> Check if the first arg is `-h` or `--help` or `help` or just `h` or even `-help`, and in all these cases, print help text and exit.
`-h` and `--help` are fine. But `help` and `h` should only display the help if the script has subcommands (like `git`, which has `git commit` as a subcommand). Scripts that don't have subcommands should treat `h` and `help` as regular arguments -- imagine if `cp h h.bak` displayed a help message instead of copying the file named "h"!
I wouldn't encourage `-help` for displaying the help because it conflicts with the syntax for a group of single-letter options (though if `-h` displays the help, there is no legitimate reason for grouping `-h` with other options).
And ideally scripts that support both option and non-option arguments should allow `--` to separate them (e.g. `rm -- --help` removes the file called "--help"). But parsing options is complicated and probably out of scope for this article.
> If appropriate, change to the script’s directory close to the start of the script. And it’s usually always appropriate.
This is very problematic if the script accepts paths as arguments, because the user would (rightly) expect paths to be interpreted relative to the original working directory rather than the script's location. A more robust approach is to compute the script's location and store it in a variable, then explicitly prepend this variable when you want paths to be relative to the script's location.
`-h` and `--help` are fine. But `help` and `h` should only display the help if the script has subcommands (like `git`, which has `git commit` as a subcommand). Scripts that don't have subcommands should treat `h` and `help` as regular arguments -- imagine if `cp h h.bak` displayed a help message instead of copying the file named "h"!
I wouldn't encourage `-help` for displaying the help because it conflicts with the syntax for a group of single-letter options (though if `-h` displays the help, there is no legitimate reason for grouping `-h` with other options).
And ideally scripts that support both option and non-option arguments should allow `--` to separate them (e.g. `rm -- --help` removes the file called "--help"). But parsing options is complicated and probably out of scope for this article.
> If appropriate, change to the script’s directory close to the start of the script. And it’s usually always appropriate.
This is very problematic if the script accepts paths as arguments, because the user would (rightly) expect paths to be interpreted relative to the original working directory rather than the script's location. A more robust approach is to compute the script's location and store it in a variable, then explicitly prepend this variable when you want paths to be relative to the script's location.