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Trim trailing and leading slash in bash - joining param substitutions?

I'm trying to trim a possible / from the start and end of a string in bash.

I can accomplish this via the following:

string="/this is my string/"
string=${string%/}
string=${string#/}
echo $string # "this is my string"

However, I would like to know if there's a way to join those two lines (2 + 3) to replace both at once. Is there a way to join the substitution, or is that the best I'm going to get?

Solution

  • Unfortunately there's no way to do that. However if you're sure that your string begins in / and ends in / you can trim it by ${P:M:N} format:

    string='/this is my string/'
string=${string:1:(-1)}

    Adding a check could also help but it's still two statements:

    [[ $string == /*/ ]] && string=${string:1:(-1)}

    Note: Solution is only available starting Bash 4.2.