shell script problem

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# 1  
Old 08-30-2001
Question shell script problem


I have a shell script problem. I'm using /bin/ksh and I have a script that reads a number of table names from a file adn then for each table name, it creates the table in Oracle8i via sqlplus,

The main sceleton looks something like:

while read tab_name


done < $file

Now, if i just print out $tab_name in the BODY of the while loop, then the while loop behaves as expected.

Howeveer, if I include calls to routines that perform calls to 'sqlplus' and create $tab_name in Orcle8i, the while loop is only executed once. Basically, only the first iteration is performed, and only one $tab_name is read from $file.

Any idea why this is happening?

Any help will be greatly appreciated.


# 2  
Old 08-31-2001

i test a small script and it works fine. Maybe there's something wrong in the "BODY", can you send the complete loop to me ?
# 3  
Old 08-31-2001
If I understand what you are saying, the code you are adding to the loop somewhere includes a program that is reading from standard-in. Since standard-on is set to $file within the loop, it is reading all of your input from $file.

One rememdy would be something like:
sqlplus < /dev/null
which would at least leave the outer loop intact.

But the fact that the program is unexpectedly reading from standard-in indicates that you have others as well.
# 4  
Old 09-01-2001
You'll probably have to do:

sqlplus -s ...

Also, don't terminate the sql script with a '/'
or 'bye' or anything.
# 5  
Old 09-02-2001
Data problem persists


I modified my shell script structure and I no longer call 'sqlplus' from within the while loop (I only build an sql file within the loop now).

However the problem specified in my original e-mail still persists.

The 'BODY' section of the while loop (in summary) executes the following commands:

- /usr/sbin/useradd someuser
- echo "some text" >> /programs/files/somefile
- echo "other text" >> /programs/files/otherfile
- more "somefile" | grep "some seach string"
- su -u "someuser" -c "some command"

Could the above commands somehow interupt the while loop from
normal execution?

Maybe stdin which is originally set to $file (see previous message)
is being overwritten by one of the command in the 'BODY'. I do not explicitly ovewrite stdin anywhere in the 'BODY' of the while loop.

while read tab_name


done < $file

(loop only executes once, even though $file contains
numerous entries)

Any help will be greatly appreciated.

S. Trpeski
# 6  
Old 09-03-2001
Simple suggestion

Have you tried running the script with tracing: set -x and see what happens

Did you check that your input file does not contain blank lines: e.g.: the 2nd line?
# 7  
Old 09-03-2001

Thanks for the help/suggestions everyone ...

I have tried running with the -x debug option and the script terminates at the beggining of the second iteration. Namely,

1. it reads the "while read name" line initially.
2. Executes the loop body.
3. it reads the "while read name" line for the second time.
4. stops because it 'thinks' there is no more data in the $file.

I think this indicates that I have lost my 'stdin' pointer somewhere
in the body of the while loop, but being fairly new with shell scripts, I'm not sure what is happening exactly.

Also, the $file does not contain an empty second line.

Steve T.
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