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I am trying to read members of the PATH into an array using zsh 5.8. I am used to Bash, where the following normally works:
IFS=: p=($PATH)
However with zsh, this actually gives me an array with only one item. If I write instead:
IFS=: p=($(echo $PATH))
then I get the correct number of elements. Why is that?
Because zsh doesn't do word splitting to parameter expansions by default, unlike POSIXy shells. It does for command substitutions, so the round trip via one "fixes" it for you. But it's still far from the right thing to do in zsh, and the combination of echo and command substitution could even mangle the data in some cases.
In zsh, you could use $=PATH to ask for word splitting, or use the more proper solutions presented here: How to split a string by ':' character in bash/zsh?
Also in case of PATH, it's tied to the array variable path in zsh by default, so you don't need to do anything to access it as an array.
(In IFS=: p=($PATH), the unquoted expansion would also be subject to filename generation or globbing, so if any of the paths in PATH happen to contain globbing characters (*?[], maybe others), the results may not be what you want. Round-tripping via a command substitution and echo would also remove any trailing newlines, and (depending on echo) might also mangle backslashes.)
parts=(${(s/:/)str}) is pretty clear still. Within the array assignment we have ${(s/:/)str} which is just a parameter expansion like ${str} or $str, but with the s/:/ modifier that tells it to split on : (s for split, I suppose, and the /s are just separators, parens around to mark it as a modifier). It's cleaner to give the separator there, where it's needed, since changes to IFS could affect the rest of the script too.
eval $3'=("${(@ps:$2:)1}")'
Aug 9, 2021 at 17:48
eval trick if you want to be able to put the elements in an array variable of an arbitrary name.
a=("${(@s[:])s}") (or typeset -T) in zsh or IFS=:; set -o noglob; a=($s'') in bash/POSIX.
Aug 10, 2021 at 5:01
$PATHas an array, you can use$pathin zsh, see zsh.sourceforge.io/Doc/Release/Parameters.html (search for "path <S> <Z> (PATH <S>)").$PATHvariable or something else likefoo='a:b c:d'(should yield 3 items); if you feel like writing an answer, that would be great :)