How can I check if a file exists in ASM via shell script?

Products: Oracle 19c EE, RAC, ASM, OEL Linux 8

I am trying to write a shell script that loops through our CDBs on a given host and copies the wallet files from ASM to a local filesystem for an additional backup.

Not all of our databases use TDE, so I'm trying to execute a check to see if the wallet file exists before executing the line to make the file copy.

If this was a normal filesystem, I could use something like:

if [ -f /u01/TESTCDB/tde/ewallet.p12 ]; then
echo "file exists"
else
echo "file does not exist"
fi

However, I obviously can't put an ASM path in there, such as: