How does `find . -name *foo*` work?

Question

I thought the wildcard * in the command find . -name *foo* is replaced by bash, and yet the command works unless *foo* matches something in the current directory, then it doesn't. It's confusing.

Answer 1

If bash can't find a match, it passes the literal string to the application with *s unexpanded. For example:

$ ls
foo

$ cat /tmp/test
echo $1

$ /tmp/test *foo*
foo

$ /tmp/test *bar*
*bar*

bash expanded *foo* because it matched, but passed *bar* directly because it didn't. The nullglob option will tell bash to resolve non-matching patterns to the empty string instead:

$ shopt -s nullglob
$ /tmp/test *bar*

$

Answer 2

If you want find to get the unexpanded string, then you could quote it or protect the wildcards with backslashes.

$ ls
foo

$ cat /tmp/test
echo $1

$ /tmp/test '*foo*'
*foo*

$ /tmp/test \*foo\*
*foo*