Hello,
I think you did things very,very well, thank you for this.
Here is some feedback:
1 - aliases are not required for me, but It could still be a worthwile
feature for others, and it's a requirement for you.
2 - this feels ok for me, since this is generally a better behaviour of
the shell parser that would benefit other applications, I believe.
3 - partial implementation does not feel blocking for me. yes, double
quotes are more complex. I think there is already a config variable for
shell var extension? Can you plan your code to slightly facilitate
future extensions if choices are to be made?
4 - for backwards compatibility, this feature should not be on by
default, but it is a good general improvement of the shell, so with a
notification in git logs, I could see this on by default. No strong
opinion on this point.
5 - for this point, I would say aliases need to be per session, since
global aliases with multiple shells could be security issues or just
annoyance when you dont expect them to be there. Thats how it's made in
linux shells, right? Does posix say something about shells?
I hope more people share their opinions soon.
Thank you again for the time you took to write this.
Sebastien
Le 09/03/2023 à 11:14, Ville Juven a écrit :
Hi all,
I'm in the process of writing support for shell aliases into NSH, but since
the shell is the front end for NuttX I decided to make a post here for
opinions on this matter and to open discussion for requirements, mostly to
prevent unexpected regression issues that might arise from this.
1. Are shell aliases seen as something useful in the community ? I need
them for a project of mine which is the reason I started implementing
support but I'd like to know if they are seen as useful whatsoever by
others.
2. To properly support aliases, the shell parser needs to support single
quotes and double quotes. This support will generate a bit of extra code
into the parser, is this seen as OK ?
alias foo='bar baz'
alias foo="bar $baz"
In both cases, the parser stops on the first delimiter (whitespace) even
though it is quoted.
3. I will implement support for *single quotes* as this is a simple case
but not for double quotes as the rules are more complex (need to perform
variable expansions etc). Is this seen as a blocker / fatal issue?
4. I added a Kconfig option to turn alias support on/off, what should the
default state of this option be ? Currently it is defined as follows:
config NSH_ALIAS
bool "Enable alias support"
default !DEFAULT_SMALL
I noticed that many of the shell features are flagged behind DEFAULT_SMALL.
Also the alias amount is configurable.
5. Currently aliases are implemented globally i.e. every shell shares the
same aliases, is this seen as a problem or should I make the aliases stick
to a shell session only ?
This is my first time posting on this board, so apologies if I did
something improper.
Br, Ville Juven
