RE: Korn Shell and arithemetic

From: Bobak, Mark <Mark.Bobak_at_il.proquest.com>
Date: Wed, 23 Jun 2004 14:24:29 -0400
Message-ID: <4C9B6FDA0B06FE4DAF5918BBF0AD82CFECFD1E@bosmail00.bos.il.pqe>

Ryan,

He's using a in-line rediriection to supply input to bc, an external = program.

bc << __EOF__
means read everything from stdin as input to the 'bc' program, until you = encounter __EOF__.
^J is a linefeed,

1.2 > 1.0 is the expression to be evaluated by 'bc',
^J, another line feed,=20

__EOF__ is the end of input to 'bc'.
Now that entire thing is enclosed in backquotes (`). That means that = the output of the program, which would normally go to stdout, is return = to the shell as a literal. That literal is enclosed in double quotes = ("), and
=3D "1" is compared to "1".

So, bc returns 1 if the expression is true and 0 if the expression is = false.

Note, however, that it appears the GNU version of bc is required, the = standard bc on Solaris 8 does this:
SQL> !bc
1.2 > 1.0
syntax error on line 1, teletype

Hope that helps,

-Mark

-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of ryan.gaffuri_at_comcast.net
Sent: Wednesday, June 23, 2004 1:57 PM
To: oracle-l_at_freelists.org
Subject: OT: Korn Shell and arithemetic

Tim,=20

what does this syntax mean?=20

$ if [[ "`bc << __EOF__^J1.2 > 1.0^J__EOF__`" =3D "1" ]]

    > then
    > echo yes
    > else echo no
    > fi

yes

$ if [[ "`bc << __EOF__^J1.2 > 1.3^J__EOF__`" =3D "1" ]]

    > then
    > echo yes
    > else echo no
    > fi
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Received on Wed Jun 23 2004 - 13:21:26 CDT