sqlplus show all tables command

That is not exactly  how to do it...

You need to log into sqlplus before you start  the script.

however,  you do not need to use grep --  you can specify the table_name in the where clause to limit the output,  I will show an example below....

Here is a way to do it from a DBA account....
------all tables using the DBA_Tables VIEW ------------
$ sqlplus system
SQL*Plus: Release 8.1.6.0.0 - Production on Fri Dec 29 13:32:29 2000
(c) Copyright 1999 Oracle Corporation.  All rights reserved.
Enter password:
Connected to:
Oracle8i Enterprise Edition Release 8.1.6.0.0 - Production
With the Partitioning option
JServer Release 8.1.6.0.0 - Production

SQL> select owner, table_name, tablespace_name
  2  from dba_tables
  3  group by owner,table_name, tablespace_name
  4 /

OWNER          TABLE_NAME                     TABLESPACE_NAME
-------------- ------------------------------ ---------------
OUTLN          OL$                            SYSTEM
OUTLN          OL$HINTS                       SYSTEM
SCOTT          CUSTAB                         DATA
SCOTT          CUSTOMER3                      DATA
SCOTT          CUSTOMERTABLE                  DATA
SCOTT          DATA                           DATA
SCOTT          DISTINCTDEMO                   DATA
SCOTT          HOUSING                        DATA
SCOTT          INNER                          DATA
SCOTT          OUTER                          DATA
SCOTT          PLAN_TABLE                     DATA

OWNER          TABLE_NAME                     TABLESPACE_NAME
-------------- ------------------------------ ---------------
SCOTT          STUDENT                        DATA
SCOTT          TEST                           DATA
SCOTT          TESTING                        DATA
SCOTT          TEXTLOAD                       DATA
SCOTT          UPDATETEST                     DATA
SCOTT          WASHERS                        DATA
…….  (I cut the out put short ---  too many lines to post)

Another way would be to query the tables owned by the user that you are logged in as,
for example,  using the scott user:
------- All user tables using the USER_TABLES view-------
SQL> connect scott
Enter password:
Connected.
SQL> l
  1  select table_name, tablespace_name
  2  from user_tables
  3* group by table_name, tablespace_name
SQL> /

TABLE_NAME                     TABLESPACE_NAME
------------------------------ ---------------
CUSTAB                         DATA
CUSTOMER3                      DATA
CUSTOMERTABLE                  DATA
DATA                           DATA
DISTINCTDEMO                   DATA
HOUSING                        DATA
INNER                          DATA
OUTER                          DATA
PLAN_TABLE                     DATA
STUDENT                        DATA
TEST                           DATA
TESTING                        DATA
TEXTLOAD                       DATA
UPDATETEST                     DATA
WASHERS                        DATA

15 rows selected.


--------------------------------------------------
Another  way to check the table's existance  is from the object's owner account  ( for example puposes,  we will be using the scott user again),   using the sqlplus DESCRIBE command


SQL> describe STUDENT
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 SID                                       NOT NULL CHAR(4)
 FNAME                                     NOT NULL VARCHAR2(10)
 LNAME                                     NOT NULL VARCHAR2(10)
 MAJOR                                     NOT NULL VARCHAR2(10)
 DORM                                      NOT NULL VARCHAR2(7)

------ Example of narrowing the output using the where clause to search for your object ---------
$ sqlplus scott/tiger
SQL*Plus: Release 8.1.6.0.0 - Production on Fri Dec 29 13:48:25 2000
(c) Copyright 1999 Oracle Corporation.  All rights reserved.
Connected to:
Oracle8i Enterprise Edition Release 8.1.6.0.0 - Production
With the Partitioning option
JServer Release 8.1.6.0.0 - Production

SQL> select table_name, tablespace_name
  2  from user_tables
  3  where table_name = 'STUDENT'
  4  /

TABLE_NAME                     TABLESPACE_NAME
------------------------------ ------------------------------
STUDENT                        DATA


======================================

To it from the system prompt,     put the sql in a file, and then execute it,  example:

$ cat tables.sql
select table_name, tablespace_name
from user_tables
group by table_name, tablespace_name
/
exit
$ sqlplus scott/tiger @tables.sql |grep STUDENT
STUDENT                        DATA
$
======================

Hope this answers your question....
sincerely,
dBalaski