Type Python, Press Enter, What Happens? - PyDX 2015

The slides from my talk at PyDX

Transcript

1. Type Python, Press Enter, What Happens? Philip James (@phildini) PyDX 2015
2. Who am I? @phildini #typepython
3. paulproteus@vellum:~ $ @phildini #typepython
4. paulproteus@vellum:~ $ python @phildini #typepython
5. paulproteus@vellum:~ $ python Python 2.7.6 (default, Apr 11 2014, 22:59:56) [GCC 4.8.2] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> @phildini #typepython
6. paulproteus@vellum:~ $ python Python 2.7.6 (default, Apr 11 2014, 22:59:56) [GCC 4.8.2] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> @phildini #typepython 2+2
7. paulproteus@vellum:~ $ python Python 2.7.6 (default, Apr 11 2014, 22:59:56) [GCC 4.8.2] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> @phildini #typepython 2+2 4 >>>
8. paulproteus@vellum:~ $ python Python 2.7.6 (default, Apr 11 2014, 22:59:56) [GCC 4.8.2] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> @phildini #typepython 2+2 4 >>> KeyboardInterrupt >>>
9. paulproteus@vellum:~ $ python Python 2.7.6 (default, Apr 11 2014, 22:59:56) [GCC 4.8.2] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> @phildini #typepython 2+2 4 >>> KeyboardInterrupt >>> paulproteus@vellum:~ $
10. paulproteus@vellum:~ $ @phildini #typepython
11. paulproteus@vellum:~ $ python @phildini #typepython
12. paulproteus@vellum:~ $ @phildini #typepython
13. paulproteus@vellum:~ $ echo $PATH @phildini #typepython
14. paulproteus@vellum:~ $ echo $PATH /home/paulproteus/bin:/usr/bin:/usr/local/bin: @phildini #typepython
15. paulproteus@vellum:~ $ echo $PATH /home/paulproteus/bin:/usr/bin:/usr/local/bin: paulproteus@vellum:~ $ @phildini #typepython
16. paulproteus@vellum:~ $ echo $PATH /home/paulproteus/bin:/usr/bin:/usr/local/bin: paulproteus@vellum:~ $ python @phildini #typepython
17. paulproteus@vellum:~ $ echo $PATH /home/paulproteus/bin:/usr/bin:/usr/local/bin: paulproteus@vellum:~ $ python @phildini #typepython
18. paulproteus@vellum:~ $ echo $PATH /home/paulproteus/bin:/usr/bin:/usr/local/bin: paulproteus@vellum:~ $ python @phildini #typepython
19. paulproteus@vellum:~ $ echo $PATH /home/paulproteus/bin:/usr/bin:/usr/local/bin: paulproteus@vellum:~ $ python @phildini #typepython
20. paulproteus@vellum:~ $ @phildini #typepython
21. paulproteus@vellum:~ $ hexdump -C /usr/bin/python @phildini #typepython
22. paulproteus@vellum:~ $ hexdump -C /usr/bin/python 00000000 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 |.ELF............| 00000010 02 00 3e 00 01 00 00 00 55 49 57 00 00 00 00 00 |..>.....UIW.....| 00000020 40 00 00 00 00 00 00 00 08 15 33 00 00 00 00 00 |@.........3.....| 00000030 00 00 00 00 40 00 38 00 09 00 40 00 1c 00 1b 00 |....@.8...@.....| 00000040 06 00 00 00 05 00 00 00 40 00 00 00 00 00 00 00 |........@.......| 00000050 40 00 40 00 00 00 00 00 40 00 40 00 00 00 00 00 |@.@.....@.@.....| 00000060 f8 01 00 00 00 00 00 00 f8 01 00 00 00 00 00 00 |................| 00000070 08 00 00 00 00 00 00 00 03 00 00 00 04 00 00 00 |................| 00000080 38 02 00 00 00 00 00 00 38 02 40 00 00 00 00 00 |8.......8.@.....| 00000090 38 02 40 00 00 00 00 00 1c 00 00 00 00 00 00 00 |8.@.............| @phildini #typepython
23. paulproteus@vellum:~ $ @phildini #typepython
24. paulproteus@vellum:~ $ file /usr/bin/python @phildini #typepython
25. paulproteus@vellum:~ $ file /usr/bin/python /usr/bin/python: ELF 64-bit LSB executable @phildini #typepython
26. for dir in os.getenv( 'PATH').split(':'): try: os.stat(dir + '/python') return dir except: pass raise CommandNotFound() @phildini #typepython
27. bash pid: 1221 @phildini #typepython
28. bash pid: 1221 paulproteus@vellum:~ $ @phildini #typepython
29. bash pid: 1221 paulproteus@vellum:~ $ exec python @phildini #typepython
30. python pid: 1221 @phildini #typepython
31. python pid: 1221 @phildini #typepython
32. python pid: 1221 paulproteus@vellum:~ $ @phildini #typepython
33. python pid: 1221 paulproteus@vellum:~ $ [Process completed] @phildini #typepython
34. bash pid: 1221 @phildini #typepython
35. bash pid: 1221 fork() @phildini #typepython
36. bash pid: 1221 fork() bash pid: 1222 @phildini #typepython
37. bash pid: 1221 fork() bash pid: 1222 exec() @phildini #typepython
38. bash pid: 1221 fork() python pid: 1222 exec() @phildini #typepython
39. paulproteus@vellum:~ $ @phildini #typepython
40. paulproteus@vellum:~ $ pstree @phildini #typepython
41. paulproteus@vellum:~ $ pstree init─┬ ... ├─cron ... └─sshd─┬─bash───python └─bash───pstree @phildini #typepython
42. Process Creation 1. Find binary in $PATH 2. Fork 3. Exec @phildini #typepython
43. paulproteus@vellum:~ $ python -v @phildini #typepython
44. # installing zipimport hook import zipimport # builtin # installed zipimport hook # /usr/lib/python2.7/site.pyc matches /usr/lib/python2.7/site.py import site # precompiled from /usr/ lib/python2.7/site.pyc # /usr/lib/python2.7/os.pyc matches /usr/lib/python2.7/os.py paulproteus@vellum:~ $ python -v @phildini #typepython
45. bash pid: 1221 fork() python pid: 1222 exec( ‘/usr/bin/python’, [‘python’, ‘-v’] ) @phildini #typepython
46. bash pid: 1221 fork() python pid: 1222 argv = [‘python’, ‘-v’] exec( ‘/usr/bin/python’, [‘python’, ‘-v’] ) @phildini #typepython
47. python pid: 1222 argv = [‘python’] @phildini #typepython
48. Python 2.7.6 (default, Apr 11 2014, 22:59:56) [GCC 4.8.2] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> @phildini #typepython
50. /dev/pts/3
51. python pid: 1222 0: /dev/pts/3 @phildini #typepython
52. python pid: 1222 0: /dev/pts/3 stdin @phildini #typepython
53. python pid: 1222 0: /dev/pts/3 2 @phildini #typepython
54. python pid: 1222 0: /dev/pts/3 termios 2 @phildini #typepython
55. python pid: 1222 0: /dev/pts/3 termios 2 @phildini #typepython
56. paulproteus@vellum:~ $ @phildini #typepython
57. paulproteus@vellum:~ $ strace python @phildini #typepython
58. paulproteus@vellum:~ $ strace python [...] read(0, @phildini #typepython
59. paulproteus@vellum:~ $ strace python [...] read(0, 2 @phildini #typepython
60. paulproteus@vellum:~ $ strace python [...] read(0, “2”, 1) 2 @phildini #typepython
61. paulproteus@vellum:~ $ strace python [...] read(0, “2”, 1) read(0, 2 @phildini #typepython
62. paulproteus@vellum:~ $ strace python [...] read(0, “2”, 1) read(0, 2 + @phildini #typepython
63. paulproteus@vellum:~ $ strace python [...] read(0, “2”, 1) read(0, “+”, 1) 2 + @phildini #typepython
64. paulproteus@vellum:~ $ strace python [...] read(0, “2”, 1) read(0, “+”, 1) read(0, “2”, 1) read(0, “\n”, 1) 2 + 2 Enter @phildini #typepython
65. while True: line = ‘’ chr = sys.stdin.read(1) line += chr if chr == ‘\n’: print eval(line) @phildini #typepython
66. while True: line = ‘’ chr = sys.stdin.read(1) line += chr if chr == ‘\n’: print eval(line) @phildini #typepython
67. python pid: 1222 0: /dev/pts/3 1: /dev/pts/3 2: /dev/pts/3 @phildini #typepython
68. bash pid: 1221 python pid: 1222 0: /dev/pts/3 1: /dev/pts/3 2: /dev/pts/3 0: /dev/pts/3 1: /dev/pts/3 2: /dev/pts/3 @phildini #typepython
69. bash pid: 1221 python pid: 1222 0: /dev/pts/3 1: /dev/pts/3 2: /dev/pts/3 0: /dev/pts/3 1: /dev/pts/3 2: /dev/pts/3 foreground @phildini #typepython
70. Ctrl C @phildini #typepython
71. Ctrl C termios @phildini #typepython
72. sigint Ctrl C termios @phildini #typepython
73. python pid: 1222 sigint Ctrl C termios @phildini #typepython
74. >>> @phildini #typepython
75. >>> Crtl C @phildini #typepython
76. >>> Crtl C KeyboardInterrupt >>> @phildini #typepython
77. python pid: 1222 sigint @phildini #typepython
78. python pid: 1222 sigint sig pipe @phildini #typepython
79. cat pid: 1222 0: /dev/pts/3 Ctrl D termios @phildini #typepython
80. cat pid: 1222 0: /dev/pts/3 Ctrl D termios @phildini #typepython
81. python pid: 1222 0: /dev/pts/3 Ctrl D termios @phildini #typepython
82. >>> import sys >>> sys.exit() @phildini #typepython
83. >>> raise SystemExit() @phildini #typepython
84. paulproteus@vellum:~ $ strace python @phildini #typepython
85. paulproteus@vellum:~ $ strace python [...] exit(0 <no return …> @phildini #typepython
86. paulproteus@vellum:~ $ strace python [...] exit(0 <no return …> paulproteus@vellum:~ $ @phildini #typepython
87. paulproteus@vellum:~ $ strace python [...] exit(0 <no return …> paulproteus@vellum:~ $ echo $? @phildini #typepython
88. paulproteus@vellum:~ $ strace python [...] exit(0 <no return …> paulproteus@vellum:~ $ echo $? 0 @phildini #typepython
89. >>> import sys >>> sys.exit(1) @phildini #typepython
90. >>> import sys >>> sys.exit(1) paulproteus@vellum:~ $ echo $? 1 @phildini #typepython
91. bash pid: 1221 @phildini #typepython
92. python pid: 1222 argv = [‘python’] bash pid: 1221 @phildini #typepython
93. python pid: 1222 argv = [‘python’] 0: /dev/pts/3 1: /dev/pts/3 2: /dev/pts/3 bash pid: 1221 @phildini #typepython
94. python pid: 1222 argv = [‘python’] sigint sig pipe 0: /dev/pts/3 1: /dev/pts/3 2: /dev/pts/3 bash pid: 1221 @phildini #typepython
95. Be Curious! • pstree • strace • file/hexdump @phildini #typepython
96. Questions? Thanks! Philip James (@phildini) @phildini #typepython