IFS=

[tempest92]

hi guys,

i want to read through a file line by line identifying records that match a pattern. i have found some code that does what i want -

grep TEXT /my/file |
while IFS= read -r LINE
do
echo $LINE
done

can someone just tell me what the 'IFS=' is actually doing ?

thanks !!

 

[Ogzilal]

Hi,

IFS stands for Internal Field Separator.
In your case, IFS= means that no Internal Field Separator is defined, so command 'read' will read th whole line.

echo " a b,c d e f g" |
while IFS= read -r L1 L2 L3
do
echo L1=$L1
echo L2=$L2
echo L3=$L3
done

The same sample with IFS set to space will produce another output

echo " a b,c d e f g" |
while IFS=" " read -r L1 L2 L3
do
echo L1=$L1
echo L2=$L2
echo L3=$L3
done

 

[Ogzilal]

Hi,

I forget to tell that IFS is a standard shell variable.

 

[tempest92]

thanks aau for the prompt response !! have a good day !