You could use wtime:
wtime [ -t task ] [ ]
-t task
Specify the name of the task. It has to be a valid file-
name. Only the first 32 characters are taken into account.
The default value is "default".
action is one of the following:
-h Display help.
-a Start counting.
-s Stop counting.
-c Display current elapsed time in seconds.
-r [ start [ end ]]
Display time spent on the task during the specified
period. The parametres start and end represent the
begginning and end of the reporting period respec-
tively. The format of start and end is '%d-%m-%Y'
(see strptime (1)). The default values are the cur-
rent time for end and the begginning of the current
month for the start parameter.
