1. Querying Directory Contents Copyright © The University of Edinburgh 2011 This work is licensed under the Creative Commons Attribution License See http://software-carpentry.org/license.html for more information. Python

2. Querying Directory Contents We know how to move around directories

3. PythonQuerying Directory Contents We know how to move around directories And how to list what’s in directories

4. PythonQuerying Directory Contents We know how to move around directories And how to list what’s in directories How do we

5. PythonQuerying Directory Contents We know how to move around directories And how to list what’s in directories How do we –Check whether a file exists

6. PythonQuerying Directory Contents We know how to move around directories And how to list what’s in directories How do we –Check whether a file exists –Tell apart a file and a directory

7. PythonQuerying Directory Contents We know how to move around directories And how to list what’s in directories How do we –Check whether a file exists –Tell apart a file and a directory –See if two variables refer to the same directory

8. PythonQuerying Directory Contents We know how to move around directories And how to list what’s in directories How do we –Check whether a file exists –Tell apart a file and a directory –See if two variables refer to the same directory – Check that we are allowed to delete a file

9. PythonQuerying Directory Contents We know how to move around directories And how to list what’s in directories How do we –Check whether a file exists –Tell apart a file and a directory –See if two variables refer to the same directory – Check that we are allowed to delete a file – Get the size of a file

10. PythonQuerying Directory Contents >>> from os import exists pizza.cfg notes.txt solar vladusers

11. PythonQuerying Directory Contents >>> from os import exists >>> exists('pizza.cfg') pizza.cfg notes.txt solar vladusers

12. PythonQuerying Directory Contents >>> from os import exists >>> exists('pizza.cfg') True pizza.cfg notes.txt solar vladusers

13. PythonQuerying Directory Contents >>> from os import exists >>> exists('pizza.cfg') True >>> exists('/users/vlad/pizza.cfg') pizza.cfg notes.txt solar vladusers

14. PythonQuerying Directory Contents >>> from os import exists >>> exists('pizza.cfg') True >>> exists('/users/vlad/pizza.cfg') True pizza.cfg notes.txt solar vladusers

15. PythonQuerying Directory Contents >>> from os import exists >>> exists('pizza.cfg') True >>> exists('/users/vlad/pizza.cfg') True >>> exists('solar') pizza.cfg notes.txt solar vladusers

16. PythonQuerying Directory Contents >>> from os import exists >>> exists('pizza.cfg') True >>> exists('/users/vlad/pizza.cfg') True >>> exists('solar') True pizza.cfg notes.txt solar vladusers

17. PythonQuerying Directory Contents >>> from os import exists >>> exists('pizza.cfg') True >>> exists('/users/vlad/pizza.cfg') True >>> exists('solar') True >>> exists('/users/vlad/solar') pizza.cfg notes.txt solar vladusers

18. PythonQuerying Directory Contents >>> from os import exists >>> exists('pizza.cfg') True >>> exists('/users/vlad/pizza.cfg') True >>> exists('solar') True >>> exists('/users/vlad/solar') True pizza.cfg notes.txt solar vladusers

19. PythonQuerying Directory Contents >>> from os import exists >>> exists('pizza.cfg') True >>> exists('/users/vlad/pizza.cfg') True >>> exists('solar') True >>> exists('/users/vlad/solar') True >>> exists('no-such-file') pizza.cfg notes.txt solar vladusers

20. PythonQuerying Directory Contents >>> from os import exists >>> exists('pizza.cfg') True >>> exists('/users/vlad/pizza.cfg') True >>> exists('solar') True >>> exists('/users/vlad/solar') True >>> exists('no-such-file') False pizza.cfg notes.txt solar vladusers

21. PythonQuerying Directory Contents >>> from os import exists >>> exists('pizza.cfg') True >>> exists('/users/vlad/pizza.cfg') True >>> exists('solar') True >>> exists('/users/vlad/solar') True >>> exists('no-such-file') False >>> exists('/users/vlad/no-such-thing') pizza.cfg notes.txt solar vladusers

22. PythonQuerying Directory Contents >>> from os import exists >>> exists('pizza.cfg') True >>> exists('/users/vlad/pizza.cfg') True >>> exists('solar') True >>> exists('/users/vlad/solar') True >>> exists('no-such-file') False >>> exists('/users/vlad/no-such-thing') False pizza.cfg notes.txt solar vladusers

23. PythonQuerying Directory Contents >>> from os import isfile, isdir pizza.cfg notes.txt solar vladusers

24. PythonQuerying Directory Contents >>> from os import isfile, isdir >>> isfile('pizza.cfg') pizza.cfg notes.txt solar vladusers

25. PythonQuerying Directory Contents >>> from os import isfile, isdir >>> isfile('pizza.cfg') True pizza.cfg notes.txt solar vladusers

26. PythonQuerying Directory Contents >>> from os import isfile, isdir >>> isfile('pizza.cfg') True >>> isfile('solar') pizza.cfg notes.txt solar vladusers

27. PythonQuerying Directory Contents >>> from os import isfile, isdir >>> isfile('pizza.cfg') True >>> isfile('solar') False pizza.cfg notes.txt solar vladusers

28. PythonQuerying Directory Contents >>> from os import isfile, isdir >>> isfile('pizza.cfg') True >>> isfile('solar') False >>> isfile('no-such-file') pizza.cfg notes.txt solar vladusers

29. PythonQuerying Directory Contents >>> from os import isfile, isdir >>> isfile('pizza.cfg') True >>> isfile('solar') False >>> isfile('no-such-file') False pizza.cfg notes.txt solar vladusers

30. PythonQuerying Directory Contents >>> from os import isfile, isdir >>> isfile('pizza.cfg') True >>> isfile('solar') False >>> isfile('no-such-file') False >>> isdir('solar') pizza.cfg notes.txt solar vladusers

31. PythonQuerying Directory Contents >>> from os import isfile, isdir >>> isfile('pizza.cfg') True >>> isfile('solar') False >>> isfile('no-such-file') False >>> isdir('solar') True pizza.cfg notes.txt solar vladusers

32. PythonQuerying Directory Contents >>> from os import isfile, isdir >>> isfile('pizza.cfg') True >>> isfile('solar') False >>> isfile('no-such-file') False >>> isdir('solar') True >>> isdir('pizza.cfg') pizza.cfg notes.txt solar vladusers

33. PythonQuerying Directory Contents >>> from os import isfile, isdir >>> isfile('pizza.cfg') True >>> isfile('solar') False >>> isfile('no-such-file') False >>> isdir('solar') True >>> isdir('pizza.cfg') False pizza.cfg notes.txt solar vladusers

34. PythonQuerying Directory Contents >>> from os import isfile, isdir >>> isfile('pizza.cfg') True >>> isfile('solar') False >>> isfile('no-such-file') False >>> isdir('solar') True >>> isdir('pizza.cfg') False >>> isdir('no-such-dir') pizza.cfg notes.txt solar vladusers

35. PythonQuerying Directory Contents >>> from os import isfile, isdir >>> isfile('pizza.cfg') True >>> isfile('solar') False >>> isfile('no-such-file') False >>> isdir('solar') True >>> isdir('pizza.cfg') False >>> isdir('no-such-dir') False pizza.cfg notes.txt solar vladusers

36. PythonQuerying Directory Contents >>> def check(path):... if isfile(path):... print "It's a file"... elif isdir(path):... print "It's a directory"... else:... print "It doesn't exist"...

37. PythonQuerying Directory Contents >>> def check(path):... if isfile(path):... print "It's a file"... elif isdir(path):... print "It's a directory"... else:... print "It doesn't exist"...

38. PythonQuerying Directory Contents >>> def check(path):... if isfile(path):... print "It's a file"... elif isdir(path):... print "It's a directory"... else:... print "It doesn't exist"...

39. PythonQuerying Directory Contents >>> def check(path):... if isfile(path):... print "It's a file"... elif isdir(path):... print "It's a directory"... else:... print "It doesn't exist"...

40. PythonQuerying Directory Contents >>> def check(path):... if isfile(path):... print "It's a file"... elif isdir(path):... print "It's a directory"... else:... print "It doesn't exist"... >>> check('/users/vlad/pizza.cfg') pizza.cfg notes.txt solar vladusers

41. PythonQuerying Directory Contents >>> def check(path):... if isfile(path):... print "It's a file"... elif isdir(path):... print "It's a directory"... else:... print "It doesn't exist"... >>> check('/users/vlad/pizza.cfg') It's a file pizza.cfg notes.txt solar vladusers

42. PythonQuerying Directory Contents >>> def check(path):... if isfile(path):... print "It's a file"... elif isdir(path):... print "It's a directory"... else:... print "It doesn't exist"... >>> check('/users/vlad/pizza.cfg') It's a file >>> check('/users/vlad/solar') pizza.cfg notes.txt solar vladusers

43. PythonQuerying Directory Contents >>> def check(path):... if isfile(path):... print "It's a file"... elif isdir(path):... print "It's a directory"... else:... print "It doesn't exist"... >>> check('/users/vlad/pizza.cfg') It's a file >>> check('/users/vlad/solar') It's a directory pizza.cfg notes.txt solar vladusers

44. PythonQuerying Directory Contents >>> def check(path):... if isfile(path):... print "It's a file"... elif isdir(path):... print "It's a directory"... else:... print "It doesn't exist"... >>> check('/users/vlad/pizza.cfg') It's a file >>> check('/users/vlad/solar') It's a directory >>> check('/users/vlad/no-such-file') pizza.cfg notes.txt solar vladusers

45. PythonQuerying Directory Contents >>> def check(path):... if isfile(path):... print "It's a file"... elif isdir(path):... print "It's a directory"... else:... print "It doesn't exist"... >>> check('/users/vlad/pizza.cfg') It's a file >>> check('/users/vlad/solar') It's a directory >>> check('/users/vlad/no-such-file') It doesn't exist pizza.cfg notes.txt solar vladusers

46. PythonQuerying Directory Contents >>> from os.path import samefile pizza.cfg notes.txt solar vladusers

47. PythonQuerying Directory Contents >>> from os.path import samefile >>> file1 = 'pizza.cfg' >>> file2 = '/users/vlad/pizza.cfg' >>> file3 = 'notes.txt' pizza.cfg notes.txt solar vladusers file3file1file2

48. PythonQuerying Directory Contents >>> from os.path import samefile >>> file1 = 'pizza.cfg' >>> file2 = '/users/vlad/pizza.cfg' >>> file3 = 'notes.txt' >>> samefile(file1, file2) pizza.cfg notes.txt solar vladusers file1file2file3

49. PythonQuerying Directory Contents >>> from os.path import samefile >>> file1 = 'pizza.cfg' >>> file2 = '/users/vlad/pizza.cfg' >>> file3 = 'notes.txt' >>> samefile(file1, file2) True pizza.cfg notes.txt solar vladusers file3file1file2

50. PythonQuerying Directory Contents >>> from os.path import samefile >>> file1 = 'pizza.cfg' >>> file2 = '/users/vlad/pizza.cfg' >>> file3 = 'notes.txt' >>> samefile(file1, file2) True >>> samefile(file1, file3) pizza.cfg notes.txt solar vladusers file3file1file2

51. PythonQuerying Directory Contents >>> from os.path import samefile >>> file1 = 'pizza.cfg' >>> file2 = '/users/vlad/pizza.cfg' >>> file3 = 'notes.txt' >>> samefile(file1, file2) True >>> samefile(file1, file3) False pizza.cfg notes.txt solar vladusers file2file3file1

52. PythonQuerying Directory Contents >>> from os import access

53. PythonQuerying Directory Contents >>> from os import access >>> from os import F_OK, R_OK, W_OK, X_OK

54. PythonQuerying Directory Contents >>> from os import access >>> from os import F_OK, R_OK, W_OK, X_OK >>> access('pizza.cfg', F_OK) Does the path exist?

55. PythonQuerying Directory Contents >>> from os import access >>> from os import F_OK, R_OK, W_OK, X_OK >>> access('pizza.cfg', F_OK) True Does the path exist?

56. PythonQuerying Directory Contents >>> from os import access >>> from os import F_OK, R_OK, W_OK, X_OK >>> access('pizza.cfg', F_OK) True >>> access('pizza.cfg', R_OK) Can it be read?

57. PythonQuerying Directory Contents >>> from os import access >>> from os import F_OK, R_OK, W_OK, X_OK >>> access('pizza.cfg', F_OK) True >>> access('pizza.cfg', R_OK) True Can it be read?

58. PythonQuerying Directory Contents >>> from os import access >>> from os import F_OK, R_OK, W_OK, X_OK >>> access('pizza.cfg', F_OK) True >>> access('pizza.cfg', R_OK) True >>> access('pizza.cfg', W_OK) Can it be written?

59. PythonQuerying Directory Contents >>> from os import access >>> from os import F_OK, R_OK, W_OK, X_OK >>> access('pizza.cfg', F_OK) True >>> access('pizza.cfg', R_OK) True >>> access('pizza.cfg', W_OK) True Can it be written?

60. PythonQuerying Directory Contents >>> from os import access >>> from os import F_OK, R_OK, W_OK, X_OK >>> access('pizza.cfg', F_OK) True >>> access('pizza.cfg', R_OK) True >>> access('pizza.cfg', W_OK) True >>> access('pizza.cfg', X_OK) Can it be executed?

61. PythonQuerying Directory Contents >>> from os import access >>> from os import F_OK, R_OK, W_OK, X_OK >>> access('pizza.cfg', F_OK) True >>> access('pizza.cfg', R_OK) True >>> access('pizza.cfg', W_OK) True >>> access('pizza.cfg', X_OK) False Can it be executed?

62. PythonQuerying Directory Contents >>> from os import access >>> from os import F_OK, R_OK, W_OK, X_OK >>> access('pizza.cfg', F_OK) True >>> access('pizza.cfg', R_OK) True >>> access('pizza.cfg', W_OK) True >>> access('pizza.cfg', X_OK) False >>> access('pizza.cfg', os.R_OK | os.W_OK)

63. PythonQuerying Directory Contents >>> from os import access >>> from os import F_OK, R_OK, W_OK, X_OK >>> access('pizza.cfg', F_OK) True >>> access('pizza.cfg', R_OK) True >>> access('pizza.cfg', W_OK) True >>> access('pizza.cfg', X_OK) False >>> access('pizza.cfg', os.R_OK | os.W_OK) True

64. PythonQuerying Directory Contents >>> from os import access >>> from os import F_OK, R_OK, W_OK, X_OK >>> access('pizza.cfg', F_OK) True >>> access('pizza.cfg', R_OK) True >>> access('pizza.cfg', W_OK) True >>> access('pizza.cfg', X_OK) False >>> access('pizza.cfg', os.R_OK | os.W_OK) True >>> access('pizza.cfg', os.R_OK | os.X_OK)

65. PythonQuerying Directory Contents >>> from os import access >>> from os import F_OK, R_OK, W_OK, X_OK >>> access('pizza.cfg', F_OK) True >>> access('pizza.cfg', R_OK) True >>> access('pizza.cfg', W_OK) True >>> access('pizza.cfg', X_OK) False >>> access('pizza.cfg', os.R_OK | os.W_OK) True >>> access('pizza.cfg', os.R_OK | os.X_OK) False

66. PythonQuerying Directory Contents >>> from os import access >>> from os import F_OK, R_OK, W_OK, X_OK >>> access('pizza.cfg', F_OK) True >>> access('pizza.cfg', R_OK) True >>> access('pizza.cfg', W_OK) True >>> access('pizza.cfg', X_OK) False >>> access('pizza.cfg', os.R_OK | os.W_OK) True >>> access('pizza.cfg', os.R_OK | os.X_OK) False >>> access('pizza.cfg', os.F_OK | os.R_OK | os.W_OK)

67. PythonQuerying Directory Contents >>> from os import access >>> from os import F_OK, R_OK, W_OK, X_OK >>> access('pizza.cfg', F_OK) True >>> access('pizza.cfg', R_OK) True >>> access('pizza.cfg', W_OK) True >>> access('pizza.cfg', X_OK) False >>> access('pizza.cfg', os.R_OK | os.W_OK) True >>> access('pizza.cfg', os.R_OK | os.X_OK) False >>> access('pizza.cfg', os.F_OK | os.R_OK | os.W_OK) True

68. PythonQuerying Directory Contents >>> from os import stat >>> info = stat('pizza.cfg')

69. PythonQuerying Directory Contents >>> from os import stat >>> info = stat('pizza.cfg') >>> print info (33188, 5557L, 73188003L, 1, 3946, 4000, 8172L, 1304999431, 1304951325, 1304951325) stat returns a record

70. PythonQuerying Directory Contents >>> from os import stat >>> info = stat('pizza.cfg') >>> print info (33188, 5557L, 73188003L, 1, 3946, 4000, 8172L, 1304999431, 1304951325, 1304951325) >>> print info.st_mode 33188 Protection bits

71. PythonQuerying Directory Contents >>> from os import stat >>> info = stat('pizza.cfg') >>> print info (33188, 5557L, 73188003L, 1, 3946, 4000, 8172L, 1304999431, 1304951325, 1304951325) >>> print info.st_mode 33188 >>> print info.st_ino 5557 Inode number

72. PythonQuerying Directory Contents >>> from os import stat >>> info = stat('pizza.cfg') >>> print info (33188, 5557L, 73188003L, 1, 3946, 4000, 8172L, 1304999431, 1304951325, 1304951325) >>> print info.st_mode 33188 >>> print info.st_ino 5557 >>> print info.st_dev 73188003 Device

73. PythonQuerying Directory Contents >>> from os import stat >>> info = stat('pizza.cfg') >>> print info (33188, 5557L, 73188003L, 1, 3946, 4000, 8172L, 1304999431, 1304951325, 1304951325) >>> print info.st_mode 33188 >>> print info.st_ino 5557 >>> print info.st_dev 73188003 >>> print info.st_nlink 1 Number of hard links

74. PythonQuerying Directory Contents >>> from os import stat >>> info = stat('pizza.cfg') >>> print info (33188, 5557L, 73188003L, 1, 3946, 4000, 8172L, 1304999431, 1304951325, 1304951325) >>> print info.st_mode 33188 >>> print info.st_ino 5557 >>> print info.st_dev 73188003 >>> print info.st_nlink 1 >>> print info.st_uid 3946 Owner’s user ID

75. PythonQuerying Directory Contents >>> print info.st_gid 4000 Owner’s group ID

76. PythonQuerying Directory Contents >>> print info.st_gid 4000 >>> print info.st_size 8172 File size in bytes

77. PythonQuerying Directory Contents >>> print info.st_gid 4000 >>> print info.st_size 8172 >>> print info.st_atime 1304999431 Most recent access time

78. PythonQuerying Directory Contents >>> print info.st_gid 4000 >>> print info.st_size 8172 >>> print info.st_atime 1304999431 >>> print info.st_mtime 1304951325 Most recent modification

79. PythonQuerying Directory Contents >>> print info.st_gid 4000 >>> print info.st_size 8172 >>> print info.st_atime 1304999431 >>> print info.st_mtime 1304951325 >>> print info.st_ctime 1304951325 Most recent metadata change time for Linux or, creation time for Windows

80. PythonQuerying Directory Contents >>> print info.st_gid 4000 >>> print info.st_size 8172 >>> print info.st_atime 1304999431 >>> print info.st_mtime 1304951325 >>> print info.st_ctime 1304951325 >>> from os import stat_float_times >>> stat_float_times() False Owner’s group ID File size in bytes Most recent access time Most recent modification Most recent metadata change time for Linux or, creation time for Windows

81. PythonQuerying Directory Contents A stat record may contain operating system-specific values

82. PythonQuerying Directory Contents >>> print info.st_blocks 17 A stat record may contain operating system-specific values Number of blocks, for Linux

83. PythonQuerying Directory Contents >>> print info.st_blocks 17 >>> print info.st_blksize 8192 A stat record may contain operating system-specific values File system block size for Linux

84. PythonQuerying Directory Contents os.path Common pathname manipulations exists Does the given path exist? isfile Is the given path a file? isdir Is the given path a directory? samefile Are the given arguments paths to the same file or directory? os Miscellaneous operating system interfaces access Can the file/directory be accessed? statGet operating system-specific information

85. May 2011 created by Mike Jackson and Greg Wilson Copyright © Software Carpentry and The University of Edinburgh 2010-2011 This work is licensed under the Creative Commons Attribution License See http://software-carpentry.org/license.html for more information.