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In that fun way that shells are, for bare redirection it depends.

In bash/ksh, it matches frou_dh's explanation. In zsh, it depends on how you've set the various *NULLCMD options and parameters. In csh, it is an error.

Even in zsh, when configured to behave like `cat file` it still doesn't quite do that as it won't concatenate files as it only passes the first shell word following the `<` to `cat`(or whatever you've set NULLCMD to). Guess that means you could be evil by making a wrapper that allows weird Unicode separators to pass multiple files in one word to get the concatenation back ;)

1 comments

Because I hate myself I guess, I use zsh as my interactive shell, but generally write scripts for bash. The latter is mostly for portability (although with Macs stuck on 3.2 unless updated manually, that’s less true over time), and also because shellcheck doesn’t work on zsh.

This means I get to remember an increasingly unfortunate amount of differences. I’ll add this one to the pile, thanks.

I've mentioned this in previous posts here, but I write zsh scripts utilising all the extras that zsh gives(alternate form syntax, extensive extended globbing, zsh module support for extra functionality). It sounds stupid but it makes it really obvious that what you're writing isn't a generic shell script, and you can forgo having to think too much about whether something will work in modern bash, or MacOS pre-GPL3 bash, or {b,d,k,z}ash as /bin/sh symlink.

I definitely get the argument about shellcheck though, it would be nice if it supported zsh.

That’s fair. I wrote a script at work recently for zsh that relied on some of its niceties, like glob qualifiers. The reason for using zsh was we only use Macs, so it was reasonable to assume everyone would have a decently modern version of zsh available.

It definitely looks foreign, but then, so does parameter substitution in bash or zsh. There are shell scripts, and then there are those that make you break out the man pages to figure out what they’re doing.