How to tell where the file read offset by a process

source: https://unix.stackexchange.com/questions/34751/how-to-find-out-the-file-offset-of-an-opened-file

1. $ cat /proc/687705/fdinfo/36

pos:    26088
flags:  0100001

in case of symbolic links:

readlink /proc/$PID/fd/$N

2.

>lsof -o file1.st1
COMMAND   PID  USER   FD   TYPE DEVICE     OFFSET    NODE   NAME
process  24017 user1 18r   REG  253,3    0x14a85000 6330199 file1.st1