replace ALL instances of a character with another one in all files hierarchically in directory tree
<p>so the command line will look like :</p>

<p>./replace.py   </p>

<p>current directory may be /home/user
before = "\"
after = '/"</p>

<p>which means replacing backslash with / forward slash in ALL files. Now the ONLY place where this replacement takes place is when the LINE contains text "path"</p>

<p>here is what i have , which actually does replace text, but not / , or \</p>

<pre><code>#!/usr/bin/python
import os
import re
import sys

#print f.readline().replace('\\','/')
#replace_extensions = []
replace_extensions = [".tst"]

def try_to_replace(fname):
    if replace_extensions:
        return fname.lower().endswith(replace_extensions)
    return True


def file_replace(fname, pat, s_after):
    with open(fname) as f:
        if not any(re.search(pat, line) for line in f):
            return

    with open(fname) as f:
        out_fname = fname + ".tmp"
        out = open(out_fname, "w")
        for line in f:
            out.write(re.sub(pat, s_after, line))
        out.close()
        os.rename(out_fname, fname)


def mass_replace(dir_name, s_before, s_after):
    pat = re.compile(s_before)
    for dirpath, dirnames, filenames in os.walk(dir_name):
        for fname in filenames:
            if try_to_replace(fname):
                fullname = os.path.join(dirpath, fname)
                file_replace(fullname, pat, s_after)

if len(sys.argv) != 4:
    u = "Usage: mass_replace &lt;dir_name&gt; &lt;string_before&gt; &lt;string_after&gt;\n"
    sys.stderr.write(u)
    sys.exit(1)

mass_replace(sys.argv[1], sys.argv[2], sys.argv[3])
</code></pre>

<p>and i get error:</p>

<pre><code>./mass_replace.py test1 '\\' '/'
Traceback (most recent call last):
  File "./mass_replace.py", line 43, in &lt;module&gt;
    mass_replace(sys.argv[1], sys.argv[2], sys.argv[3])
  File "./mass_replace.py", line 34, in mass_replace
    if try_to_replace(fname):
  File "./mass_replace.py", line 12, in try_to_replace
    return fname.lower().endswith(replace_extensions)
TypeError: expected a character buffer object
</code></pre>
