Re: basename is not working as expected if invoked in `` inside a find subcommand

[Paul Jarc]

"Andreas R." <newsgroups2005@geekmail.de> wrote:
>   find dir1 -type f -exec sh -c 'echo "{}" dir2/"`basename "{}"`"' \;
> it works, but I still don't understand completely why it works.

Actually, it still won't work in some cases.  If a filename contains a
double quote, like 'foo" "bar', the shell will see this command for
-c:
  echo "foo" "bar" dir2/"`basename "foo" "bar"`"
which isn't what you want.  This will handle any flename properly:
  find dir1 -exec sh -c 'diff -q "$0" dir2/"`basename "$0"`"' {} \;

The difference here is that {} is substituted by find, before sh is
invoked, so if {} appears within the -c command, sh will interpret any
special characters in the filename as shell syntax, not as part of the
filename.  Keeping {} as a separate argument to sh, and referring to
it as a variable from within the command, prevents any such problems.

> And where do you learn such tricks from? :)

Experience, mostly.


paul