pstree.sh

#!/bin/bash
#!/bin/sh

# pstree
# Copyright 2015-2018 Rivoreo
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

# Compatible with ash and bash; incompatible with ksh; untested with other shells.

ORIG_IFS="$IFS"

# Get the process list at once, otherwise this script will running very slowly
process_list="`ps -A -o pid= -o ppid=`"

find_children() {
	#printf "function: find_children $* (#=$#)\\n"
	if [ $# -lt 1 ]; then
		echo "Usage: find_children <pid> [<treeline>] [...]" 1>&2
		return 255
	fi
	#local level="$2"
	#[ -z "$level" ] && level=0
	#local i="$level"
	#while [ $i -gt 0 ]; do printf " "; i=$((i-1)); done
	local current_pid="$1"
	local current_ps_line
	current_ps_line="`ps -o pid= -o comm= -p \"$current_pid\"`" || return 1
	shift
	local i=0
	for c in "$@"; do
		i=$((i+1))
		[ "$c" = " " -a $i = $# ] && c=\\
		printf "   %c" "$c"
	done
	printf -- "-- "
	echo "$current_ps_line" | sed -r 's/^ +//'
	local children=
	i=0
	#printf %s\\n "$process_list" | while read pids; do
	IFS="
"
	for pids in $process_list; do
		#pid="`echo \"$pids\" | sed -r -e 's/ +[0-9]+$//' -e 's/^ *//'`"
		#ppid="`echo \"$pids\" | sed -r 's/^ *[0-9]+ +//'`"
		pid=
		ppid=
		IFS="$ORIG_IFS"
		for n in $pids; do
			[ -z "$pid" ] && pid=$n || ppid=$n
		done
		#echo "\"$pid\" \"$ppid\""
		[ "$ppid" = $$ -o "$pid" = $$ -o "$pid" = 0 ] && continue
		#[ "$ppid" = "$1" ] && find_children "$pid" $((level+1))
		#[ "$ppid" = "$current_pid" ] && find_children "$pid" "$@" "|"
		[ "$ppid" = "$current_pid" ] && children="$children
$pid" && i=$((i+1))
	done
	IFS="
"
	#echo "$children"
	for pid in $children; do
		i=$((i-1))
		if [ $i = 0 ]; then
			find_children $pid "$@" " "
		else
			find_children $pid "$@" "|"
		fi
	done
}

rootpid="$1"
[ -z "$rootpid" ] && rootpid=1
find_children "$rootpid"