using -exec vs. using xargs with the locate command in linux

Question

This is a little mystery regarding the difference between -exec {} and xargs that I'm trying to understand. I would appreciate any guidance on this. As background, I've just learned about the "locate" command and I successfully created a database ~/.u.db of a network drive using this command (this is in Windows WSL, by the way):

$ updatedb -l 0 -o ~/.u.db -U /mnt/u

I'm trying to use it to find all .m files from my current working directory and display the detailed file information. Normally I use the "find" command like this:

$ find . -type f -name '*.m' -exec ls -l \{\} \;

which successfully gives me a list of .m files with their file properties like this:

{all the file info} ./{relative path}/filename1.m
{all the file info} ./{relative path}/filename2.m

when I try to run the locate command in a similar manner I get an error.

$ locate -d ~/.u.db "$PWD*/*.m" -exec -ls -l \{\} \;
locate: invalid option -- 'x'

Just for reference, this works properly (without the extra file info that I'm looking for):

$ locate -d ~/.u.db "$PWD*/*.m"

/{absolute path}/filename1.m
/{absolute path}/filename2.m

I found that I can use xargs like this successfully:

$ locate -d ~/.u.db "$PWD*/*.m" | xargs ls -l

{all the file info} /{absolute path}/filename1.m
{all the file info} /{absolute path}/filename2.m

I'm just trying to understand why I should use xargs in this case and not -exec {}. I would appreciate any insight into the difference in behavior.

Answer 1

I’m not sure how much this varies, but on the Linuxes I have at hand — both running Debian derivatives — the locate command does not have an -exec switch. They all use the GNU version of locate, which follows the GNU convention that long options are introduced with -- and short options with -, and that short options can be combined if they don’t take arguments. In other words, -exec is eqivalent to -e -x -e -c, which is why it complains about an invalid -x switch.