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KSH scripting question

Posted on 2013-06-12
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Last Modified: 2013-06-12
I am looking over the ksh script and there is a line

sqlplus "/ as sysdba" <<!


I was wondering what is <<! part of it? What does it do?

I know that >> appends output to a file and that < is a standard input, but what about << in a conjunction with !
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Question by:YZlat
7 Comments
 
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farzanj earned 250 total points
ID: 39241157
Just processes output until it sees ! in a line.

So it will process all lines below this command until it sees !

command << END_TAG
abc
def
adf
END_TAG

Your end tag is !
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by:YZlat
ID: 39241215
I see. But there isn't any ! anywhere in my script
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Expert Comment

by:nemws1
ID: 39241241
farzanj is 100% correct.  Just tested this on my box with ksh:

$cat <<!
> what
> is 
> up
> man
> !
what
is
up
man
$

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Expert Comment

by:DOSLover
ID: 39241248
This says the input begins after the next new line and continues until there is a line containing only the delimiter. In your case the delimiter is !

Here is a link that might help: http://pic.dhe.ibm.com/infocenter/aix/v7r1/index.jsp?topic=%2Fcom.ibm.aix.baseadmn%2Fdoc%2Fbaseadmndita%2Fkorn_shell_inout_redir.htm
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Expert Comment

by:ozo
ID: 39241257
if there is no terminating ! then ksh may just read to the end of the script
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Expert Comment

by:nemws1
ID: 39241307
ozo is correct.  bash prints out an error, ksh does not and happily accepts an end-of-file terminator:

$cat <<!
> hey
> there
> man
^Dhey
there
man
$
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Author Closing Comment

by:YZlat
ID: 39241327
Thanks, got it!
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