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Operating Systems Linux Use read to set a variable.
# 1  
Old 03-20-2012
Use read to set a variable.
Hi all,
I used to set variable by read from keyboard
Code:
read -p 'Input new value for variable :' var

Now I want to pipe from ls and set to var
a.txt b.txt c.txt
Code:
ls | grep a.txt | read var

why this cannot set the $var.
What is the different between them....Smilie
# 2  
Old 03-20-2012
grep requires a pattern as an argument

eg.
Code:
grep foo a.txt

# 3  
Old 03-20-2012
what pattern i need?
ls | grep a.txt will ouput
Code:
a.txt

which I want to set to variable. I think this will similar to input from keyboard...
# 4  
Old 03-20-2012
oh - I see what your trying to do now. when reading from a pipe you should use a while loop

Code:
ls | grep a.txt | while read var
do
   echo $var
done

# 5  
Old 03-20-2012
thx frank_rizzo,
It works,
But why it can't set the var out of the loop scope?
Code:
var='b.txt'
echo $var

then I execute the loop
Code:
ls | grep a.txt | while read var
do
   echo $var
done
echo $var

the variable still be b.txt, not a.txt. the pipe should work like stdio from keyboard?
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