/usr/bin/esdcompat is in pulseaudio-esound-compat 1:4.0-0ubuntu11.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 | #!/bin/sh
# This file is part of PulseAudio.
#
# PulseAudio is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# PulseAudio is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with PulseAudio; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
# USA.
VERSION_STRING="pulseaudio esd wrapper 4.0"
fail() {
    echo "ERROR: $1"
    exit 1
}
PULSEAUDIO_SYSTEM_START=0
test -f /etc/default/pulseaudio && . /etc/default/pulseaudio
if [ ! $PULSEAUDIO_SYSTEM_START -eq 0 ]; then
	exit 0
fi
ARGS=" --log-target=syslog"
while [ "$#" -gt "0" ]; do
    case "$1" in
        "")
            ;;
        -v|--version)
            echo "$VERSION_STRING"
            exit 0
            ;;
        -h|--help)
            cat <<EOF
$VERSION_STRING
Usage: $0 [options]
  -v --version  print version information
  -h --help     show this help
Ignored directives:
  -tcp          use tcp/ip sockets in addition to unix domain
  -promiscuous  don't require authentication
  -d DEVICE     force esd to use sound device DEVICE
  -b            run server in 8 bit sound mode
  -r RATE       run server at sample rate of RATE
  -as SECS      free audio device after SECS of inactivity
  -unix         use unix domain sockets instead of tcp/ip
  -public       make tcp/ip access public (other than localhost)
  -terminate    terminate esd daemone after last client exits
  -nobeeps      disable startup beeps
  -trust        start esd even if use of /tmp/.esd can be insecure
  -port PORT    listen for connections at PORT (only for tcp/ip)
  -bind ADDRESS binds to ADDRESS (only for tcp/ip)
EOF
            exit 0
            ;;
        -spawnpid)
            shift
            ARGS="$ARGS '-Lmodule-esound-compat-spawnpid pid=$1'"
            ;;
        -spawnfd)
            shift
            ARGS="$ARGS '-Lmodule-esound-compat-spawnfd fd=$1'"
            ;;
        
        -unix|-b|-public|-terminate|-nobeeps|-trust|-tcp|-promiscuous)  
            # Ignore these commands
            ;; 
        -d|-r|-as|-port|-bind)
            # Ignore these commands and their arguments
            shift
            ;;
        *)
            fail "Unknown command: $1"
            ;;
    esac
    shift
done
eval "exec '/usr/bin/pulseaudio'$ARGS"
 |