| 1 | #! /usr/bin/env python
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| 2 |
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| 3 | # Change the #! line occurring in Python scripts. The new interpreter
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| 4 | # pathname must be given with a -i option.
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| 5 | #
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| 6 | # Command line arguments are files or directories to be processed.
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| 7 | # Directories are searched recursively for files whose name looks
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| 8 | # like a python module.
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| 9 | # Symbolic links are always ignored (except as explicit directory
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| 10 | # arguments). Of course, the original file is kept as a back-up
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| 11 | # (with a "~" attached to its name).
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| 12 | #
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| 13 | # Undoubtedly you can do this using find and sed or perl, but this is
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| 14 | # a nice example of Python code that recurses down a directory tree
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| 15 | # and uses regular expressions. Also note several subtleties like
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| 16 | # preserving the file's mode and avoiding to even write a temp file
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| 17 | # when no changes are needed for a file.
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| 18 | #
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| 19 | # NB: by changing only the function fixfile() you can turn this
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| 20 | # into a program for a different change to Python programs...
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| 21 |
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| 22 | import sys
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| 23 | import re
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| 24 | import os
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| 25 | from stat import *
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| 26 | import getopt
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| 27 |
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| 28 | err = sys.stderr.write
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| 29 | dbg = err
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| 30 | rep = sys.stdout.write
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| 31 |
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| 32 | new_interpreter = None
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| 33 |
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| 34 | def main():
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| 35 | global new_interpreter
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| 36 | usage = ('usage: %s -i /interpreter file-or-directory ...\n' %
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| 37 | sys.argv[0])
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| 38 | try:
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| 39 | opts, args = getopt.getopt(sys.argv[1:], 'i:')
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| 40 | except getopt.error, msg:
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| 41 | err(msg + '\n')
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| 42 | err(usage)
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| 43 | sys.exit(2)
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| 44 | for o, a in opts:
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| 45 | if o == '-i':
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| 46 | new_interpreter = a
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| 47 | if not new_interpreter or new_interpreter[0] != '/' or not args:
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| 48 | err('-i option or file-or-directory missing\n')
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| 49 | err(usage)
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| 50 | sys.exit(2)
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| 51 | bad = 0
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| 52 | for arg in args:
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| 53 | if os.path.isdir(arg):
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| 54 | if recursedown(arg): bad = 1
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| 55 | elif os.path.islink(arg):
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| 56 | err(arg + ': will not process symbolic links\n')
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| 57 | bad = 1
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| 58 | else:
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| 59 | if fix(arg): bad = 1
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| 60 | sys.exit(bad)
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| 61 |
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| 62 | ispythonprog = re.compile('^[a-zA-Z0-9_]+\.py$')
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| 63 | def ispython(name):
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| 64 | return ispythonprog.match(name) >= 0
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| 65 |
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| 66 | def recursedown(dirname):
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| 67 | dbg('recursedown(%r)\n' % (dirname,))
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| 68 | bad = 0
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| 69 | try:
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| 70 | names = os.listdir(dirname)
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| 71 | except os.error, msg:
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| 72 | err('%s: cannot list directory: %r\n' % (dirname, msg))
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| 73 | return 1
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| 74 | names.sort()
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| 75 | subdirs = []
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| 76 | for name in names:
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| 77 | if name in (os.curdir, os.pardir): continue
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| 78 | fullname = os.path.join(dirname, name)
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| 79 | if os.path.islink(fullname): pass
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| 80 | elif os.path.isdir(fullname):
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| 81 | subdirs.append(fullname)
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| 82 | elif ispython(name):
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| 83 | if fix(fullname): bad = 1
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| 84 | for fullname in subdirs:
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| 85 | if recursedown(fullname): bad = 1
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| 86 | return bad
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| 87 |
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| 88 | def fix(filename):
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| 89 | ## dbg('fix(%r)\n' % (filename,))
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| 90 | try:
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| 91 | f = open(filename, 'r')
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| 92 | except IOError, msg:
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| 93 | err('%s: cannot open: %r\n' % (filename, msg))
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| 94 | return 1
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| 95 | line = f.readline()
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| 96 | fixed = fixline(line)
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| 97 | if line == fixed:
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| 98 | rep(filename+': no change\n')
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| 99 | f.close()
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| 100 | return
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| 101 | head, tail = os.path.split(filename)
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| 102 | tempname = os.path.join(head, '@' + tail)
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| 103 | try:
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| 104 | g = open(tempname, 'w')
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| 105 | except IOError, msg:
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| 106 | f.close()
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| 107 | err('%s: cannot create: %r\n' % (tempname, msg))
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| 108 | return 1
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| 109 | rep(filename + ': updating\n')
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| 110 | g.write(fixed)
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| 111 | BUFSIZE = 8*1024
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| 112 | while 1:
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| 113 | buf = f.read(BUFSIZE)
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| 114 | if not buf: break
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| 115 | g.write(buf)
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| 116 | g.close()
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| 117 | f.close()
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| 118 |
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| 119 | # Finishing touch -- move files
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| 120 |
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| 121 | # First copy the file's mode to the temp file
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| 122 | try:
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| 123 | statbuf = os.stat(filename)
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| 124 | os.chmod(tempname, statbuf[ST_MODE] & 07777)
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| 125 | except os.error, msg:
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| 126 | err('%s: warning: chmod failed (%r)\n' % (tempname, msg))
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| 127 | # Then make a backup of the original file as filename~
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| 128 | try:
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| 129 | os.rename(filename, filename + '~')
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| 130 | except os.error, msg:
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| 131 | err('%s: warning: backup failed (%r)\n' % (filename, msg))
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| 132 | # Now move the temp file to the original file
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| 133 | try:
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| 134 | os.rename(tempname, filename)
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| 135 | except os.error, msg:
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| 136 | err('%s: rename failed (%r)\n' % (filename, msg))
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| 137 | return 1
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| 138 | # Return success
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| 139 | return 0
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| 140 |
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| 141 | def fixline(line):
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| 142 | if not line.startswith('#!'):
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| 143 | return line
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| 144 | if "python" not in line:
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| 145 | return line
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| 146 | return '#! %s\n' % new_interpreter
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| 147 |
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| 148 | if __name__ == '__main__':
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| 149 | main()
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