spawn is a shell script designed to start the execution of the specified simple command with the given arguments. The command is run in the background; specifically, spawn executes command in a sub-shell (Bourne shell). This sub-shell will be niced to level level if the -n option is specified. The stdout and stderror of the sub-shell is redirected to log_file, or, if the -l option is not given, to a file named "log". If the option -t is specified, then spawn uses /usr/bin/time to time the execution of the sub-shell.
log_file (or "log" if -l is not given) is stamped with the name of the host and the date and time of the start of the execution of the sub-shell. The stdout and stderr of the sub-shell are then redirected to log_file. Finally, after the sub-shell exits, the date and time of the sub-shell termination are recorded to log_file.