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Variable concatenate

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# 1  
Old 02-25-2011
Variable concatenate
Hello,

It might be stupid question But I will ask it any waySmilie

Code:
var1="1 2 3 4" 
var2="5 6 7 8"

var3=$var1\ $var2
var4="$var1\n$var2"

echo "$var1"
echo "$var2"
echo "$var3"
echo "$var4"

The result of executing this code is as follow
1 2 3 4
5 6 7 8
1 2 3 4 5 6 7 8
1 2 3 4\n5 6 7 8
Why the escape is not working, I want variable 4 to look like this
1 2 3 4
5 6 7 8
I change the code like this
Code:
var1="1 2 3 4" 
var2="5 6 7 8"

var3=$var1\ $var2
var4="$var1
$var2"

echo "$var1"
echo "$var2"
echo "$var3"
echo "$var4"

it worked but it is ugly.
# 2  
Old 02-25-2011
Most likely your echo implementation needs an explicit option, in order to interpolate escape sequences:

Code:
$ echo \\n
\n
$ echo -e \\n

$

# 3  
Old 02-25-2011
Hello,


I do not think it is related to echo. Usually I am using echo without any problem. I think it is related on how I concatenate the variables
Code:
var4="$var1\n$var2"

Last edited by radoulov; 02-25-2011 at 10:53 AM.. Reason: Code tags, please!
# 4  
Old 02-25-2011
It's because you're using an escape sequence in the variable value.
Did you try to use the -e option?

Code:
$ v1=a v2=b v3="$v1\n$v2"
$ echo "$v3"
a\nb
$ echo -e "$v3"
a
b

echo's behavior and options vary between systems,
consider using printf for greater portability.
Last edited by radoulov; 02-25-2011 at 11:14 AM..
# 5  
Old 02-25-2011
Alternatively consider using the POSIX version of the echo utility. See echo
# 6  
Old 02-25-2011
Hello,

Thanks for the reply, and you are right. However this behavior cause a problem for me in another scenarios. it is not just only echo.
For example

Code:
var1="1 2 
1 2" 
var2="5 6 
7 8
7 8"
var3="$var1\n$var2"
var4=$(echo "$var3" | sort | uniq)
echo "$var4"

and now the result is
1 2
1 2\n5 6
7 8

and I want it to be

1 2
5 6
7 8

I can solve it as how I did in my first post but this is ugly, because I have the variables in different rows.
# 7  
Old 02-25-2011
And why are you using a separate variables in the first place?
I would handle such a situation using an array, not scalar variables.
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