How to remove trailing whitespace in code using another script

Question

Something like   import fileinput  for lines in fileinput FileInput  test txt   inplace 1       lines   lines strip       if lines        continue     print lines   But nothing is being printed on stdout   Assuming some string named foo   foo lstrip     to remove leading white space foo rstrip     to remove trailing whitespace foo strip      to remove both lead and trailing whitespace

User · Answer

Save as fix whitespace py      usr bin env python     Fix trailing whitespace and line endings  to Unix  in a file  Usage  python fix whitespace py foo py      import os import sys   def main            Parse arguments  then fix whitespace in the given file         if len sys argv     2          fname   sys argv 1          if not os path exists fname               print  Python file not found   s    sys argv 1               sys exit 1      else          print  Invalid arguments  Usage  python fix whitespace py foo py           sys exit 1      fix whitespace fname    def fix whitespace fname           Fix whitespace in a file         with open fname   rb   as fo          original contents   fo read          rU  Universal line endings to Unix     with open fname   rU   as fo          contents   fo read       lines   contents split   n       fixed   0     for k  line in enumerate lines           new line   line rstrip           if len line     len new line               lines k    new line             fixed    1     with open fname   wb   as fo          fo write   n  join lines       if fixed or contents    original contents          print                 s    os path basename fname       if fixed          slines    lines  if fixed  gt  1 else  line          print  Fixed trailing whitespace on  d  s                     fixed  slines       if contents    original contents          print  Fixed line endings to Unix    n      if   name         main         main

User · Answer

It seems  fileinput FileInput is a generator  As such  you can only iterate over it once  then all items have been consumed and calling it s next method raises StopIteration  If you want to iterate over the lines more than once  you can put them in a list   list fileinput FileInput  test txt      Then call rstrip on them

User · Answer

This is the sort of thing that sed is really good at    sed  s    t        Be aware the you will probably need to literally type a TAB character instead of  t for this to work

User · Answer

It s a bit surprising seeing multiple answers suggesting to use python for this task  as there s no need to write a multi-line program for this  Standard Unix tools like sed  awk or perl can achieve this easily straight from the command-line  e g anywhere you have perl  Windows  Mac  Linux  the following should achieve what the OP asked  perl -i -pe  s    t        files     Explanation of the arguments to perl  -i     run the edit  quot in place quot   modify the original file  -p     implies a loop with a final print over every input line -e     next arg is the perl expression to apply  to every line   s    t      is a substitution regex s FROM TO   replace every trailing  end of line  non-empty space  spaces or tabs  with nothing  Advantages   One liner  no programming needed Works on multiple  any number  of files Works correctly on standard-input  no file arguments given    Edit  Newer versions of perl support  h  any horizontal-space character   so the solution becomes even shorter      perl -i -pe  s  h       files     More generally  if you want to modify any number of files directly from the command line  replacing every appearance of FOO with BAR  you may always use this generic template  perl -i -pe  s FOO BAR   files

User · Answer

fileinput seems to be for multiple input streams  This is what I would do   with open  test txt   as file      for line in file          line   line rstrip           if line              print line

User · Answer

You don t see any output from the print statements because FileInput redirects stdout to the input file when the keyword argument inplace 1 is given  This causes the input file to effectively be rewritten and if you look at it afterwards the lines in it will indeed have no trailing or leading whitespace in them  except for the newline at the end of each which the print statement adds back    If you only want to remove trailing whitespace  you should use rstrip   instead of strip    Also note that the if lines        continue is causing blank lines to be completely removed  regardless of whether strip or rstrip gets used    Unless your intent is to rewrite the input file  you should probably just use for line in open filename    Otherwise you can see what s being written to the file by simultaneously echoing the output to sys stderr using something like the following   import fileinput import sys  for line in  line rstrip   for line in                 fileinput FileInput  test txt   inplace 1        if line          print line         print  gt  gt sys stderr  line

User · Answer

If you re looking to tidy up for PEP8  this will trim trailing whitespace for your whole project   import os  PATH     path to your project   for path  dirs  files in os walk PATH       for f in files          file name  file extension   os path splitext f          if file extension      py               path name   os path join path  f              with open path name   r   as fh                  new    line rstrip   for line in fh              with open path name   w   as fh                   fh write   s n    line  for line in new

[python] How to remove trailing whitespace in code, using another script?

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