improve bash script to add one more action if success - bash

Question

I have a bash script to find out all non empty files under some directory. currently it only print the file name if found.
I would like to add one more line to print first 32 bytes in hex format.
#!/bin/sh
files=$(find /data/ -type f ! -empty)
for f in $files;
do
if [ -f "$f" ]; then
tr -d '\000' <$f | tr -c '\000' '\n' | grep -q -m 1 ^ || echo $f
fi
done
I try to add one more "&& xxd -g 1 -l 32 $f" at the end but it doesn't work!

Answer 1

Get the first 32 chars from the file:
dd if=so.bash ibs=32 count=1 2>/dev/null | od -h
dd gets the first 32 chars
od -h prints them in hex format
You could do it with xxd as well
xxd -l 32 $f
where $f is the file
#!/bin/bash
files=$(find /data/ -type f ! -empty)
for f in $files
do
if [ -f "$f" ]; then
tr -d '\000' <"$f" | tr -c '\000' '\n' | grep -q -m 1 ^ || echo $f
xxd -l 32 "$f"
echo ""
fi
done
the echo "" is to have an empty line between each file to split the output.

Answer 2

Suggesting one line gawk script:
gawk 'BEGINFILE{print FILENAME}/[^\x00]/{system("xxd -l 32 "FILENAME;nextfile}' $(find /data/ -type f ! -empty)
gawk Explanation
BEGINFILE{print FILENAME}
BEGINFILE{ # before processing a file
print FILENAME; # print the filename
}
/[^\x00]/{system("xxd -l 32 "FILENAME);nextfile}
/[^\x00]/{ # if records contains non NULL character
system("xxd -l 32 "FILENAME); # print first 32 hex charachters
nextfile; # read next file
}

Answer 3

Every command run in bash shell returns a value that’s stored in the bash variable “$?”.
Then the command can be split as below:
#!/bin/sh
files=$(find /data/ -type f ! -empty)
for f in $files;
do
if [ -f "$f" ]; then
tr -d '\000' <$f | tr -c '\000' '\n' | grep -q -m 1 ^
if [ $? -ne 0 ]; then
echo $f
xxd -l 32 $f
fi
fi
done