filesystem – How to safely clean up resource fork files?

The dot_clean operations can depend on the file system. I will try to illustrate this through examples. Basicaly, the following will be shown.

• The find . -type f -iname '._*' -exec rm '{}' \; command does the same thing as the dot_clean -m --keep=native . command, which is to remove ._* files.
• The dot_clean -m . command also removes ._* files, but can also transfer information before removing the files.

Initial Conditions

The ls command output below shows the contains of four volumes which are formatted as FAT32, APFS, ExFAT and JHFS+. The data fork of the hi.txt file in each volume is the same. The same is true for the ._bye.txt and ._hi.txt files in each volume. All previously existing bye.txt files have been removed.

davidanderson@Snapper /Volumes % ls -l@OeA /Volumes/MYFAT32 /Volumes/MyAPFS /Volumes/MyExFAT /Volumes/MyJHFS+   
/Volumes/MYFAT32:
total 32
-rwxrwxrwx  1 davidanderson  staff  hidden 4096 Nov 17 17:04 ._bye.txt
-rwxrwxrwx  1 davidanderson  staff  hidden 4096 Nov 17 17:02 ._hi.txt
drwxrwxrwx  1 davidanderson  staff  hidden 4096 Nov 17 18:49 .fseventsd
-rwxrwxrwx@ 1 davidanderson  staff  -        10 Nov 17 17:02 hi.txt
    com.apple.TextEncoding    15 
    com.apple.lastuseddate#PS     16 
    com.apple.metadata:kMDLabel_df4faouox2jis4jyu5u6pu7qnu    89 

/Volumes/MyAPFS:
total 24
-rwxrwxrwx  1 davidanderson  staff  - 4096 Nov 17 17:04 ._bye.txt
-rwxrwxrwx  1 davidanderson  staff  - 4096 Nov 17 17:02 ._hi.txt
drwxrwxrwx  7 davidanderson  staff  -  224 Nov 17 17:17 .fseventsd
-rwxrwxrwx  1 davidanderson  staff  -   10 Nov 17 17:02 hi.txt

/Volumes/MyExFAT:
total 256
-rwxrwxrwx  1 davidanderson  staff  hidden  4096 Nov 17 17:04 ._bye.txt
-rwxrwxrwx  1 davidanderson  staff  hidden  4096 Nov 17 17:02 ._hi.txt
drwxrwxrwx  1 davidanderson  staff  hidden 32768 Nov 17 18:49 .fseventsd
-rwxrwxrwx@ 1 davidanderson  staff  -         10 Nov 17 17:02 hi.txt
    com.apple.TextEncoding     15 
    com.apple.lastuseddate#PS      16 
    com.apple.metadata:kMDLabel_df4faouox2jis4jyu5u6pu7qnu     89 

/Volumes/MyJHFS+:
total 24
-rwxrwxrwx  1 davidanderson  staff  - 4096 Nov 17 17:04 ._bye.txt
-rwxrwxrwx  1 davidanderson  staff  - 4096 Nov 17 17:02 ._hi.txt
drwxrwxrwx  7 davidanderson  staff  -  238 Nov 17 17:17 .fseventsd
-rwxrwxrwx  1 davidanderson  staff  -   10 Nov 17 17:02 hi.txt

Note the following:

• The hi.txt file in the FAT32 and ExFAT volumes has extended attributes which are stored in the ._hi.txt file.
• The hi.txt file in the APFS and JHFS+ volumes has no extended attributes. The extended attributes, which are stored in the ._hi.txt file, are ignored.

Case 1: Use of find . -type f -iname '._*' -exec rm '{}' \;

Below the find . -type f -iname '._*' -exec rm '{}' \; command was modified to act on the four volumes as given in the Initial Conditions section. The results are shown below.

davidanderson@Snapper /Volumes % find /Volumes/MYFAT32 /Volumes/MyAPFS /Volumes/MyExFAT /Volumes/MyJHFS+ -type f -iname '._*' -exec rm '{}' \;
davidanderson@Snapper /Volumes % ls -l@OeA /Volumes/MYFAT32 /Volumes/MyAPFS /Volumes/MyExFAT /Volumes/MyJHFS+
/Volumes/MYFAT32:
total 16
drwxrwxrwx  1 davidanderson  staff  hidden 4096 Nov 17 18:49 .fseventsd
-rwxrwxrwx  1 davidanderson  staff  -        10 Nov 17 17:02 hi.txt

/Volumes/MyAPFS:
total 8
drwxrwxrwx  7 davidanderson  staff  - 224 Nov 17 17:17 .fseventsd
-rwxrwxrwx  1 davidanderson  staff  -  10 Nov 17 17:02 hi.txt

/Volumes/MyExFAT:
total 128
drwxrwxrwx  1 davidanderson  staff  hidden 32768 Nov 17 18:49 .fseventsd
-rwxrwxrwx  1 davidanderson  staff  -         10 Nov 17 17:02 hi.txt

/Volumes/MyJHFS+:
total 8
drwxrwxrwx  7 davidanderson  staff  - 238 Nov 17 17:17 .fseventsd
-rwxrwxrwx  1 davidanderson  staff  -  10 Nov 17 17:02 hi.txt

Note the following:

• All ._* files have been removed.
• None of the hi.txt files have extended attributes.

Case 2: Use of dot_clean -m .

Below the dot_clean -m . command was modified to act on the four volumes as given in the Initial Conditions section. The results are shown below.

davidanderson@Snapper /Volumes % dot_clean -m /Volumes/MYFAT32 /Volum/MyAPFS /Volumes/MyExFAT /Volumes/MyJHFS+
davidanderson@Snapper /Volumes % ls -l@OeA /Volumes/MYFAT32 /Volumes/MyAPFS /Volumes/MyExFAT /Volumes/MyJHFS+
/Volumes/MYFAT32:
total 16
drwxrwxrwx  1 davidanderson  staff  hidden 4096 Nov 17 19:32 .fseventsd
-rwxrwxrwx  1 davidanderson  staff  -        10 Nov 17 17:02 hi.txt

/Volumes/MyAPFS:
total 16
drwxrwxrwx  7 davidanderson  staff  - 224 Nov 17 17:17 .fseventsd
-rwxrwxrwx@ 1 davidanderson  staff  -  10 Nov 17 17:02 hi.txt
    com.apple.ResourceFork  286 
    com.apple.TextEncoding   15 
    com.apple.lastuseddate#PS    16 
    com.apple.metadata:kMDLabel_df4faouox2jis4jyu5u6pu7qnu   89 

/Volumes/MyExFAT:
total 128
drwxrwxrwx  1 davidanderson  staff  hidden 32768 Nov 17 19:32 .fseventsd
-rwxrwxrwx  1 davidanderson  staff  -         10 Nov 17 17:02 hi.txt

/Volumes/MyJHFS+:
total 16
drwxrwxrwx  7 davidanderson  staff  - 238 Nov 17 17:17 .fseventsd
-rwxrwxrwx@ 1 davidanderson  staff  -  10 Nov 17 17:02 hi.txt
    com.apple.ResourceFork  286 
    com.apple.TextEncoding   15 
    com.apple.lastuseddate#PS    16 
    com.apple.metadata:kMDLabel_df4faouox2jis4jyu5u6pu7qnu   89 

Note the following:

• All ._* files have been removed.
• The hi.txt file in the FAT32 and ExFAT volumes has no extended attributes.
• The hi.txt file in the APFS and JHFS+ volumes has extended attributes. The extended attributes were copied from the ._hi.txt file before the ._hi.txt file was removed.

Case 3: Use of dot_clean -m --keep=native .

Below the dot_clean -m --keep=native . command was modified to act on the four volumes as given in the Initial Conditions section. The results are shown below.

davidanderson@Snapper /Volumes % dot_clean -m --keep=native /Volumes/MYFAT32 /Volumes/MyAPFS /Volumes/MyExFAT /Volumes/MyJHFS+
davidanderson@Snapper /Volumes % ls -l@OeA /Volumes/MYFAT32 /Volumes/MyAPFS /Volumes/MyExFAT /Volumes/MyJHFS+                
/Volumes/MYFAT32:
total 16
drwxrwxrwx  1 davidanderson  staff  hidden 4096 Nov 17 19:37 .fseventsd
-rwxrwxrwx  1 davidanderson  staff  -        10 Nov 17 17:02 hi.txt

/Volumes/MyAPFS:
total 8
drwxrwxrwx  7 davidanderson  staff  - 224 Nov 17 17:17 .fseventsd
-rwxrwxrwx  1 davidanderson  staff  -  10 Nov 17 17:02 hi.txt

/Volumes/MyExFAT:
total 128
drwxrwxrwx  1 davidanderson  staff  hidden 32768 Nov 17 19:37 .fseventsd
-rwxrwxrwx  1 davidanderson  staff  -         10 Nov 17 17:02 hi.txt

/Volumes/MyJHFS+:
total 8
drwxrwxrwx  7 davidanderson  staff  - 238 Nov 17 17:17 .fseventsd
-rwxrwxrwx  1 davidanderson  staff  -  10 Nov 17 17:02 hi.txt

Note the following:

• All ._* files have been removed.
• None of the hi.txt files have extended attributes.
• The results are the same as Case 1.

macOS Catalina version 10.15.7 was used to test this answer.