How to clear the log file and write it again?

Question

I create the log file by this way:

    global logger
    logger = logging.getLogger("plus_dig_cname")
    logger.setLevel(logging.DEBUG)

    fh = logging.FileHandler( fdoc_log + "/plus_dig_cname.log" )

    formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
    fh.setFormatter(formatter)

    logger.addHandler(fh)

and when the size of plus_dig_cname.log is bigger than 300MB,I handle it by a shell script, the main process is:

 mv $LOG_DIR/$1 $LOG_DIR/$1.bk
 [ $? -ne 0 ] && return 1
 touch $LOG_DIR/$1
 [ $? -ne 0 ] && return 1
 chmod 666 $LOG_DIR/$1
 [ $? -ne 0 ] && return 1

just mv it and touch a new one.
The problem is the logger can't wirte anything in the file of plus_dig_cname.log. The logging can't work.
Maybe it can be solved it by:

with open( "plus_dig_cname.log", "w" ):
               pass

this way can get a new log file by Python. But i want to get the new log file by Bash.

So, why the logging can't work after "mv touch chmod"?

Thank you

Answer 1

Use a RotatingFileHandler to have this handled for you.

For example:

MAX_SIZE = 300 * 1024 * 1024
LOG_PATH = fdoc_log + "/plus_dig_cname.log"
fh = logging.handlers.RotatingFileHandler(LOG_PATH, maxBytes=MAX_SIZE, backupCount=5)

This will create 5 backups of 300MB each.