Enrico
If you have sql*navigator or Toad it would make it easier to copy paste the output, if you just use sql*plus then you need to spool to file and run the file as a script:
Thus login into your schema as the owner
SQL>spool yourfile.sql
SQL>set pages 0
SQL>set feedback off
SQL>set echo off
SQL>select 'truncate table '||table_name||' resuse ;' from user_tables ;
SQL> spool off
You want to quickly edit yourfile.sql and
take the command that is repeated out and then save.
SQL> get yourfiles.sql
SQL> r
Look before you leap