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Comment by snissn | Hacker News Reader

Could you explain what this line of code does?

    ssh -t user@example.com "$(< ./my-setup-script.sh)"

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It's a weird way of writing

  ssh -t user@example.com /bin/bash < my-setup-script.sh

That is, take the contents of the local file 'my-setup-script.sh' and run them as commands on example.com as the 'user' user (using SSH to authenticate the user & transport the commands).

But that might fail half-way through the file, and the other one is all or nothing, might just report "argument list too long".

> might fail half-way through the file

Oh, while transferring!

  ssh -t user@example.org bash <( echo "function do_it() {"; cat my-setup-script.sh; echo -e "}\ndo_it" )

No argument limits to worry about, no quoting hassles.

Looks like a fancier version of

        ssh -t user@example.com "$(cat ./my-setup-script.sh)"

I'll have to file this away myself!

Not fancier, just a bash-ism that may not work with some other shells.

[bash] https://www.gnu.org/software/bash/manual/html_node/Command-S...

[posix] http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3...

It allows you to run a local shell script on the server via ssh, using bash command substitution - the "$(<" part. The -t option (force tty) executes the script in an interactive session - without it stuff like password prompts won't work (if I remember correctly).

it runs the local contents of ./my-setup-script.sh on the remote server in a way that escapes all the special characters so they don't do unexpected things.

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