使用fileinput.input将行插入文件

Question

I want to insert a line into the middle of a text file that I have.

I have tried:

for line in fileinput.input('file.txt', inplace=1):
    if line.startswith('example'):
        print 'input line'

which worked. But I wanted this to loop over many files, so I changed it to:

for line in fileinput.input('{0}' .format(file), inplace=1):
    if line.startswith('example'):
        print 'input line'

and I get the error message:

Traceback (most recent call last):
  File "addline.py", line 8, in <module>
    for line in fileinput.input('{0}' .format(file), inplace=1):
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/fileinput.py", line 253, in next
    line = self.readline()
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/fileinput.py", line 322, in readline
    os.rename(self._filename, self._backupfilename)
OSError: [Errno 2] No such file or directory

I would like to know why this doesn't work and any suggestions to fix would be appreciated.

Answer 1

The problem seems to be in this line:

for line in fileinput.input('{0}' .format(file), inplace=1):

change to this:

# f is the filename
for line in fileinput.input('{0}'.format(f), inplace=1):

First problem, change file to other name, file is a reserved name in python.

And, make sure you're passing a list of filenames if you were trying to pass multiple files.

Try changing to this:

...
files = ['file1', 'file2', ...] # put your files in a list first
# and pass the list of files to .input
for line in fileinput.input(files, inplace=1):
...