example_output.txt

$ strace-process-tree zdaemon-py3.GIT/TRACE3
6184 execve("bin/test", ["bin/test", "-pvc", "-t", "README"], [/* 65 vars */])
  ├─6196 execve("/bin/sh", ["/bin/sh", "-c", "./zdaemon -p 'echo hello world' "...], [/* 67 vars */])           
  │   └─6197 execve("./zdaemon", ["./zdaemon", "-p", "echo hello world", "fg"], [/* 67 vars */])
  │       └─6199 execve("/bin/echo", ["echo", "hello", "world"], [/* 67 vars */])
  ├─6200 execve("/bin/sh", ["/bin/sh", "-c", "./zdaemon -p 'sleep 100' start"], [/* 67 vars */])           
  │   └─6201 execve("./zdaemon", ["./zdaemon", "-p", "sleep 100", "start"], [/* 67 vars */])
  │       └─6205 execve("/usr/bin/python3.3", ["/usr/bin/python3.3", "./zdaemon", "-S", "schema.xml", "-b", "10", "-s", "zdsock", "-m", "0o22", "-x", "0,2", "sleep", "100"], [/* 68 vars */])           
  │           └─6212 clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f163fcab9d0)
  │               ├─6213 clone(child_stack=0x7f163e4b4ff0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7f163e4b59d0, tls=0x7f163e4b5700, child_tidptr=0x7f163e4b59d0)
  │               └─6214 execve("/bin/sleep", ["sleep", "100"], [/* 67 vars */])
  ├─6215 execve("/bin/sh", ["/bin/sh", "-c", "./zdaemon -p 'sleep 100' status"], [/* 67 vars */])           
  │   └─6216 execve("./zdaemon", ["./zdaemon", "-p", "sleep 100", "status"], [/* 67 vars */])
  ├─6217 execve("/bin/sh", ["/bin/sh", "-c", "./zdaemon -p 'sleep 100' stop"], [/* 67 vars */])           
  │   └─6218 execve("./zdaemon", ["./zdaemon", "-p", "sleep 100", "stop"], [/* 67 vars */])
  ├─6220 execve("/bin/sh", ["/bin/sh", "-c", "./zdaemon -p 'sleep 100' status"], [/* 67 vars */])           
  │   └─6221 execve("./zdaemon", ["./zdaemon", "-p", "sleep 100", "status"], [/* 67 vars */])
  ├─6225 execve("/bin/sh", ["/bin/sh", "-c", "./zdaemon -Cconf start"], [/* 67 vars */])           
  │   └─6226 execve("./zdaemon", ["./zdaemon", "-Cconf", "start"], [/* 67 vars */])
  │       └─6253 execve("/usr/bin/python3.3", ["/usr/bin/python3.3", "./zdaemon", "-S", "/home/mg/src/zdaemon-py3.GIT/src"..., "-C", "conf", "sleep", "100"], [/* 68 vars */])           
  │           └─6262 clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7fd2a97bf9d0)
  │               ├─6263 clone(child_stack=0x7fd2a7fc8ff0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7fd2a7fc99d0, tls=0x7fd2a7fc9700, child_tidptr=0x7fd2a7fc99d0)
  │               └─6264 execve("/bin/sleep", ["sleep", "100"], [/* 67 vars */])
  ├─6269 execve("/bin/sh", ["/bin/sh", "-c", "ls"], [/* 67 vars */])           
  │   └─6270 execve("/bin/ls", ["ls"], [/* 67 vars */])
  ├─6271 execve("/bin/sh", ["/bin/sh", "-c", "./zdaemon -Cconf stop"], [/* 67 vars */])           
  │   └─6272 execve("./zdaemon", ["./zdaemon", "-Cconf", "stop"], [/* 67 vars */])
  ├─6278 execve("/bin/sh", ["/bin/sh", "-c", "./zdaemon -Cconf start"], [/* 67 vars */])           
  │   └─6279 execve("./zdaemon", ["./zdaemon", "-Cconf", "start"], [/* 67 vars */])
  │       └─6288 execve("/usr/bin/python3.3", ["/usr/bin/python3.3", "./zdaemon", "-S", "/home/mg/src/zdaemon-py3.GIT/src"..., "-C", "conf", "sleep", "100"], [/* 68 vars */])           
  │           └─6294 clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f44cb0e79d0)
  │               ├─6295 clone(child_stack=0x7f44c98f0ff0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7f44c98f19d0, tls=0x7f44c98f1700, child_tidptr=0x7f44c98f19d0)
  │               └─6296 execve("/bin/sleep", ["sleep", "100"], [/* 67 vars */])
  ├─6298 execve("/bin/sh", ["/bin/sh", "-c", "ls"], [/* 67 vars */])           
  │   └─6300 execve("/bin/ls", ["ls"], [/* 67 vars */])
  ├─6301 execve("/bin/sh", ["/bin/sh", "-c", "./zdaemon -Cconf stop"], [/* 67 vars */])           
  │   └─6302 execve("./zdaemon", ["./zdaemon", "-Cconf", "stop"], [/* 67 vars */])
  ├─6304 execve("/bin/sh", ["/bin/sh", "-c", "./zdaemon -Cconf start 100"], [/* 67 vars */])           
  │   └─6305 execve("./zdaemon", ["./zdaemon", "-Cconf", "start", "100"], [/* 67 vars */])
  │       └─6314 execve("/usr/bin/python3.3", ["/usr/bin/python3.3", "./zdaemon", "-S", "/home/mg/src/zdaemon-py3.GIT/src"..., "-C", "conf", "sleep", "100"], [/* 68 vars */])           
  │           └─6322 clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7ff8f14959d0)
  │               ├─6323 clone(child_stack=0x7ff8efc9eff0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7ff8efc9f9d0, tls=0x7ff8efc9f700, child_tidptr=0x7ff8efc9f9d0)
  │               └─6324 execve("/bin/sleep", ["sleep", "100"], [/* 67 vars */])
  ├─6333 execve("/bin/sh", ["/bin/sh", "-c", "./zdaemon -Cconf status"], [/* 67 vars */])           
  │   └─6334 execve("./zdaemon", ["./zdaemon", "-Cconf", "status"], [/* 67 vars */])
  ├─6346 execve("/bin/sh", ["/bin/sh", "-c", "./zdaemon -Cconf stop"], [/* 67 vars */])           
  │   └─6347 execve("./zdaemon", ["./zdaemon", "-Cconf", "stop"], [/* 67 vars */])
  ├─6348 execve("/bin/sh", ["/bin/sh", "-c", "./zdaemon -Cconf fg"], [/* 67 vars */])           
  │   └─6349 execve("./zdaemon", ["./zdaemon", "-Cconf", "fg"], [/* 67 vars */])
  │       └─6350 execve("/usr/bin/env", ["env"], [/* 68 vars */])
  ├─6351 execve("/bin/sh", ["/bin/sh", "-c", "./zdaemon -Cconf start"], [/* 67 vars */])           
  │   └─6352 execve("./zdaemon", ["./zdaemon", "-Cconf", "start"], [/* 67 vars */])
  │       └─6354 execve("/usr/bin/python3.3", ["/usr/bin/python3.3", "./zdaemon", "-S", "/home/mg/src/zdaemon-py3.GIT/src"..., "-C", "conf", "tail", "-f", "data"], [/* 68 vars */])           
  │           └─6380 clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7fb4506119d0)
  │               ├─6381 clone(child_stack=0x7fb44ee1aff0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7fb44ee1b9d0, tls=0x7fb44ee1b700, child_tidptr=0x7fb44ee1b9d0)
  │               └─6382 execve("/usr/bin/tail", ["tail", "-f", "data"], [/* 67 vars */])
  └─6399 execve("/bin/sh", ["/bin/sh", "-c", "./zdaemon -Cconf reopen_transcri"...], [/* 67 vars */])           
      └─6400 execve("./zdaemon", ["./zdaemon", "-Cconf", "reopen_transcript"], [/* 67 vars */])

strace_process_tree.py

#!/usr/bin/python
# -*- coding: UTF-8 -*-
"""
Usage:
  strace-process-tree [filename]

Read strace -f output and produce a process tree.
"""

import re
import fileinput
from collections import defaultdict


__version__ = '0.2.2'
__author__ = 'Marius Gedminas <marius@gedmin.as>'
__url__ = 'https://gist.github.com/mgedmin/4953427'
__licence__ = 'GPL v2 or later' # or ask me for MIT


def events(stream):
    RESUMED_PREFIX = re.compile('<... \w+ resumed> ')
    UNFINISHED_SUFFIX = ' <unfinished ...>'
    pending = {}
    for line in stream:
        pid, spaces, event = line.rstrip().partition(' ')
        pid = int(pid)
        event = event.lstrip()
        m = RESUMED_PREFIX.match(event)
        if m is not None:
            event = pending.pop(pid) + event[len(m.group()):]
        if event.endswith(UNFINISHED_SUFFIX):
            pending[pid] = event[:-len(UNFINISHED_SUFFIX)]
        else:
            yield (pid, event)


class ProcessTree:
    def __init__(self):
        self.names = {}
        self.parents = {}
        self.children = defaultdict(list)
        self.roots = set()
        self.all = set()
        # invariant: self.roots == self.all - set(self.parents), probably

    def make_known(self, pid):
        if pid not in self.all:
            self.roots.add(pid)
            self.all.add(pid)

    def set_name(self, pid, name):
        self.make_known(pid)
        self.names[pid] = name

    def add_child(self, ppid, pid):
        self.make_known(ppid)
        self.make_known(pid)
        if pid in self.roots:
            self.roots.remove(pid)
        self.parents[pid] = ppid
        self.children[ppid].append(pid)

    def _format(self, pids, indent='', level=0):
        r = []
        for n, pid in enumerate(pids):
            if level == 0:
                s, cs = '', ''
            elif n < len(pids) - 1:
                s, cs = '  ├─', '  │ '
            else:
                s, cs = '  └─', '    '
            r.append(indent + s + '{} {}\n'.format(pid, self.names.get(pid, '')))
            r.append(self._format(sorted(self.children.get(pid, [])),
                                  indent+cs, level+1))

        return ''.join(r)

    def __str__(self):
        return self._format(sorted(self.roots))


def main():
    tree = ProcessTree()

    for pid, event in events(fileinput.input()):
        if event.startswith('execve('):
            args, equal, result = event.rpartition(' = ')
            if result == '0':
                tree.set_name(pid, args)
        if event.startswith('clone('):
            args, equal, result = event.rpartition(' = ')
            if result.isdigit():
                child_pid = int(result)
                tree.set_name(child_pid, args)
                tree.add_child(pid, child_pid)

    print(str(tree).rstrip())

if __name__ == '__main__':
    main()