[ILUGC] Re: help to understand this bash output
- From: Raman Pandarinathan <raamanp@xxxxxxxxx>
- To: ilugc@xxxxxxxxxxxxx
- Date: Mon, 16 Jan 2023 12:05:09 +0530
On Sun, Jan 15, 2023 at 12:33 AM M K Saravanan <mksarav@xxxxxxxxx> wrote:
Hi,
Can someone help me to understand this bash output:
$ echo '1 2 3 4 5 6' | while read a b c; do
echo result: $c $b $a;
done
result: 3 4 5 6 2 1
What logic is used to arrive at that answer?
1. read reads entire echo in one go.
2.No use of while in this case
3.When read reads a b c here is the assignment
a=1 b=2 and c='3 4 5 6'
Hence when you echo $c $b $a
You get (3 4 5 6) (2 ) (1)
You can understand shell execution better by using -x option.
Here is the output of the script saved and run with -x option
sh -x scriptfile
+ echo 1 2 3 4 5 6
+ read a b c
+ echo 1
1
+ echo 2
2
+ echo 3 4 5 6
3 4 5 6
+ read a b c
Raman.P
blog:
http://ramanchennai.wordpress.com/
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