Re: [Bashburn-info] I think I fixed the AUTHOR problem.

[Steven W. O. <st...@sy...>]

On Sunday, Sep 21st 2008 at 16:34 -0000, quoth Anders Lind?n:

=>Meh, I sent my reply to Steven and not the list. Reposting it here.
=>
=>If I'm not mistaken, IFS is something that is treated as a space or
=>newline character no? You can set a character like @, : or | in our case
=>to be treated as a whitespace to separate text fields?
=>
=>On Sun, 2008-09-21 at 16:17 -0400, Steven W. Orr wrote:
=>> It looks like we have three different values that are being used for IFS. 
=>> There's the IFS=: which is needed to read a bbrc file. There's IFS=@ used 
=>> to pass uneval'd data to bbconfmenu. And now there's IFS='|' which is 
=>> needed to store configure_changes. (BTW, the implication is that a config 
=>> val may no longer contain an embedded pipe char.)
=>> 
=>> Nick, I hope this works. There's always one guy who screws up and makes 
=>> people aware that he's good at testing. I consider it a blessing. ;-) The 
=>> good news is that if you find anything wrong with it, it should be easy to 
=>> fix. (I try to never let people know that I know how to get the printer
=>> working. ;-)
=>> 
=>> On a related topic, I was just curious. Do people understand what IFS is 
=>> and what I'm doing with it? How it gets restored? etc...?

Close. IFS is used as the mechanism to tell bash how to parse text. For 
example, if I have

foo='This is a string: It has some stuff in it. And it's 2:00PM.'
then I can say
set -- $foo
After the set command, 
$1 will be 'This'
$2 will be 'is'
$3 will be 'a'
and $4 will be 'string:'

But if I was to say
IFS=:
set -- $foo
then $1 will be 'This is a string'
$2 will be ' It has some stuff in it. And it's 2'
and $3 will be '00PM.'

In addition, lists will be taken apart differently (for example is for 
loops, depending on IFS. All the values of IFS that I work with are local 
copies in subroutines. e.g.,

subX()
{
    typeset old_IFS="$IFS"
    typeset IFS="$old_IFS"

The default value for IFS is whitespace

533 > echo "$IFS" | od -bc
0000000 040 011 012 012
             \t  \n  \n
0000004


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