Is there a way to give curly braces to a bash script as command line arguments in linux

Question

I want to give a map-like structure as an argument to a bash script. I tried below methods, and they are working.

1. bash src.sh b:\{x:1,y:2}

2. bash src.sh b:'{x:1,y:2}' 
   "{}" also works

Above the first method somehow mess up when I use the command inside another script with possible line breaks inside the braces ( \\ ).

bash src.sh b:\{x:1,\
    y:2}

y:2} part is missing

The second method is somewhat fine but it contains the \\ inside the argument when the line break is inside quotes ''

bash src.sh b:'{x:1,\
    y:2}'

argument will be b:{a:1,\ b:2}

Why can't I give {} directly to a bash script? Is there a better way to do give {} or completely new way to give a map-like structure as above.

Answer 1

Why can't I give {} directly to a bash script? Is there a better way to do give {} or completely new way to give a map-like structure as above.

Neither { nor } is treated in a special way by bash when given as arguments to a command (unless you are unfortunate and happen to combine them to form a brace expansion or parameter expansion ). In your case, they are just plain characters in a string - but to avoid any future hazzle, consider surrounding the argument(s) with ' to avoid string interpolation.

Given this script:

for var in "$@"
do
    echo ">$var<"
done

and this input

b:\{x:1,\
    y:2}

you get this output

>b:{x:1,<
>y:2}<

The reason why the first part is in $1 and the second part is in $2 is because there are spaces in front of y so the normal argument splitting comes into play. The newline does not matter in this case (it's not a part of the string). If you give this input instead:

b:\{x:1,\
y:2}

You'll get this output:

>b:{x:1,y:2}<

If you'd like to concatenate all the arguments into one, just use "$@" :

var="$@"    # or just  var=$@