How to force bash/zsh to evaluate parameter as multiple arguments when applied to a command

I am trying to run a program like this:

$CMD $ARGS

where $ARGS is a set of arguments with spaces. However, zsh appears to be handing off the contents of $ARGS as a single argument to the executable. Here is a specific example:

$export ARGS="localhost -p22"
$ssh $ARGS
ssh: Could not resolve hostname localhost -p22: Name or service not known

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Is there a bash or zsh flag that controls this behavior?

Note that when I put this type of command in a $!/bin/sh script, it performs as expected.

Thanks,

SetJmp

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In zsh it's easy:

Use cmd ${=ARGS} to split $ARGS into separate arguments by word (split on whitespace).

Use cmd ${(f)ARGS} to split $ARGS into separate arguments by line (split on newlines but not spaces/tabs).

As others have mentioned, setting SH_WORD_SPLIT makes word splitting happen by default, but before you do that in zsh, cf. http://zsh.sourceforge.net/FAQ/zshfaq03.html for an explanation as to why whitespace splitting is not enabled by default.

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If you want to have a string variable (there are also arrays) be split into words before passing to a command, use $=VAR. There is also an option (shwordsplit if I am not mistaking) that will make any command $VAR act like command $=VAR, but I suggest not to set it: I find it very inconvenient to type things like command "$VAR" (zsh: command $VAR) and command "${ARRAY[@]}" (zsh: command $ARRAY).

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It will work if you use eval $CMD $ARGS.