"#" is the special character to allow running of SQLPlus commands, eg
SQL> select *
2 #desc scott.emp
Name Null? Type
----------------------------------------------------- -------- ----------------------
EMPNO NOT NULL NUMBER(4)
ENAME VARCHAR2(10)
JOB VARCHAR2(9)
MGR NUMBER(4)
HIREDATE DATE
SAL NUMBER(7,2)
COMM NUMBER(7,2)
DEPTNO NUMBER(2)
2 from scott.dept;
DEPTNO DNAME LOC
---------- -------------- -------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
4 rows selected.
Control it with "sqlprefix"
SQL> set sqlprefix ~
SQL> select *
2 ~desc scott.emp
Name Null? Type
----------------------------------------------------- -------- -----------------
EMPNO NOT NULL NUMBER(4)
ENAME VARCHAR2(10)
JOB VARCHAR2(9)
MGR NUMBER(4)
HIREDATE DATE
SAL NUMBER(7,2)
COMM NUMBER(7,2)
DEPTNO NUMBER(2)