How do I tar a directory of files and folders without including the directory itself?

I typically do:

tar -czvf my_directory.tar.gz my_directory

What if I just want to include everything (including any hidden system files) in my_directory, but not the directory itself? I don't want:

my_directory
   --- my_file
   --- my_file
   --- my_file

I want:

my_file
my_file
my_file

Use the -C switch of tar:

tar -czvf my_directory.tar.gz -C my_directory .

The -C my_directory tells tar to change the current directory to my_directory, and then . means "add the entire current directory" (including hidden files and sub-directories).

Make sure you do -C my_directory before you do . or else you'll get the files in the current directory.

cd my_directory/ && tar -zcvf ../my_dir.tgz . && cd - 

should do the job in one line. It works well for hidden files as well. "*" doesn't expand hidden files by path name expansion at least in bash. Below is my experiment:

$ mkdir my_directory
$ touch my_directory/file1
$ touch my_directory/file2
$ touch my_directory/.hiddenfile1
$ touch my_directory/.hiddenfile2
$ cd my_directory/ && tar -zcvf ../my_dir.tgz . && cd ..
./
./file1
./file2
./.hiddenfile1
./.hiddenfile2
$ tar ztf my_dir.tgz
./
./file1
./file2
./.hiddenfile1
./.hiddenfile2

You can also create archive as usual and extract it with:

tar --strip-components 1 -xvf my_directory.tar.gz

Have a look at --transform/--xform, it gives you the opportunity to massage the file name as the file is added to the archive:

% mkdir my_directory
% touch my_directory/file1
% touch my_directory/file2
% touch my_directory/.hiddenfile1
% touch my_directory/.hiddenfile2
% tar -v -c -f my_dir.tgz --xform='s,my_directory/,,' $(find my_directory -type f)
my_directory/file2
my_directory/.hiddenfile1
my_directory/.hiddenfile2
my_directory/file1
% tar -t -f my_dir.tgz 
file2
.hiddenfile1
.hiddenfile2
file1

Transform expression is similar to that of sed, and we can use separators other than / (, in the above example).
https://www.gnu.org/software/tar/manual/html_section/tar_52.html