Edit File: pathfix.py
#! /usr/bin/python2.7 # Change the #! line occurring in Python scripts. The new interpreter # pathname must be given with a -i option. # # Command line arguments are files or directories to be processed. # Directories are searched recursively for files whose name looks # like a python module. # Symbolic links are always ignored (except as explicit directory # arguments). Of course, the original file is kept as a back-up # (with a "~" attached to its name). # # Undoubtedly you can do this using find and sed or perl, but this is # a nice example of Python code that recurses down a directory tree # and uses regular expressions. Also note several subtleties like # preserving the file's mode and avoiding to even write a temp file # when no changes are needed for a file. # # NB: by changing only the function fixfile() you can turn this # into a program for a different change to Python programs... import sys import re import os from stat import * import getopt err = sys.stderr.write dbg = err rep = sys.stdout.write new_interpreter = None def main(): global new_interpreter usage = ('usage: %s -i /interpreter file-or-directory ...\n' % sys.argv[0]) try: opts, args = getopt.getopt(sys.argv[1:], 'i:') except getopt.error, msg: err(msg + '\n') err(usage) sys.exit(2) for o, a in opts: if o == '-i': new_interpreter = a if not new_interpreter or new_interpreter[0] != '/' or not args: err('-i option or file-or-directory missing\n') err(usage) sys.exit(2) bad = 0 for arg in args: if os.path.isdir(arg): if recursedown(arg): bad = 1 elif os.path.islink(arg): err(arg + ': will not process symbolic links\n') bad = 1 else: if fix(arg): bad = 1 sys.exit(bad) ispythonprog = re.compile('^[a-zA-Z0-9_]+\.py$') def ispython(name): return ispythonprog.match(name) >= 0 def recursedown(dirname): dbg('recursedown(%r)\n' % (dirname,)) bad = 0 try: names = os.listdir(dirname) except os.error, msg: err('%s: cannot list directory: %r\n' % (dirname, msg)) return 1 names.sort() subdirs = [] for name in names: if name in (os.curdir, os.pardir): continue fullname = os.path.join(dirname, name) if os.path.islink(fullname): pass elif os.path.isdir(fullname): subdirs.append(fullname) elif ispython(name): if fix(fullname): bad = 1 for fullname in subdirs: if recursedown(fullname): bad = 1 return bad def fix(filename): ## dbg('fix(%r)\n' % (filename,)) try: f = open(filename, 'r') except IOError, msg: err('%s: cannot open: %r\n' % (filename, msg)) return 1 line = f.readline() fixed = fixline(line) if line == fixed: rep(filename+': no change\n') f.close() return head, tail = os.path.split(filename) tempname = os.path.join(head, '@' + tail) try: g = open(tempname, 'w') except IOError, msg: f.close() err('%s: cannot create: %r\n' % (tempname, msg)) return 1 rep(filename + ': updating\n') g.write(fixed) BUFSIZE = 8*1024 while 1: buf = f.read(BUFSIZE) if not buf: break g.write(buf) g.close() f.close() # Finishing touch -- move files # First copy the file's mode to the temp file try: statbuf = os.stat(filename) os.chmod(tempname, statbuf[ST_MODE] & 07777) except os.error, msg: err('%s: warning: chmod failed (%r)\n' % (tempname, msg)) # Then make a backup of the original file as filename~ try: os.rename(filename, filename + '~') except os.error, msg: err('%s: warning: backup failed (%r)\n' % (filename, msg)) # Now move the temp file to the original file try: os.rename(tempname, filename) except os.error, msg: err('%s: rename failed (%r)\n' % (filename, msg)) return 1 # Return success return 0 def fixline(line): if not line.startswith('#!'): return line if "python" not in line: return line return '#! %s\n' % new_interpreter if __name__ == '__main__': main()
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