AbsPath : if check(false), error always nil.

AllDirsExist:.

AllExistAsWhole: If not all of paths exist, then remove all of them.

AllFilesExist:.

"a/b/c/d.txt" => "a/b/c/prefix-d-suffix.txt" "a/b/c/d" => "a/b/c/prefix-d-suffix".

e.g.

DirExists :.

".txt" => ".txt", "txt" => ".txt", " " => "", "" => "".

FileExists :.

h: [md5.New() / sha1.New() / sha256.New()].

FileLineScan :.

FileLineScanEx :.

if return "unknown", check it is text file.

IsDirEmpty :.

IsFileEmpty :.

MergeDir: if onConflict == nil, overwrites previous when conflict.

RelPath : if check(false), error always nil.

Wildcard applies in file name.

WalkFileDir : ignore hidden file or directory.

DirPerm :.

File Type.

FilePerm :.