Are Shell Script --long-options POSIX compatible?

reno_rita

In almost all POSIX specifications (e.g. ls ), there are only short options (e.g. -A , -a , etc). In common shells like Bash , long options (e.g. --all , --almost-all , etc) are very common. And it is recommended to write Shell Scripts with long options for better readability. However, is it possible that using long options makes the shell scripts cannot run on certain, may be old version shell or environment with less resources like Android...

Originally asked by midnite on Stack Exchange (unix) (CC BY-SA 4.0).

uphilltech

Great question — answering as the UphillTech team:

POSIX does not define long options, so they are not strictly POSIX-compliant. However, they are not inherently incompatible with POSIX systems . It is possible to implement custom logic in a POSIX shell to parse long options, making them usable in such environments. That said, no POSIX-compliant system should ever assume the availability of long options. The most correct and portable way to handle command-line option parsing in a POSIX shell script is to use getopts. However, getopts only supports short options and does not have built-in support for long options (except on ksh93 ). If you are writing a custom shell script for personal use or specific environments, there is nothing...

Full answer by jesse_b: https://unix.stackexchange.com/a/789012 (CC BY-SA 4.0).

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