mjhjmtu

I desire some kind of data structure that looks similarly to a Bash function but isn't a function. A named structure to organize commands by context, that should also allow leading tabs.

This is nice when you have a file with say 20 Bash functions but have no necessity for 20 lines of function calls.

Comparison:

Bash function:

x() 
 echo "x"

x

The data structure I seek:

context 
 echo "x"

I organize the commands in such data cell similarly to how I would organize it with a function but without parameter parenthesis () and without a function call.

What is the name of such structure and how would you do it?

Notes

• The name of the structure should always come before it, in the same line, just as with a function.




• An here-document is not a solution, in this case, I desire something more minimal by means of syntax.

It's called a compound command and the syntax is

 compound-list; 

(this is an example of a compound command, other things like for loops etc. are also compound commands)

For example:

 echo 'hello'
 echo 'world'

The ; is only needed if there's no newline before the final }:

 echo 'hello'; echo 'world'; 

The commands in the ...; construct are executed in the current environment, just as for a function.

More information about this is available in the POSIX standard's description of compound commands.

There is no reason (or possibility) to name these sections as naming such a section is more or less equivalent to creating a shell function anyway. Naming a compound command would furthermore only be necessary if it's to be referred to later, which is what functions are used for.

Comments may obviously be used:

# my hello world thing

 echo 'hello'; echo 'world'

In a similar manner, a subshell may be had with

(
 echo 'hello'
 echo 'world'
)

This executes in a child environment to the current shell, and changes to variables etc. will not be reflected in the current shell.

The general syntax is

( compound-list )

Here, there is no need for a final ; before ).

As a curiosity, shell functions may use (...) in place of ...; to execute their code in a local environment:

helloworld () (
 echo 'hello'
 echo 'world'
)

This may be useful to know if one is writing a function in a sh language that does not support local variables (local or typeset in bash) and that does not need to modify the script's environment.

Are comments enough?

You could use them as follows to regroup commands and provide a name to those groups, and nothing forbids you from using indentation :

#context1
 echo "I'm in context1"
#end of context1

#context2
 echo "I'm in context2"
#end of context2

You could also regroup commands with ..., which wouldn't have any other effect in this context AFAIK :

#context1

 echo "I'm in context1"

#end of context1


 #context2
 echo "I'm in context2"
 #end of context2

If you want in addition to associate these contexts with a local scope, you could use subshells :

#context1
(
 context="context1"
 echo "I'm in $context"
)
#end of context1

( #context2
 echo "I'm in $context" #context is undefined there
 context=context2
 echo "I'm in $context"
) #end of context2

try it here