$ git add b.txt
warning: LF will be replaced by CRLF in b.txt.
The file will have its original line endings in your working directory
Administrator@SD-20191128LXMQ MINGW64 /d/gitRepos/repo1 (master)
$ git commit -m "b.txt" b.txt
warning: LF will be replaced by CRLF in b.txt.
The file will have its original line endings in your working directory
[master 4ae6a0c] b.txt
 1 file changed, 1 insertion(+)
 create mode 100644 b.txt
Administrator@SD-20191128LXMQ MINGW64 /d/gitRepos/repo1 (master)
$ git status
On branch master
nothing to commit, working tree clean
Administrator@SD-20191128LXMQ MINGW64 /d/gitRepos/repo1 (master)
$ git rm b.txt
rm 'b.txt'
Administrator@SD-20191128LXMQ MINGW64 /d/gitRepos/repo1 (master)
$ git status
On branch master
Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
        deleted:    b.txt
Administrator@SD-20191128LXMQ MINGW64 /d/gitRepos/repo1 (master)
$ git status
On branch master
Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
        deleted:    b.txt
# 注意这里需要重新提交操作
Administrator@SD-20191128LXMQ MINGW64 /d/gitRepos/repo1 (master)
$ git commit -m "delete b.txt"
[master d39bee4] delete b.txt
 1 file changed, 1 deletion(-)
 delete mode 100644 b.txt
Administrator@SD-20191128LXMQ MINGW64 /d/gitRepos/repo1 (master)
$ git status
On branch master
nothing to commit, working tree clean

$ git add -A
warning: LF will be replaced by CRLF in a.txt.
The file will have its original line endings in your working directory
Administrator@SD-20191128LXMQ MINGW64 /d/gitRepos/repo1 (master)
$ git status
On branch master
No commits yet
Changes to be committed:
  (use "git rm --cached <file>..." to unstage)
        new file:   a.txt
Administrator@SD-20191128LXMQ MINGW64 /d/gitRepos/repo1 (master)
$ git commit -m "第一次提交 a.txt" a.txt
warning: LF will be replaced by CRLF in a.txt.
The file will have its original line endings in your working directory
[master (root-commit) 272a9cd] 第一次提交 a.txt
 1 file changed, 9 insertions(+)
 create mode 100644 a.txt
Administrator@SD-20191128LXMQ MINGW64 /d/gitRepos/repo1 (master)
$ git status
On branch master
nothing to commit, working tree clean