On 09:09 02 Dec 2002, Ira Childress <[EMAIL PROTECTED]> wrote:
| I'm sure some one has seen this before and hopefully there's a work-around.
|
| houston:/admin/IrasDir # cat wtest
| #!/bin/bash
| #
| myVar="Old Value"
|
| echo "1: "$myVar
|
| echo "New Value" | while read data ; do
| myVar=$data
| echo "2: "$myVar
| done
|
| echo "3: "$myVar
|
| returns,
|
| 1: Old Value
| 2: New Value
| 3: Old Value
|
| In otherwords, myVar gets changed inside the while loop, but doesn't retain
| the value when the loop exits.
Sure. The assignment to myVar is happening in the subshell use for
the loop (because it's a component in the pipeline). There are a few
approaches, which tend to fall into either:
not doing the loop in a subshell
doing the loop in a subshell and manually making what you want
available later
putting the code wanting $myVar also in the subshell
eg:
First method:
echo "New Value" >tempfile
while read data
do myVar=$data
done <tempfile
Which will be run my the main shell because it's not in the pipeline.
Second method:
echo "New value" | while read data
do myVar=$data
echo $myVar >tempfile
done
myVar=`cat tempfile`
Which writes to a tempfile, and the main shell reads from it after the
pipeline finishes.
Third method (which is what I often use):
echo "New Value" | \
{ while read data
do myVar=$data
done
echo $myVar
}
Which puts the post-loop stuff wanting $myVar in the subshell that is
part of the pipeline.
Cheers,
--
Cameron Simpson, DoD#743 [EMAIL PROTECTED] http://www.zip.com.au/~cs/
Ed Campbell's <[EMAIL PROTECTED]> pointers for long trips:
1. lay out the bare minimum of stuff that you need to take with you, then
put at least half of it back.
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