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Shell: Add documentation for functions

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AnotherTest 2020-09-13 16:20:08 +04:30 • committed by Andreas Kling
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Base/usr/share/man/man5/Shell.md
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@ -220,6 +220,37 @@ $ { for * { te $it } }&
$ disown $ disown
``` ```
##### Functions
A function is a user-defined entity that can be used as a simple command to execute a compound command, optionally with some parameters.
Such a function is defined via the syntax below:
```sh
function_name(explicitly_named_arguments...) { compound_command }
```
The function is named `function_name`, and has some explicitly named arguments `explicitly_named_arguments...`, which *must* be supplied by the caller, failure to do so will cause the command to exit with status 1.
The compound command shall be executed whenever the simple command `function_name` is executed.
This execution shall be performed in a new local frame.
Additionally, should the simple command containing the function name be in a pipeline, or requested to be run in the background, this execution shall be moved to a subshell; naturally, in such a case any changes to the shell state (such as variables, aliases, etc) shall not be leaked to the parent shell process.
The passed arguments shall be stored in the special variables `*` and `ARGV`, and the explicitly named arguments shall be set, in order, from the first passed argument onwards.
The exit status of a function simple command shall be the exit status of the last command executed within the command, or 0 if the function has no commands.
The declaration is *not* a command, and will not alter the exit status.
###### Examples
```sh
fn(a b c) {
echo $a $b $c \( $* \)
}
$ fn 1 2 3 4
# 1 2 3 ( 1 2 3 4 )
```
## Formal Grammar ## Formal Grammar
### Shell Grammar ### Shell Grammar
@ -229,8 +260,11 @@ toplevel :: sequence?
sequence :: variable_decls? or_logical_sequence terminator sequence sequence :: variable_decls? or_logical_sequence terminator sequence
| variable_decls? or_logical_sequence '&' sequence | variable_decls? or_logical_sequence '&' sequence
| variable_decls? or_logical_sequence | variable_decls? or_logical_sequence
| variable_decls? function_decl (terminator sequence)?
| variable_decls? terminator sequence | variable_decls? terminator sequence
function_decl :: identifier '(' (ws* identifier)* ')' ws* '{' toplevel '}'
or_logical_sequence :: and_logical_sequence '|' '|' and_logical_sequence or_logical_sequence :: and_logical_sequence '|' '|' and_logical_sequence
| and_logical_sequence | and_logical_sequence