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Bash IFS

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# 15  
Old 09-06-2012
However I would keep the one described below, yes?

Code:
IFS="|="         
set -- $*
unset IFS

---------- Post updated at 06:51 PM ---------- Previous update was at 06:43 PM ----------

Quote:
Originally Posted by Corona688
You shouldn't be unsetting IFS, that could cause weird things later.

I'd reccomend doing things the way I showed you, instead.
I always thought that if I set a different IFS, I would need to unset it, so it keeps its shell default. Is that not so?

---------- Post updated at 06:56 PM ---------- Previous update was at 06:51 PM ----------

Quote:
Originally Posted by Corona688
Using arrays in shell often makes a problem harder. It looks like you've been struggling, but it's simple enough the traditional way... Just read into the variables you want and prefix it with IFS to let it split on what you want. Three things in one shot and no arrays. And it'll work in any shell, not just BASH.

Code:
# If variable is blank, set it
[ -z "$val_xSrc" ] && val_xSrc="-1.0/0/1.0"

# Prefixing a variable to a command sets that variable for only that line
IFS="/" read xSrc1 xSrc2 dxSrc <<EOF
${val_xSrc}
EOF

echo "xSrc1 = $xSrc1"
echo "xSrc2 = $xSrc2"
echo "dxSrc = $dxSrc"

I can't quite understand what you mean by your second comment

Code:
# Prefixing a variable to a command sets that variable for only that line

Do you mean that the change in IFS is only temporary when filling

Code:
xSrc1 xSrc2 dxSrc

but continues to be the bash default for the rest of the script?
# 16  
Old 09-06-2012
Quote:
Originally Posted by kristinu
However I would keep the one described below, yes?

Code:
IFS="|="         
set -- $*
unset IFS

What about the original code you had, where you did OLDIFS="$IFS" to put it back later? You want IFS to be default. You don't want it to actually be blank.
Quote:
I always thought that if I set a different IFS, I would need to unset it, so it keeps its shell default. Is that not so?
You want IFS to be default. You don't want it to actually be blank.
Quote:
I can't quite understand what you mean by your second comment

Code:
# Prefixing a variable to a command sets that variable for only that line

Do you mean that the change in IFS is only temporary when filling

Code:
xSrc1 xSrc2 dxSrc

but continues to be the bash default for the rest of the script?
Yes. Putting X=Y before a command sets that variable only for that line, and leaves it unchanged in the rest. It doesn't work everywhere, but it works for any external commands and also for the read builtin.
# 17  
Old 09-06-2012
I thought reset IFS puts the default and not blank.
# 18  
Old 09-06-2012
It does not.
# 19  
Old 09-06-2012
This might work better.

Code:
IFS="/" read xSrc1 xSrc2 dxSrc <<< "${val_xSrc}"

Last edited by kristinu; 09-06-2012 at 09:52 PM..
# 20  
Old 09-06-2012
Quote:
Originally Posted by kristinu
I thought reset IFS puts the default and not blank.
If IFS is unset, or its value is exactly <space><tab><newline>, the default, then sequences of <space>, <tab>, and <newline> at the beginning and end of the results of the previous expansions are ignored, and any sequence of IFS characters not at the beginning or end serves to delimit words.

Code:
mute@flo-rida:~$ echo $'[ space\t tab\nnewline]' | { IFS=/ read -rd '' lb s t n rb; echo "$lb:$s:$t:$n:$rb"; }
[ space  tab
newline]
::::
mute@flo-rida:~$ echo $'[ space\t tab\nnewline]' | {  read -rd '' lb s t n rb; echo "$lb:$s:$t:$n:$rb"; }
[:space:tab:newline]:
mute@flo-rida:~$ unset IFS
mute@flo-rida:~$ echo $'[ space\t tab\nnewline]' | {  read -rd '' lb s t n rb; echo "$lb:$s:$t:$n:$rb"; }
[:space:tab:newline]:

# 21  
Old 09-06-2012
Is Corona correct?
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