macos – Why does lsof -F pc print file descriptors even when not specified?


I’m using the lsof command to list processes using port 53 on macOS. I want to display only the process ID (p) and command name (c) fields, but the output also includes file descriptors (f), even though I only requested -F pc.

Here is the command I’m running:

sudo lsof -nP -i:53 -F pc +c0

However, the output includes file descriptors:

p21409
cmDNSResponder
f17
f18
f19
f20
f47
p22154
cnc
f3

I only want to see the process ID and command name, but the file descriptors are still being printed.

lsof version:

 % lsof -v       
lsof version information:
    revision: 4.91
    latest revision: ftp://lsof.itap.purdue.edu/pub/tools/unix/lsof/
    latest FAQ: ftp://lsof.itap.purdue.edu/pub/tools/unix/lsof/FAQ
    latest man page: ftp://lsof.itap.purdue.edu/pub/tools/unix/lsof/lsof_man
    configuration info: libproc-based
    Anyone can list all files.
    /dev warnings are disabled.
    Kernel ID check is disabled.

Question:
Why does lsof print file descriptors (f) when I explicitly specify the -F pc options? Is this the expected behavior? How can I ensure that only the process ID and command name are printed, without the file descriptors?


Edit:
When I run the command without -F pc, this is the output I get:

sudo lsof -nP -i:53 +c0
COMMAND         PID           USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
mDNSResponder 21409 _mdnsresponder   17u  IPv4 0x111969c556757e3f      0t0  UDP *:53
mDNSResponder 21409 _mdnsresponder   18u  IPv6 0x5524ed7878be51b4      0t0  UDP *:53
mDNSResponder 21409 _mdnsresponder   19u  IPv4 0xae0066809727a98c      0t0  TCP *:53 (LISTEN)
mDNSResponder 21409 _mdnsresponder   20u  IPv6 0xe4f19df38f2c4a9e      0t0  TCP *:53 (LISTEN)
mDNSResponder 21409 _mdnsresponder   47u  IPv4 0x6981d98eaa5f9130      0t0  TCP 100.114.184.213:53->100.114.184.213:60587 (ESTABLISHED)
nc            22154     mohitkumar    3u  IPv4 0x634de6cd4ff0d2d7      0t0  TCP 100.114.184.213:60587->100.114.184.213:53 (ESTABLISHED)


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