git 的 cat-file 命令用法
命令选项
git cat-file Provide content or type and size information for repository objects.
git cat-file 命令显示版本库对象的内容、类型及大小信息。
object
The name of the object to show. For a more complete list of ways to spell object names, see the “SPECIFYING REVISIONS” section in gitrevisions(7).
-t
Instead of the content, show the object type identified by object.
显示对象的类型。
-s
Instead of the content, show the object size identified by object.
显示对象的大小。
-e
Suppress all output; instead exit with zero status if object exists and is a valid object.
如果对象存在且有效，命令结束状态返回值为 0 。
-p
Pretty-print the contents of object based on its type.
根据对象的类型，以优雅的方式显式对象内容。
type
Typically this matches the real type of object but asking for a type that can trivially be dereferenced from the given object is also permitted. An example is to ask for a “tree” with object being a commit object that contains it, or to ask for a “blob” with object being a tag object that points at it.
用法示例
sha1sum 命令生成字符串 “Git” 的哈稀值：
printf Git | sha1sum生成 HEAD 对象的哈稀值：
(printf "%s %d\000" `git cat-file -t HEAD` `git cat-file -s HEAD`; git cat-file -p HEAD) | sha1sum