我有下面的代码做除了我想要的一切:-)。目标很简单,我试图在目录(和子目录)中存在的每个文件的顶部添加appendtext变量中的文本,脚本运行正常但是文字没有附加......我哪里错了?
import os
import sys
import fnmatch
temp_fname = "temp_file"
appendtext="""Test string
"""
if len(sys.argv) < 2:
sys.exit('Usage: test.py <build directory>')
for path,dirs,files in os.walk(sys.argv[1]):
for fname in files:
for pat in ['*.*']:
if fnmatch.fnmatch(fname,pat):
fullname = os.path.join(path,fname)
with open(fullname, "r") as in_file:
with open(temp_fname, "w") as out_file:
out_file.write(appendtext)
for line in in_file:
out_file.write(line)
os.rename(temp_fname, fullname)
答案 0 :(得分:2)
如果您希望文本顶部的文本,您应该这样做:
temp_fname = "temp_file"
# the next line doesn't work in Python 2.5, 2.6, or 3.0
with open(fullname, "r") as in_file, open(temp_fname, "w") as out_file:
out_file.write(appendtext)
for line in in_file:
out_file.write(line)
os.rename(temp_fname, fullname)
以上是Python 2.6重写的内容:
temp_fname = "temp_file"
with open(temp_fname, "w") as out_file:
with open(fullname, "r") as in_file:
out_file.write(appendtext)
for line in in_file:
out_file.write(line)
os.rename(temp_fname, fullname)
我们可以比这更好一些。这始终使用相同的临时文件名("temp_file"
),并且该文件将始终在单个目录中创建(运行此目录时为默认目录)。我们真正想要的是一个临时文件,它具有唯一的名称,创建在与我们将要编辑的文件完全相同的目录中。 Python为我们提供了一个名为tempfile
的方便模块,用于创建临时文件。
默认情况下,您只是获得一个打开的文件句柄而您不知道文件名。但我们需要知道文件名,以便在完成临时复制后,我们可以将其重命名为原始文件名。 tempfile
为此类案件提供了NamedTemporaryFile
。
这是一个完整的程序:
import fnmatch
import os
import sys
import tempfile
headertext = "# header text\n\n"
def want_this_file(fname):
for pat in ['*']:
if fnmatch.fnmatch(fname, pat):
return True
return False
def prepend_file(fullname, path):
# with statement means temp file is written and closed at end of with
with tempfile.NamedTemporaryFile(dir=path, delete=False) as out_file:
with open(fullname, "r") as in_file:
out_file.write(headertext)
for line in in_file:
out_file.write(line)
# before temp file is closed, get its name
temp_fname = out_file.name
# rename temp file to fullname, clobbering original
os.rename(temp_fname, fullname)
start_directory = sys.argv[1]
for dirpath, dirnames, filenames in os.walk(start_directory):
for fname in filenames:
if want_this_file(fname):
fullname = os.path.join(dirpath, fname)
prepend_file(fullname, dirpath)
此答案使用“编写临时文件,然后将临时文件重命名为原始名称”模式。这是你应该这样做的方式。它允许代码编写新版本,并且只有在新版本完全成功编写时,然后执行单个操作才能将新文件重命名为旧文件名。因此,如果在尝试编写新版本时出现任何问题,原始文件保持不变。这是解决问题的安全方法。
我们希望在与原始文件相同的目录中创建临时文件,这样os.rename()
操作将非常便宜。在Linux系统上,系统临时目录(/tmp
)可能位于其自己的分区上,如果您只是让tempfile
在其中创建临时文件,则重命名操作可能涉及再次复制数据!如果临时文件位于同一目录中,则重命名操作始终非常快速且安全。
编辑:这是代码的改进版本。这会捕获错误,并在重新引发发出错误的异常之前清除临时文件。另外,正如J.F.Sebastian指出的那样,文件应该以二进制模式打开;这样做。
import fnmatch
import os
import shutil
import sys
import tempfile
file_patterns_to_match = ['*']
headertext = "# header text\n\n"
# make any newlines in headertext match the system line ending
headertext = headertext.replace('\n', os.linesep)
def want_this_file(fname):
for pat in file_patterns_to_match:
if fnmatch.fnmatch(fname, pat):
return True
return False
def prepend_file(fullname, path):
# with statement means temp file is written and closed at end of with
with tempfile.NamedTemporaryFile(dir=path, delete=False) as out_file:
# get the name immediately
temp_fname = out_file.name
try:
# use binary mode to avoid newline translations
with open(fullname, "rb") as in_file:
out_file.write(headertext)
shutil.copyfileobj(in_file, out_file)
except Exception:
# on any error, clean up temp file and re-raise exception
try:
os.remove(temp_fname)
except Exception:
print("unable to clean up temp file: " + temp_fname)
pass
raise
# rename temp file to fullname, clobbering original
os.rename(temp_fname, fullname)
start_directory = sys.argv[1]
for dirpath, dirnames, filenames in os.walk(start_directory):
for fname in filenames:
if want_this_file(fname):
fullname = os.path.join(dirpath, fname)
prepend_file(fullname, dirpath)
答案 1 :(得分:0)
我知道你的问题是关于你的python脚本。但是你可以使用perl在bash中实现这一点。
sgeorge-mn:stack sgeorge$ cat file_0*
Hi - 1
Hi - 2
Hi - 3
Hi - 4
Hi - 5
sgeorge-mn:stack sgeorge$ find . -type f
./file_01.txt
./file_02.txt
./file_03.txt
./file_04.txt
./file_05.txt
sgeorge-mn:stack sgeorge$ find . -type f -exec perl -pi -e 'print "Please donot add any comments \nThis is a header file.\nJust a test.\n" if $. == 1' {} \;
sgeorge-mn:stack sgeorge$ cat file_0*
Please donot add any comments
This is a header file.
Just a test.
Hi - 1
Please donot add any comments
This is a header file.
Just a test.
Hi - 2
Please donot add any comments
This is a header file.
Just a test.
Hi - 3
Please donot add any comments
This is a header file.
Just a test.
Hi - 4
Please donot add any comments
This is a header file.
Just a test.
Hi - 5