将字符串作为带空格的参数传递给 bash 函数

Question

I'm trying to pass a string to a function. The string contains multiple arguments and some of the arguments may begin with multiple spaces.

#!/bin/bash
test_function() {
    echo "arg1 is: '$1'"
    echo "arg2 is: '$2'"
    echo "arg3 is: '$3'"
}

a_string="one two \"  string with spaces in front\""
result=$(test_function $a_string)
echo "$result"

Here is the output actually produced:

arg1 is: 'one'
arg2 is: 'two'
arg3 is: '"'

Here is an example of the output I am trying to achieve:

arg1 is: 'one'
arg2 is: 'two'
arg3 is: '  string with spaces in front'

How can I store arguments containing spaces in a string like this to later be passed to a function?

Although it can be done with an array, I need to first convert the string into the array values.

Answer 1

With an array.

a_string=(one two "  string with spaces in front")
result=$(test_function "${a_string[@]}")

Answer 2

bash -c may be what you're looking for (or perhaps even better, eval , as John Kugelman points out below). From the man page,

If the -c option is present, then commands are read from the first non-option argument command_string. If there are arguments after the command_string, the first argument is assigned to $0 and any remaining arguments are assigned to the positional parameters. The assignment to $0 sets the name of the shell, which is used in warning and error messages.

Basically bash -c "foo" is the same (plus a subshell) as foo . In this way we can easily insert our string as arguments.

Here it is in your example:

#!/bin/bash
test_function() {
    echo "arg1 is: '$1'"
    echo "arg2 is: '$2'"
    echo "arg3 is: '$3'"
}

a_string="one two \"  string with spaces in front\""

export -f test_function
bash -c "test_function $a_string"

(The export is necessary in this example because it's a defined function, but wouldn't be in other cases).

Output:

arg1 is: 'one'
arg2 is: 'two'
arg3 is: '  string with spaces in front'