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diff --git a/source/blog/2015-07-15-zsh-save-stdout-stderr-and-return-value-of-command-to-different-variables-without-temp-file.md b/source/blog/2015-07-15-zsh-save-stdout-stderr-and-return-value-of-command-to-different-variables-without-temp-file.md new file mode 100644 index 00000000..d27a3002 --- /dev/null +++ b/source/blog/2015-07-15-zsh-save-stdout-stderr-and-return-value-of-command-to-different-variables-without-temp-file.md @@ -0,0 +1,33 @@ +--- +title: "Zsh: save stdout, stderr, and return value of command to different variables (without temp file)" +date: 2015-07-15T09:21:47-07:00 +date-display: July 15, 2015 +--- +This is something worth sharing. The idea was based on [this SO answer](http://stackoverflow.com/a/18086548/1944784), and I cooked up this particular implementation to remove potential race conditions, with input from Mathias Fredriksson[^1]. See [mafredri/zsh-async#1](https://github.com/mafredri/zsh-async/issues/1), and in particular [this comment](https://github.com/mafredri/zsh-async/issues/1#issuecomment-121468958) for explanation. + +```zsh +# The following construct evaluates "$@" and saves output on stdout in the +# parameter stdout, output on stderr in the parameter stderr, and return value +# in the parameter return. +# +# The idea was based on http://stackoverflow.com/a/18086548/1944784, but this +# implementation is completely race-condition-free. The implementation was +# refined during my exchange with Mathias Fredriksson @mafredri, in +# https://github.com/mafredri/zsh-async/issues/1. See mainly +# https://github.com/mafredri/zsh-async/issues/1#issuecomment-121468958, where +# the advantage of this implementation is explained. + +unset stdout stderr ret +eval " +$( + { + stdout=$(eval "$@") + ret=$? + typeset -p stdout ret + } 2> >(stderr=$(cat); typeset -p stderr) +)" +``` + +Also available as [a gist](https://gist.github.com/zmwangx/efababea6258cedea07a). + +[^1]: Mathias ([\@mafredri](https://github.com/mafredri)) is the author of the lovely [zsh-async](https://github.com/mafredri/zsh-async) library, and a maintainer of [sindresorhus/pure](https://github.com/sindresorhus/pure). He forever revolutionalized [my prompt](https://github.com/zmwangx/prezto/blob/master/modules/prompt/functions/prompt_zmwangx_setup). |