Bdtjtk

How to understand the structure of git command?

   git remote add origin repo-url

In the code above which one is a command and which one is a parameter?

There are different command-line interpreters available on different systems, so for some of the details, the OS and/or your chosen shell matter. You mention Linux (via the linux tag), so we might assume you are using bash, dash, fish, zsh, or perhaps even tcsh or some such. These shells all vary slightly but they have a lot of things in common:

• They treat the first white-space-separated word as the command. All remaining words are arguments.




• They do what the shells call glob expansion, so that instead of programs having to interpret *.py for instance, the program just gets all the .py files as individual arguments.




• They perform variable expansion, such as replacing $HOME with your home directory.

(This is not the right place to discuss all of these details—find documentation for your particular shell, and read that, and/or read some Unix or Linux programming environment books. StackOverflow and other StackExchange sites do have plenty of specific answers about specific shell programming constructs, though.)

In any case, given the command:

git remote add origin repo-url

the shell's responsibility is to break up the five words into an argument vector: git, remote, add, origin, and repo-url. The zeroth argument¹ is the command to run, so the shell then locates this command (using $PATH) and runs it, passing all the arguments—including the command name itself—to the command.

Thus, at this point, the command is git and everything else is an argument to that command. However, the git command itself acts like a miniature, non-interactive shell: it interprets its arguments, such as remote, to figure out which of these is a command. So to Git, remote is a command, with arguments add, origin, and repo-url. Git prefixes the command with git-, then locates the git-remote command—which resides in the directory that git --exec-path will print—and runs that, with arguments add, origin, and url (and zeroth argument git-remote).

So, having passed through the git command into the git-remote command, the arguments are now just add, origin, and url (with the command name git-remote available to git-remote as the zero'th argument).

Note that the git command itself takes (and handles and therefore takes away) some command options. For instance, running:

git --work-tree=/tmp hello world

causes Git to save away the work-tree setting /tmp, then attempt to run the command git-hello with the argument world. You can write your own Git commands by writing, e.g., a git-hello program: git hello will then run your git-hello program. In any case, the --work-tree argument has vanished from the argument list at this point. (Git has stored it in an environment variable, $GIT_WORK_TREE. Environment variables are passed across exec system calls; exec is how the shell runs git and how Git runs its sub-commands.)

¹This zeroth argument is often referred to as argv[0], after the naming convention used in C language programming.

git cli book has detailed information on the git command line interface.

in your code, git remote is command and following it are the arguments.

git-remote - Manage set of tracked repositories

Manage the set of repositories ("remotes") whose branches you track.

you can find subcommands for any git command by

git help <git_command>

if you are having difficulty understanding the git CLI you can always use git GUI, which works fine too.