Using exec and tee to redirect logs to stdout and a log file in the same time

Use process substitution with & redirection and exec:

exec &> >(tee -a "$log_file")
echo "This will be logged to the file and to the screen"

$log_file will contain the output of the script and any subprocesses, and the output will also be printed to the screen.

• >(...) starts the process ... and returns a file representing its standard input.

• exec &> ... redirects both standard output and standard error into ... for the remainder of the script (use just exec > ... for stdout only).

• tee -a appends its standard input to the file, and also prints it to the screen.

exec >> $log_file 2>&1 && tail $log_file