basename problems with xargs/find and command substitution

[Trev Peterson]

Binary package hint: coreutils

basename does not return the correct basename when executed using command substitution from find (-exec) or xargs (dirname does).

works using find -exec directly
$ find . -type f -iname '*.jpg' -exec basename {} \;
Patio before.JPG
Patio1-1.JPG
Patio1-2.JPG
Patio1-3.JPG

does not work using find -exec using command substitution
$ find . -type f -iname '*.jpg' -exec printf "$( basename {} ) \n" \;
./Patio before.JPG
./Patio1-1.JPG
./Patio1-2.JPG
./Patio1-3.JPG

dirname works using find -exec using command substitution
$ find . -type f -iname '*.jpg' -exec printf "$( dirname {} ) \n" \;
.
.
.
.

works direct from xargs
printf "./Patio1-1.JPG\n" | xargs -0 -I{} basename {}
Patio1-1.JPG

does not work from xargs with command substitution (again dirname does)
printf "./Patio1-1.JPG\n" | xargs -0 -I{} printf " fullname:{} basename:$( basename "{}" ) dirname:$( dirname "{}" )\n"
 fullname:./Patio1-1.JPG
 basename:./Patio1-1.JPG
 dirname:.

System information:
9.10 karmic
ii findutils 4.4.2-1 utilities for finding files--find, xargs
ii coreutils 7.4-2ubuntu1 The GNU core utilities
uname -a
Linux aegir 2.6.31-19-generic #56-Ubuntu SMP Thu Jan 28 02:39:34 UTC 2010 x86_64 GNU/Linux

$ which basename
/usr/bin/basename

Let me know if you need anything else to help with this. Thanks,

[C de-Avillez (hggdh2)]

Thank you for opening this bug and helping make Ubuntu better.

This had me stumped for a while, and I queried about it (all the while with this firm believe the answer was staring at me). And I did get an answer. Indeed, this is not a bug, but normal shell processing...

Here's the deal: when you have a $(...) construct, the contents are passed to the shell. Shell variables are resolved as usual, and the rest is left as is. It happens that '{}' is *not* a shell variable -- so it is left as is.

*When* the shell returns... then '{}' gets to be magic again, and -exec processing replaces it by the correct value.

This can be easily seen by running the following:

   echo find . -type f -exec echo $(basename {}) \;

As such, marking Invalid.

p.s. And I *knew* I was missing the answer ;-) -- Thank you, Bob!