The first word indicates the number of history events to save. The optional second word (+) indicates the format in which history is printed; if not given, %h\t%T\t%R\n is used. The format sequences are described below under prompt; note the variable meaning of %R. Set to 100 by default.
$ set history= ( 1000 “%h %W/%D/%Y %T %R\n” )
2 09/08/2014 22:48 set history= ( 1000 “%h %W/%D/%Y %T %R\n” )
7 09/08/2014 22:49 ls
9 09/08/2014 22:49 echo “hi”
10 09/08/2014 22:49 history
This would result in the history being maintained for the last 1000 commands with the format of “%h %W/%D/%Y %T %R\n”.
- %h – history #
- %W/%D/%Y – month/day/year
- `%T – 24 hr. time
- %R – command run
The full descriptions of these macros is defined in the tcsh man page, scroll down to the section where the prompt command is explained. They’re there.