151 lines
4.3 KiB
Python
Executable File
151 lines
4.3 KiB
Python
Executable File
#!/usr/bin/env python3
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# Change the #! line occurring in Python scripts. The new interpreter
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# pathname must be given with a -i option.
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#
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# Command line arguments are files or directories to be processed.
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# Directories are searched recursively for files whose name looks
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# like a python module.
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# Symbolic links are always ignored (except as explicit directory
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# arguments). Of course, the original file is kept as a back-up
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# (with a "~" attached to its name).
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#
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# Undoubtedly you can do this using find and sed or perl, but this is
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# a nice example of Python code that recurses down a directory tree
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# and uses regular expressions. Also note several subtleties like
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# preserving the file's mode and avoiding to even write a temp file
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# when no changes are needed for a file.
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#
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# NB: by changing only the function fixfile() you can turn this
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# into a program for a different change to Python programs...
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import sys
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import re
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import os
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from stat import *
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import getopt
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err = sys.stderr.write
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dbg = err
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rep = sys.stdout.write
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new_interpreter = None
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def main():
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global new_interpreter
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usage = ('usage: %s -i /interpreter file-or-directory ...\n' %
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sys.argv[0])
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try:
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opts, args = getopt.getopt(sys.argv[1:], 'i:')
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except getopt.error as msg:
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err(msg + '\n')
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err(usage)
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sys.exit(2)
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for o, a in opts:
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if o == '-i':
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new_interpreter = a.encode()
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if not new_interpreter or not new_interpreter.startswith(b'/') or \
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not args:
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err('-i option or file-or-directory missing\n')
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err(usage)
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sys.exit(2)
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bad = 0
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for arg in args:
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if os.path.isdir(arg):
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if recursedown(arg): bad = 1
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elif os.path.islink(arg):
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err(arg + ': will not process symbolic links\n')
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bad = 1
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else:
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if fix(arg): bad = 1
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sys.exit(bad)
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ispythonprog = re.compile('^[a-zA-Z0-9_]+\.py$')
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def ispython(name):
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return bool(ispythonprog.match(name))
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def recursedown(dirname):
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dbg('recursedown(%r)\n' % (dirname,))
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bad = 0
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try:
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names = os.listdir(dirname)
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except os.error as msg:
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err('%s: cannot list directory: %r\n' % (dirname, msg))
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return 1
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names.sort()
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subdirs = []
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for name in names:
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if name in (os.curdir, os.pardir): continue
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fullname = os.path.join(dirname, name)
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if os.path.islink(fullname): pass
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elif os.path.isdir(fullname):
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subdirs.append(fullname)
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elif ispython(name):
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if fix(fullname): bad = 1
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for fullname in subdirs:
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if recursedown(fullname): bad = 1
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return bad
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def fix(filename):
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## dbg('fix(%r)\n' % (filename,))
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try:
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f = open(filename, 'rb')
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except IOError as msg:
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err('%s: cannot open: %r\n' % (filename, msg))
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return 1
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line = f.readline()
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fixed = fixline(line)
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if line == fixed:
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rep(filename+': no change\n')
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f.close()
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return
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head, tail = os.path.split(filename)
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tempname = os.path.join(head, '@' + tail)
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try:
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g = open(tempname, 'wb')
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except IOError as msg:
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f.close()
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err('%s: cannot create: %r\n' % (tempname, msg))
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return 1
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rep(filename + ': updating\n')
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g.write(fixed)
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BUFSIZE = 8*1024
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while 1:
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buf = f.read(BUFSIZE)
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if not buf: break
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g.write(buf)
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g.close()
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f.close()
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# Finishing touch -- move files
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# First copy the file's mode to the temp file
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try:
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statbuf = os.stat(filename)
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os.chmod(tempname, statbuf[ST_MODE] & 0o7777)
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except os.error as msg:
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err('%s: warning: chmod failed (%r)\n' % (tempname, msg))
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# Then make a backup of the original file as filename~
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try:
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os.rename(filename, filename + '~')
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except os.error as msg:
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err('%s: warning: backup failed (%r)\n' % (filename, msg))
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# Now move the temp file to the original file
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try:
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os.rename(tempname, filename)
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except os.error as msg:
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err('%s: rename failed (%r)\n' % (filename, msg))
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return 1
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# Return succes
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return 0
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def fixline(line):
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if not line.startswith(b'#!'):
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return line
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if b"python" not in line:
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return line
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return b'#! ' + new_interpreter + b'\n'
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if __name__ == '__main__':
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main()
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