whats is the meaning of using exec and then read in ksh script

问题

THe script is like exec 8< $SEQ_FILE read -u8 DATE SEQ_NUMBER Can you please help me in understanding what this means?

回答1:

The exec 8< $SEQ_FILE opens the file $SEQ_FILE for reading and associates it with file descriptor 8. All further commands can then read from that file descriptor.

The command read -u8 DATE SEQ_NUMBER then does exactly that. It reads one line from that file and puts the line into two variables (split according to shell rules, typically at a space).

来源：https://stackoverflow.com/questions/21753477/whats-is-the-meaning-of-using-exec-and-then-read-in-ksh-script