What's the purpose of the curly braces after a perl -e line

Question

I know some real perl basics, and I've been using this one liner to rename files:

find . -type f -exec perl -e 'rename($_,lc) for @ARGV' {} \;

The find passes a list of files to the perl one liner, which then renames them lowercase -- but whats the {} for?

Answer 1

The '{}' argument is part of the "find" command, not the "perl" command.

Per the find man page documentation, the token '{}' is replaced with the name of the current file being processed so it can be used by the target of the "exec" arguments, which are, in this case, "perl -e ...".

Answer 2

It comes from find, and will be substituted by the file(s) name found. It will execute perl like:

perl -e 'rename($_,lc) for @ARGV'filename