#!/bin/sh
# Solaris style ptree

[ -x /usr/bin/ptree ] && exec /usr/bin/ptree "$@"

PATH=/bin:/usr/bin:/usr/sbin:/sbin
export PATH

case $1 in
-*)
 echo "
Usage: ptree [ PID | USER ]
Print process tree
 PID : extract branch for this process
 USER : filter for this (existing) user
 USER PID : do both
"
 exit
;;
*[!0-9]*)
 psopt="-u $1"
 shift
;;
*)
 psopt="-e"
esac
psopt="$psopt -H -o pid= -o args="

if [ -z "$1" ]; then
 ps $psopt
 exit
fi

#some effort to add less to the ps list
tmp=/tmp/ptree.$$
trap 'rm -f $tmp' 0 HUP INT TERM
ps $psopt >$tmp
<$tmp awk '
{ ci=index(substr($0,6),$2); o[ci]=$0 }
ci>s[a] { s[++a]=ci }
$1==pid {
 for(i=1;i<=a;i++) {
  si=s[i]; if(si<=ci) print o[si]
 }
 walkdown=ci
 next
}
ci<=walkdown { exit }
walkdown!=0 { print }
' pid="$1"

ptree $$