How to view Git objects

Original: http://gitbook.liuhui998.com/7_2.html

If you don't know how git is stored before reading this article, read how Git stores objects. We can use the Cat-file command to query the information for a particular object. Note that only part of the SHA value is typed below, and you do not have to type all 40 characters:

$ git-cat-file -t 54196cc2 Commit$ git-cat-file commit 54196cc2 Tree 92b8b694ffb1675e5975148e1121810081dbdffe author J. Bruce fields <[email protected]. Fieldses. org> 1143414668 -0500 committer J. Bruce fields <[email protected]. Fieldses. org> 1143414668 -0500 Initial CommitA tree object can refer to one or more block (BLOB) objects, each of which corresponds to a file.  Further, the tree object can also refer to other tree objects, thus constituting a directory hierarchy. Each commit corresponds to a tree object. You can use Ls-tree to view the contents of the tree:$ git ls-tree 92b8b694 100644 blob 3b18e512dba79e4c8300dd08aeb37f8e728b8dad file. TXT We can see that the tree contains a file. The SHA value is a reference to the contents of the file (the translator notes that the pointer points to the corresponding block object).$ git cat-file -t 3b18e512 blobA "block" (BLOB) is the data of a file, and we can view its contents with Cat-file:

$ git cat-file blob 3b18e512 Hello WorldNotice that the data in the file is old. The initial tree is actually a snapshot of the directory state that was logged the first time it was committed. All objects are stored under the GIT directory using the SHA1 value as an index:

$ find . Git/objects/ . git/objects/ . git/objects/pack . git/objects/info . git/objects/3b . git/objects/3b/18e512dba79e4c8300dd08aeb37f8e728b8dad . git/objects/ . Git/objects/b8b694ffb1675e5975148e1121810081dbdffe . git/objects/ si. Git/objects/196cc2703dc165cbd373a65a4dcf22d50ae7f7 . Git/objects/a0 . git/objects/a0/423896973644771497bdc03eb99d5281615b51 . Git/objects/d0 . git/objects/d0/492b368b66bdabf2ac1fd8c92b39d3db916e59 . git/objects/c4 . git/objects/c4/d59f390b9cfd4318117afde11d601c1085f241 The contents of these files are actually compressed data plus a callout type and length of the header. The type can be a block (BLOB), a tree, commit (commit), or a tag (tag). The most easily found commits are head commits, which we can find in. Git/head:

$ cat . Git/HEAD ref: refs/heads/Master As you can see, the above output tells us which branch we are working on. git identifies a branch by creating a file in the. git directory (refs/heads the following file, multiple branches will have multiple files). Each file contains a committed SHA1 value, and we can use Cat-file to view the content of this submission (this is the head of the branch):

$ cat . Git/refs/heads/Master c4d59f390b9cfd4318117afde11d601c1085f241$ git cat-file -t c4d59f39 Commit$ git cat-file commit c4d59f39 Tree d0492b368b66bdabf2ac1fd8c92b39d3db916e59parent 54196cc2703dc165cbd373a65a4dcf22d50ae7f7 author J.bruce fields <[email protected].. Org> 1143418702 -< Span class= "lit" >0500 committer J. Bruce fields <[email protected]. Fieldses. org> 1143418702 -0500 Add emphasisThe tree object here points to the new state of the tree:$ git ls-tree d0492b36 100644 blob a0423896973644771497bdc03eb99d5281615b51 file. TXT $ git cat-file blob a0423896 Hello World! The parent object points to the previous commit:

$ git-cat-file commit 54196cc2 Tree 92b8b694ffb1675e5975148e1121810081dbdffe author J.bruce fields <[email protected].. Org> 1143414668 -< Span class= "lit" >0500 committer J. Bruce fields <[email protected]. Fieldses. org> 1143414668 -0500 End!

How to view Git objects