logging.liddle

#!/bin/bash

PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/root/scripts/working/Liddle

function startLog {

#           --------------------------------------------------
#                       Function to begin Logging
#  Can recieve one argument to indicate that the log should be appended
#           --------------------------------------------------

#   Ensure that the named pipe does not already exist before creating it
    if [ ! -e ${core[PIPE]} ]; then
        mkfifo ${core[PIPE]}
    fi

    # Redirect output of file descriptors 3 and 4 to screen
    # (default location of file descriptors 1 and 2)
    exec 3>&1 4>&2
    
    # Check to see if the function has had continue passed to it
    # If it has then append the log rather than overriding
    # Tee takes from stdin and writes to file $LOG
    # Tee's stdin will redirect from the $PIPE (Redirection is the capturing of something)
    # Redirect tees stdout to 3 which is the stdout of the script
    # & makes this a background process
    if [ "${1}" == "continue" ]; then
        tee -a ${core[LOG]} < ${core[PIPE]} >&3 &
    else
        tee ${core[LOG]} < ${core[PIPE]} >&3 &
    fi

    # Save the process id of tee so it can be closed later
    core[TPID]="${!}"

    # Redirects the stdout (1) of the script to the $PIPE
    # Also redirects stderr(2) to stdout(1) so they are both redirected
    exec > ${core[PIPE]} 2>&1
    # Indicate script has began logging
    core[LOGGING]="true"

}

function endLog {

#           --------------------------------------------------
#                        Function to end Logging
#                      Ignores any arguments given
#           --------------------------------------------------

    # Restore stdout and stderr to their defaults and close 3 and 4
    exec 1>&3 3>&- 2>&4 4>&-
    # Wait until tee has closed, it will close because the named pipe has
    # no more input connection (previously had through file descriptor 3)
    wait "${core[TPID]}"
    # Finally remove the pipe
    rm ${core[PIPE]}
    # Script no longer logging
    core[LOGGING]="false"
}