tar package when removing the directory prefix

Remove directory prefix tar package

Explanation

Example: existing directory structure shown below.

# tree /a
/a
└── b
    └── c
        ├── hello
        └── hello.md5sum

Normally packed files in the directory c

压缩
# tar cf /opt/test.tar /a/b/c/hello /a/b/c/hello.md5sum 

解压
# tar xf test.tar 
# ls
a  test.tar
# tree /opt/a/
/opt/a/
└── b
    └── c
        ├── hello
        └── hello.md5sum

As described above, under normal circumstances the compressed file in the default directory of the directory structure packing tape, until the last layer of the file needs to be packaged.
Then only the last layer of compressed files how to package and not to bring any directory or directory is not needed it a few levels?

Method to realize

A, cp

Cp command, files are copied to the target path first, and then packaged.

# cp /a/b/c/* /opt/ && cd /opt && tar cf /opt/test2.tar ./hello ./hello.md5sum 

Second, use the "--transform"

parameter: --transform s=xxx/==

# tar cvf /trans/testfile2.tar.gz --transform s=a/b/c/== ./a/b/c/hello ./a/b/c/hello.md5sum

Explains: "s = a / b / c / ==" indicates a directory omitted, it is behind all the files to be packaged

# tar xf testfile2.tar.gz
# ls
hello  hello.md5sum

These are by --transform packaged files without directory