Python 之 filecmp
2017年7月12日
参考书籍:《Python自动化运维 ——技术与最佳实践》 作者:李天斯
1.什么是filecmp
filecmp作为python的标准库，无需安装，作用是对文件，目录，遍历子目录的差异对比功能，它是一个轻量级的工具，在对linux服务器备份文件检验时非常有用。
2.filecmp的简单使用
2.1 cmp的简单使用
用法:filecmp.cmp(file1,file2),如果file1和file2相同的话，则会返回true，否则返回false,这就称为比较单文件的差异。
2.1.1 copy一个文件备份两次
# cp /etc/vnc.conf ./ # cp /etc/vnc.conf ./vnc.conf.bak
2.1.2 编写python代码
# cat lcmp.py
#!/usr/bin/env python
import sys
import filecmp
import os
try:
file1 = sys.argv[1]
file2 = sys.argv[2]
except:
print ("Please follow the parameters")
sys.exit()
if os.path.isfile(file1) and os.path.isfile(file2) :
if filecmp.cmp(file1,file2):
print ("Match success")
else :
print ("Match failed")
else:
print ("Please check files")
sys.exit()
2.1.2 执行脚本输出
# python lcmp.py vnc.conf vnc.conf.bak Match success
由上诉结果可以看出,文件是对比OK了的，现在修改vnc.conf.bak的内容，再执行脚本
2.1.3再次执行
# sed -i s/vnc/liwang.org/ vnc.conf.bak # python lcmp.py vnc.conf vnc.conf.bak Match failed
比对文件不成功，则输出了Match failed ,则证明脚本是ok的
2.2 cmpfiles的简单使用
用法:filecmp.cmpfiles(dir1,dir2,common[files...]),作用是对比dir1 和 dir2 目录的差异，该方法会返回三个list,分别是匹配，不匹配，错误。
2.2.1 复制文件
# mkdir -p dir1 dir2 # cp lcmp.py vnc.conf vnc.conf.bak dir1/ # cp lcmp.py vnc.conf dir2/
2.2.2 编写python代码
# cat lcmpfiles.py
#!/usr/bin/env python
import os
import filecmp
import sys
dir1 = input("Please enter a folder to match:")
dir2 = input("Please enter a folder to match:")
files = []
while True:
local_files = input("Please enter the file to compare:[n/N Exit the input]")
if local_files == 'N' or local_files == 'n':
break
elif local_files == '':
continue
else :
files.append(local_files)
try:
os.path.exists(dir1)
os.path.exists(dir2)
except:
print ("Pleae check the folder.")
sys.exit()
#print (filecmp.cmpfiles(dir1,dir2,files)[0])
print ("It's file match:",filecmp.cmpfiles(dir1,dir2,files)[0])
print ("The file does not match:",filecmp.cmpfiles(dir1,dir2,files)[1])
print ("File does not exists:",filecmp.cmpfiles(dir1,dir2,files)[2])
2.2.3 用python3执行脚本(因为使用了input)
# python3 lcmpfiles.py Please enter a folder to match:dir1 Please enter a folder to match:dir2 Please enter the file to compare:[n/N Exit the input]lcmp.py Please enter the file to compare:[n/N Exit the input]vnc.conf Please enter the file to compare:[n/N Exit the input]vnc.conf.bak Please enter the file to compare:[n/N Exit the input]n It's file match: ['lcmp.py', 'vnc.conf'] The file does not match: [] File does not exists: ['vnc.conf.bak']
可以看出，lcmp.py 和 vnc.conf 在dir1 和dr2都有，且文件内容相同，而vnc.conf.bak在dir1有，dir没有，故输出，文件匹配:lcmp.py和vnc.conf ，文件不存在:vnc.conf.bak,文件不相同:无
2.2 dircmp的简单使用
语法:dircmp(a,b,[,ignore[,hide]]) 其中a,b是文件名，ignore是可以忽略的列表，hide代表隐藏列表,dircmp可以获得目录比较详细的信息，同时还支持递归。
dircmp提供了三个输出方法:
report() 比较当前指定目录中的内容
report_full_closure() 递归比较所有指定文件的内容
2.2.1 模拟环境
# ls dir1/ dir2/ dir1/: hosts ld.so.conf sysconfig dir2/: hosts ld.so.conf sysconfig
其中,sysconfig 是一个目录 hosts 和 ld.so.conf都是文件,且hosts内容不一致 sysconfig中的文件也不一样
2.2.2 编写python代码
2.2.2.1 dircmp.report()
# cat simple_filecmp.py #!/usr/bin/env python import filecmp dir1 = "/root/python/d_2_filecmp/cmp/dir2" dir2 = "/root/python/d_2_filecmp/cmp/dir1" dirobj = filecmp.dircmp(dir1,dir2) print (dirobj.report())
2.2.2.2 执行脚本
# python simple_filecmp.py diff /root/python/d_2_filecmp/cmp/dir2 /root/python/d_2_filecmp/cmp/dir1 Identical files : ['ld.so.conf'] Differing files : ['hosts'] Common subdirectories : ['sysconfig'] None [root@localhost cmp]# cat simple_filecmp.py
由上面的结果，我们可以看出，report只能比对脚本的首层目录,而无法对子文件夹下的目录进行匹配
2.2.2.3 report_full_closure()
# cat simple_filecmp_2.py #!/usr/bin/env python import filecmp dir1 = "/root/python/d_2_filecmp/cmp/dir1/" dir2 = "/root/python/d_2_filecmp/cmp/dir2/" dirobj = filecmp.dircmp(dir1,dir2) print (dirobj.report_full_closure())
2.2.2.4 执行脚本
diff /root/python/d_2_filecmp/cmp/dir1/ /root/python/d_2_filecmp/cmp/dir2/ Identical files : ['ld.so.conf'] Differing files : ['hosts'] Common subdirectories : ['sysconfig'] diff/root/python/d_2_filecmp/cmp/dir1/sysconfig /root/python/d_2_filecmp/cmp/dir2/sysconfig ......
由此可见差别report()和report_full_closure()的差别在于
3.filecmp案例
3.1 需求
需求：1.备份etc 文件夹下所有的内容,并且保持实时备份,如果有新的文件，则copy至备份文件中，如果有新的，则update之
3.2 流程图
3.2.1 初步流程图:
3.2.2 对比文件差异流程图
3.3 代码编写:
3.3.1 补充知识:
dircmp.left_only
只在左边出现的文件
# cat simple_filecmp_3.py #!/usr/bin/env python import filecmp dir1 = "/root/python/d_2_filecmp/cmp/dir1/" dir2 = "/root/python/d_2_filecmp/cmp/dir2/" dirobj = filecmp.dircmp(dir1,dir2) print (dirobj.diff_files)
执行结果
# ls dir1 dir2/ dir1: hosts ld.so.conf sysconfig teacher dir2/: hosts ld.so.conf sysconfig [root@localhost cmp]# python simple_filecmp_3.py ['teacher']
由上诉可见,当teacher只出现在dir1时,则会被抓取出来,所谓的left和right是相对于filecmp.dircmp而言的
dircmp.diff_files
返回不能匹配额文件
# cat simple_filecmp_3.py #!/usr/bin/env python import filecmp dir1 = "/root/python/d_2_filecmp/cmp/dir1/" dir2 = "/root/python/d_2_filecmp/cmp/dir2/" dirobj = filecmp.dircmp(dir1,dir2) print (dirobj.diff_files) #print (dirobj.left_only)
执行结果
[root@localhost cmp]# ls dir1 dir2 dir1: hosts ld.so.conf sysconfig teacher dir2: hosts ld.so.conf sysconfig [root@localhost cmp]# python simple_filecmp_3.py ['hosts'] [root@localhost cmp]#
之前我们修改过hosts的文件，文件内容已经不一致，现在已经被抓取出来了
3.3.2 编写自动备份脚本
# cat d_7_12_filecmp.py
#!/usr/bin/env python
import filecmp
import os
import sys
import shutil
source_files = "/root/python/d_2_filecmp/dir1"
target_files = "/root/python/d_2_filecmp/dir2"
def check_common_dirs(source_files,target_files):
dirsobj = filecmp.dircmp(source_files , target_files)
common_dirs_list = dirsobj.common_dirs
for common_line in common_dirs_list :
files_contrast('/'+source_files+'/'+common_line,'/'+target_files+'/'+common_line)
def files_contrast(dir1,dir2) :
dirobj = filecmp.dircmp(dir1,dir2)
no_exists_files = dirobj.left_only
no_diff_files = dirobj.diff_files
for exists_files in no_exists_files :
if os.path.isfile(exists_files) :
shutil.copyfile ('/'+dir1+'/'+exists_files , '/'+dir2+'/'+exists_files)
else :
print ("%s is dirctory" %(exists_files))
os.makedirs('/'+dir2+'/'+exists_files)
print ("%s is mkdirs" %('/'+target_files+'/'+exists_files))
try :
print ("values : %s %s" %('/'+dir1+'/'+exists_files , '/'+dir2+'/'+exists_files))
files_contrast('/'+dir1+'/'+exists_files , '/'+dir2+'/'+exists_files)
except :
return
for diff_files in no_diff_files :
if os.path.isfile(diff_files) :
os.remove('/'+dir2+'/'+diff_files)
shutil.copyfile ('/'+dir1+'/'+diff_files , '/'+dir2+'/'+diff_files)
if os.path.exists(source_files) :
if os.path.exists(target_files) == "False" :
os.makedirs(target_files)
files_contrast(source_files,target_files)
check_common_dirs(source_files,target_files)
else :
print ("Soure files no exists")
sys.exit()
3.4 执行脚本输出
3.4.1 查看文件
可知 dir2下没有任何文件
# tree dir1/ dir2/ dir1/ ├── │ └── ├── │ └── │ └── d ├── lcmp.py ├── vnc.conf └── vnc.conf.bak dir2/ directories, files
3.4.2 执行脚本
root@localhost d_2_filecmp]# python d_7_12_filecmp.py is dirctory //root/python/d_2_filecmp/dir2/4556 is mkdirs values : //root/python/d_2_filecmp/dir1/4556 //root/python/d_2_filecmp/dir2/4556 is dirctory //root/python/d_2_filecmp/dir2/789 is mkdirs values : ///root/python/d_2_filecmp/dir1/4556/789 ///root/python/d_2_filecmp/dir2/4556/789 d is dirctory //root/python/d_2_filecmp/dir2/d is mkdirs values : ////root/python/d_2_filecmp/dir1/4556/789/d ////root/python/d_2_filecmp/dir2/4556/789/d is dirctory //root/python/d_2_filecmp/dir2/123 is mkdirs values : //root/python/d_2_filecmp/dir1/123 //root/python/d_2_filecmp/dir2/123 is dirctory //root/python/d_2_filecmp/dir2/123456 is mkdirs values : ///root/python/d_2_filecmp/dir1/123/123456 ///root/python/d_2_filecmp/dir2/123/123456
可以看出,备份的信息,前面的多个/可以不必理会，linux只识别一个/
3.4.3 查看备份效果
# tree dir1/ dir2/ dir1/ ├── │ └── ├── │ └── │ └── d ├── lcmp.py ├── vnc.conf └── vnc.conf.bak dir2/ ├── │ └── ├── │ └── │ └── d ├── lcmp.py ├── vnc.conf └── vnc.conf.bak directories, files
由上，可知,备份完全成功，针对于定时执行python脚本,可以将脚本写入crontab中，开启定时任务即可。