#!/opt/bin/perl
#
#########################################################################
#                                                                       #
# Program to monitor files and to notify any changes to the user's TTY  #
#                                                                       #
#########################################################################
#                                                                       #
#   Version 1.0     -   Written 01.03.96 by Steffen Beyer               #
#                                                                       #
#########################################################################
#                                                                       #
#   Copyright (C) 1995 by software design & management GmbH & Co. KG    #
#                                                                       #
#########################################################################

# Configure here the name(s) and owner(s) of the file(s) to monitor:

$path = '/u/sysadm';

# (This is the common path for the following files. It may be left empty
# if the files are specified with absolute paths.)

push(@files, 'AL');  push(@users, 'alex');
push(@files, 'AS');  push(@users, 'schnagl');
push(@files, 'CB');  push(@users, 'bach');
push(@files, 'CH');  push(@users, 'joker');
push(@files, 'DB');  push(@users, 'dabe');
push(@files, 'HB');  push(@users, 'hebu');
push(@files, 'JP');  push(@users, 'pichel');
push(@files, 'KF');  push(@users, 'happy');
push(@files, 'MF');  push(@users, 'marfil');
push(@files, 'MS');  push(@users, 'blacky');
push(@files, 'RSE'); push(@users, 'rse');
push(@files, 'SB');  push(@users, 'sb');
push(@files, 'SH');  push(@users, 'susanne');
push(@files, 'TT');  push(@users, 'tommy');
push(@files, 'UB');  push(@users, 'uwe2');
push(@files, 'WW');  push(@users, 'wolfgang');
push(@files, 'XW');  push(@users, 'wunix');

# Some defaults:

$version = 'version 1.0';

$self = $0;
$self =~ s!^.*/!!;

# Determine user's ID numbers:

for ( $i = 0; $i <= $#users; $i++ )
{
    $user = $users[$i];
    if (($uid) = (getpwnam($user))[2])
    {
        $uids[$i] = $uid;
    }
    else
    {
        $uids[$i] = '';
    }
}

# Loop forever:

while (1)
{
    for ( $i = 0; $i <= $#files; $i++ )
    {
        $monfile = $files[$i];
        $tagfile = "$monfile.$self";
        $userid = $uids[$i];

        # Check for changes in the file to monitor:

        if (-f "$path/$tagfile")
        {
            if (-f "$path/$monfile")
            {
                $tag = '';
                unless (open(TAGFILE, "<$path/$tagfile"))
                {
                    warn "$self: can't read file '$path/$tagfile': $!\n";
                    next;
                }
                while (<TAGFILE>)
                {
                    chop;
                    if (/^\d+$/)
                    {
                        $tag = $_;
                        last;
                    }
                }
                close(TAGFILE);
                if ($tag eq '')
                {
                    warn "$self: wrong contents in file '$path/$tagfile'!\n";
                    next;
                }
                $len = -s "$path/$monfile";
                if ($len != $tag)
                {
                    &update;
                    if ($len > $tag)
                    {
                        $text = "$self: new preport in folder '$monfile'!";
                        &notify;
                    }
#                   else
#                   {
#                       $text = "$self: file '$monfile' waned!";
#                       &notify;
#                   }
                }
#               else
#               {
#                   $text = "$self: file '$monfile' didn't change.";
#                   &notify;
#               }
            }
            else
            {
                unlink("$path/$tagfile");
                $text = "$self: file '$monfile' disappeared!";
                &notify;
            }
        }
        else
        {
            if (-f "$path/$monfile")
            {
                $len = -s "$path/$monfile";
                &update;
#               $text = "$self: new file '$monfile'!";
#               &notify;
            }
            else
            {
                $text = "$self: no file '$monfile'!";
                &notify;
            }
        }
    }
    sleep(5);
}

exit 0;

sub update
{
    unless (open(TAGFILE, ">$path/$tagfile"))
    {
        warn "$self: can't write file '$path/$tagfile': $!\n";
        return;
    }
    print TAGFILE "$len\n";
    close(TAGFILE);
}

sub notify
{
    # Read in all the devices currently used by the system, determine
    # the terminals the user is connected to and send a message to it:

    unless (opendir(DEV, "/dev"))
    {
        warn "$self: can't read directory '/dev': $!\n";
        return;
    }
    while ($terminal = readdir(DEV))
    {
        next if ($terminal eq '.');
        next if ($terminal eq '..');
        next unless ($terminal =~ /^tty/i);
        next unless (($uid) = (stat("/dev/$terminal"))[4]);
        if ($uid == $userid)
        {
            if (open(TEXT, ">/dev/$terminal"))
            {
                print TEXT "\n\n\n$text\n\n\n";
                close(TEXT);
            }
        }
    }
    closedir(DEV);
}

__END__