filecmp --- 檔案與目錄比較

原始碼：Lib/filecmp.py

Thefilecmp module defines functions to compare files and directories,with various optional time/correctness trade-offs. For comparing files,see also thedifflib module.

Thefilecmp module defines the following functions:

filecmp.cmp(f1,f2,shallow=True)

Compare the files namedf1 andf2, returningTrue if they seem equal,False otherwise.

Ifshallow is true and theos.stat() signatures (file type, size, andmodification time) of both files are identical, the files are taken to beequal.

Otherwise, the files are treated as different if their sizes or contents differ.

Note that no external programs are called from this function, giving itportability and efficiency.

This function uses a cache for past comparisons and the results,with cache entries invalidated if theos.stat() information for thefile changes. The entire cache may be cleared usingclear_cache().

filecmp.cmpfiles(dir1,dir2,common,shallow=True)

Compare the files in the two directoriesdir1 anddir2 whose names aregiven bycommon.

Returns three lists of file names:match,mismatch,errors.match contains the list of files that match,mismatch containsthe names of those that don't, anderrors lists the names of files whichcould not be compared. Files are listed inerrors if they don't exist inone of the directories, the user lacks permission to read them or if thecomparison could not be done for some other reason.

Theshallow parameter has the same meaning and default value as forfilecmp.cmp().

For example,cmpfiles('a','b',['c','d/e']) will comparea/c withb/c anda/d/e withb/d/e.'c' and'd/e' will each be inone of the three returned lists.

filecmp.clear_cache()

Clear the filecmp cache. This may be useful if a file is compared so quicklyafter it is modified that it is within the mtime resolution ofthe underlying filesystem.

在 3.4 版被加入.

Thedircmp class

classfilecmp.dircmp(a,b,ignore=None,hide=None,*,shallow=True)

Construct a new directory comparison object, to compare the directoriesaandb.ignore is a list of names to ignore, and defaults tofilecmp.DEFAULT_IGNORES.hide is a list of names to hide, anddefaults to[os.curdir,os.pardir].

Thedircmp class compares files by doingshallow comparisonsas described forfilecmp.cmp() by default using theshallowparameter.

在 3.13 版的變更:Added theshallow parameter.

Thedircmp class provides the following methods:

report()

Print (tosys.stdout) a comparison betweena andb.

report_partial_closure()

Print a comparison betweena andb and common immediatesubdirectories.

report_full_closure()

Print a comparison betweena andb and common subdirectories(recursively).

Thedircmp class offers a number of interesting attributes that may beused to get various bits of information about the directory trees beingcompared.

Note that via__getattr__() hooks, all attributes are computed lazily,so there is no speed penalty if only those attributes which are lightweightto compute are used.

left

The directorya.

right

The directoryb.

left_list

Files and subdirectories ina, filtered byhide andignore.

right_list

Files and subdirectories inb, filtered byhide andignore.

common

Files and subdirectories in botha andb.

left_only

Files and subdirectories only ina.

right_only

Files and subdirectories only inb.

common_dirs

Subdirectories in botha andb.

common_files

Files in botha andb.

common_funny

Names in botha andb, such that the type differs between thedirectories, or names for whichos.stat() reports an error.

same_files

Files which are identical in botha andb, using the class'sfile comparison operator.

diff_files

Files which are in botha andb, whose contents differ accordingto the class's file comparison operator.

funny_files

Files which are in botha andb, but could not be compared.

subdirs

A dictionary mapping names incommon_dirs todircmpinstances (or MyDirCmp instances if this instance is of type MyDirCmp, asubclass ofdircmp).

在 3.10 版的變更:Previously entries were alwaysdircmp instances. Now entriesare the same type asself, ifself is a subclass ofdircmp.

filecmp.DEFAULT_IGNORES

在 3.4 版被加入.

List of directories ignored bydircmp by default.

Here is a simplified example of using thesubdirs attribute to searchrecursively through two directories to show common different files:

>>>fromfilecmpimportdircmp>>>defprint_diff_files(dcmp):...fornameindcmp.diff_files:...print("diff_file%s found in%s and%s"%(name,dcmp.left,...dcmp.right))...forsub_dcmpindcmp.subdirs.values():...print_diff_files(sub_dcmp)...>>>dcmp=dircmp('dir1','dir2')>>>print_diff_files(dcmp)