \\"
 418                        echo "             N -- N -- N ($newrev)"
 419                        echo ""
 420                        echo "When this happens we assume that you've already had alert emails for all"
 421                        echo "of the O revisions, and so we here report only the revisions in the N"
 422                        echo "branch from the common base, B."
 423                fi
 424        fi
 425
 426        echo ""
 427        if [ -z "$rewind_only" ]; then
 428                echo "Those revisions listed above that are new to this repository have"
 429                echo "not appeared on any other notification email; so we list those"
 430                echo "revisions in full, below."
 431
 432                echo ""
 433                echo $LOGBEGIN
 434                show_new_revisions
 435
 436                # XXX: Need a way of detecting whether git rev-list actually
 437                # outputted anything, so that we can issue a "no new
 438                # revisions added by this update" message
 439
 440                echo $LOGEND
 441        else
 442                echo "No new revisions were added by this update."
 443        fi
 444
 445        # The diffstat is shown from the old revision to the new revision.
 446        # This is to show the truth of what happened in this change.
 447        # There's no point showing the stat from the base to the new
 448        # revision because the base is effectively a random revision at this
 449        # point - the user will be interested in what this revision changed
 450        # - including the undoing of previous revisions in the case of
 451        # non-fast-forward updates.
 452        echo ""
 453        echo "Summary of changes:"
 454        git diff-tree $diffopts $oldrev..$newrev
 455}
 456
 457#
 458# Called for the deletion of a branch
 459#
 460generate_delete_branch_email()
 461{
 462        echo "       was  $oldrev"
 463        echo ""
 464        echo $LOGEND
 465        git show -s --pretty=oneline $oldrev
 466        echo $LOGEND
 467}
 468
 469# --------------- Annotated tags
 470
 471#
 472# Called for the creation of an annotated tag
 473#
 474generate_create_atag_email()
 475{
 476        echo "        at  $newrev ($newrev_type)"
 477
 478        generate_atag_email
 479}
 480
 481#
 482# Called for the update of an annotated tag (this is probably a rare event
 483# and may not even be allowed)
 484#
 485generate_update_atag_email()
 486{
 487        echo "        to  $newrev ($newrev_type)"
 488        echo "      from  $oldrev (which is now obsolete)"
 489
 490        generate_atag_email
 491}
 492
 493#
 494# Called when an annotated tag is created or changed
 495#
 496generate_atag_email()
 497{
 498        # Use git for-each-ref to pull out the individual fields from the
 499        # tag
 500        eval $(git for-each-ref --shell --format='
 501        tagobject=%(*objectname)
 502        tagtype=%(*objecttype)
 503        tagger=%(taggername)
 504        tagged=%(taggerdate)' $refname
 505        )
 506
 507        echo "   tagging  $tagobject ($tagtype)"
 508        case "$tagtype" in
 509        commit)
 510
 511                # If the tagged object is a commit, then we assume this is a
 512                # release, and so we calculate which tag this tag is
 513                # replacing
 514                prevtag=$(git describe --abbrev=0 $newrev^ 2>/dev/null)
 515
 516                if [ -n "$prevtag" ]; then
 517                        echo "  replaces  $prevtag"
 518                fi
 519                ;;
 520        *)
 521                echo "    length  $(git cat-file -s $tagobject) bytes"
 522                ;;
 523        esac
 524        echo " tagged by  $tagger"
 525        echo "        on  $tagged"
 526
 527        echo ""
 528        echo $LOGBEGIN
 529
 530        # Show the content of the tag message; this might contain a change
 531        # log or release notes so is worth displaying.
 532        git cat-file tag $newrev | sed -e '1,/^$/d'
 533
 534        echo ""
 535        case "$tagtype" in
 536        commit)
 537                # Only commit tags make sense to have rev-list operations
 538                # performed on them
 539                if [ -n "$prevtag" ]; then
 540                        # Show changes since the previous release
 541                        git rev-list --pretty=short "$prevtag..$newrev" | git shortlog
 542                else
 543                        # No previous tag, show all the changes since time
 544                        # began
 545                        git rev-list --pretty=short $newrev | git shortlog
 546                fi
 547                ;;
 548        *)
 549                # XXX: Is there anything useful we can do for non-commit
 550                # objects?
 551                ;;
 552        esac
 553
 554        echo $LOGEND
 555}
 556
 557#
 558# Called for the deletion of an annotated tag
 559#
 560generate_delete_atag_email()
 561{
 562        echo "       was  $oldrev"
 563        echo ""
 564        echo $LOGEND
 565        git show -s --pretty=oneline $oldrev
 566        echo $LOGEND
 567}
 568
 569# --------------- General references
 570
 571#
 572# Called when any other type of reference is created (most likely a
 573# non-annotated tag)
 574#
 575generate_create_general_email()
 576{
 577        echo "        at  $newrev ($newrev_type)"
 578
 579        generate_general_email
 580}
 581
 582#
 583# Called when any other type of reference is updated (most likely a
 584# non-annotated tag)
 585#
 586generate_update_general_email()
 587{
 588        echo "        to  $newrev ($newrev_type)"
 589        echo "      from  $oldrev"
 590
 591        generate_general_email
 592}
 593
 594#
 595# Called for creation or update of any other type of reference
 596#
 597generate_general_email()
 598{
 599        # Unannotated tags are more about marking a point than releasing a
 600        # version; therefore we don't do the shortlog summary that we do for
 601        # annotated tags above - we simply show that the point has been
 602        # marked, and print the log message for the marked point for
 603        # reference purposes
 604        #
 605        # Note this section also catches any other reference type (although
 606        # there aren't any) and deals with them in the same way.
 607
 608        echo ""
 609        if [ "$newrev_type" = "commit" ]; then
 610                echo $LOGBEGIN
 611                git show --no-color --root -s --pretty=medium $newrev
 612                echo $LOGEND
 613        else
 614                # What can we do here?  The tag marks an object that is not
 615                # a commit, so there is no log for us to display.  It's
 616                # probably not wise to output git cat-file as it could be a
 617                # binary blob.  We'll just say how big it is
 618                echo "$newrev is a $newrev_type, and is $(git cat-file -s $newrev) bytes long."
 619        fi
 620}
 621
 622#
 623# Called for the deletion of any other type of reference
 624#
 625generate_delete_general_email()
 626{
 627        echo "       was  $oldrev"
 628        echo ""
 629        echo $LOGEND
 630        git show -s --pretty=oneline $oldrev
 631        echo $LOGEND
 632}
 633
 634
 635# --------------- Miscellaneous utilities
 636
 637#
 638# Show new revisions as the user would like to see them in the email.
 639#
 640show_new_revisions()
 641{
 642        # This shows all log entries that are not already covered by
 643        # another ref - i.e. commits that are now accessible from this
 644        # ref that were previously not accessible
 645        # (see generate_update_branch_email for the explanation of this
 646        # command)
 647
 648        # Revision range passed to rev-list differs for new vs. updated
 649        # branches.
 650        if [ "$change_type" = create ]
 651        then
 652                # Show all revisions exclusive to this (new) branch.
 653                revspec=$newrev
 654        else
 655                # Branch update; show revisions not part of $oldrev.
 656                revspec=$oldrev..$newrev
 657        fi
 658
 659        other_branches=$(git for-each-ref --format='%(refname)' refs/heads/ |
 660            grep -F -v $refname)
 661        git rev-parse --not $other_branches |
 662        if [ -z "$custom_showrev" ]
 663        then
 664                git rev-list --pretty --stdin $revspec
 665        else
 666                git rev-list --stdin $revspec |
 667                while read onerev
 668                do
 669                        eval $(printf "$custom_showrev" $onerev)
 670                done
 671        fi
 672}
 673
 674
 675limit_lines()
 676{
 677        lines=0
 678        skipped=0
 679        while IFS="" read -r line; do
 680                lines=$((lines + 1))
 681                if [ $lines -gt $1 ]; then
 682                        skipped=$((skipped + 1))
 683                else
 684                        printf "%s\n" "$line"
 685                fi
 686        done
 687        if [ $skipped -ne 0 ]; then
 688                echo "... $skipped lines suppressed ..."
 689        fi
 690}
 691
 692
 693send_mail()
 694{
 695        if [ -n "$envelopesender" ]; then
 696                /usr/sbin/sendmail -t -f "$envelopesender"
 697        else
 698                /usr/sbin/sendmail -t
 699        fi
 700}
 701
 702# ---------------------------- main()
 703
 704# --- Constants
 705LOGBEGIN="- Log -----------------------------------------------------------------"
 706LOGEND="-----------------------------------------------------------------------"
 707
 708# --- Config
 709# Set GIT_DIR either from the working directory, or from the environment
 710# variable.
 711GIT_DIR=$(git rev-parse --git-dir 2>/dev/null)
 712if [ -z "$GIT_DIR" ]; then
 713        echo >&2 "fatal: post-receive: GIT_DIR not set"
 714        exit 1
 715fi
 716
 717projectdesc=$(sed -ne '1p' "$GIT_DIR/description" 2>/dev/null)
 718# Check if the description is unchanged from it's default, and shorten it to
 719# a more manageable length if it is
 720if expr "$projectdesc" : "Unnamed repository.*$" >/dev/null
 721then
 722        projectdesc="UNNAMED PROJECT"
 723fi
 724
 725recipients=$(git config hooks.mailinglist)
 726announcerecipients=$(git config hooks.announcelist)
 727envelopesender=$(git config hooks.envelopesender)
 728emailprefix=$(git config hooks.emailprefix || echo '[SCM] ')
 729custom_showrev=$(git config hooks.showrev)
 730maxlines=$(git config hooks.emailmaxlines)
 731diffopts=$(git config hooks.diffopts)
 732: ${diffopts:="--stat --summary --find-copies-harder"}
 733
 734# --- Main loop
 735# Allow dual mode: run from the command line just like the update hook, or
 736# if no arguments are given then run as a hook script
 737if [ -n "$1" -a -n "$2" -a -n "$3" ]; then
 738        # Output to the terminal in command line mode - if someone wanted to
 739        # resend an email; they could redirect the output to sendmail
 740        # themselves
 741        prep_for_email $2 $3 $1 && PAGER= generate_email
 742else
 743        while read oldrev newrev refname
 744        do
 745                prep_for_email $oldrev $newrev $refname || continue
 746                generate_email $maxlines | send_mail
 747        done
 748fi