[kwlug-disc] Reminder: bash's find has option -exec

[Ron]

Mikalai Birukou via kwlug-disc wrote on 2025-11-07 13:46:

> As a reminder, bash's find has option -exec, that let's you do
> something during find's iteration.
That's one of my favourite options with `find`.


It should be noted that `find ... -exec ...` requires a semi-colon at 
the end. But, that semi-colon needs to be escaped like this: \;


Unless... one doesn't want the default behaviour of whatever is being 
exec'd to run *once per found item*.

If one would prefer everything found to be passed at once, finish the 
statement with \+


Unless... there's a whole bunch of stuff being found, then it gets 
buffered and passed to the -exec'd program when the buffer is full, not 
just when the `find` is done.


How big is the buffer? Who knows, good luck.


Someone wanted to find the newest or oldest file on a failing disk.

I suggested something like:

find $mount_point -type f -exec ls -lta {} \+ | head -n 1


It worked perfectly on some test folders.

One an entire disk though?  Too many entries returned, got sorted 
chunks, completely failed.

I think the buffer consisted of about 300 entries, out of thousands.



Anyway, there's a thread about "find newest and oldest items on a disk" 
with some of the craziest mailing list replies I've ever seen (makes me 
rethink my skepticism about full moons) starting here:

https://mail.ale.org/pipermail/ale/2025-April/166848.html


Staggeringly incorrect answers abound, to the point where it's fun to 
see "what will they come up with next?"



My final answer:

find $mount_point -printf "%TY-%Tm-%Td %TH:%TM:%TS %p\0"  \
     | sort --zero-terminated \
     | tr '\0' '\n'           \
     | sed -n -e 1p -e '$p'

Probably contains subtle errors still.