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I have a variable, say $X, that contains a command, and the command has quoted arguments with spaces, let's say <<echo "A B">>. Now how do I execute it? If I do
by jcranmer 2y ago
I have a variable, say $X, that contains a command, and the command has quoted arguments with spaces, let's say <<echo "A B">>. Now how do I execute it? If I do $X, the result <<"A B">>, not <<A B>>. If I do "$X", it fails, because there's no filename <<echo "A B">> to execute.
In a program with proper arrays, I can instead parse X to the strings ["echo", "A B"], and then run execve to run ["echo", "A B"] without any issues. And adding another argument to make ["echo", "A B", "C"] is damn trivial.
No, bash doesn't handle arguments with spaces just fine. If you do the basic, obvious way to do things, things break, and you're expected to know magic invocations to do the right thing to handle potential spaces.
- PhilipRoman 2y agoI see your point, but I still have to disagree. Your task would be inherently complicated for any language - imagine trying to properly add another argument to a function call written in python. In fact it has nothing to do with spaces in arguments, but rather re-parsing strings as shell commands which is always a tricky task. >In a program with proper arrays, I can instead parse X to the strings Well, if I were to write it in Java or Javascript, both of which have excellent support for arrays (the shell does as well, actually - via "set"), it still wouldn't get me an inch closer to achieving the goal. It seems to me that the real problem is lack of a first-class shell grammar parser, which affects most languages, not just the shell itself. Python just happens to have a shell grammar parser that is shipped with the installation.
- databasher 2y agoBash handles spaces just fine. # store the command in an array X=(echo "A B") # execute the command "${X[@]}" Yields: A B