How to put special characters in variable and use them in string?

Question

I'm wondering is there anyway to use for example , or ^ or % and so on, from variables in Bash ?

in instance I have three variables

var1='hello world'
var2=${var1:3}
var3='^'

I want to do this in bash ! please attention to my question I know it's very simple in other ways but how about this ?

echo ${var1:0:3}${var2$var3} # instead of echo ${var1:0:3}${var2^}

and finally output is :

heLlo world

Case modification expansion is done before variable expansion. — anubhava
– anubhava, Commented Dec 9, 2019 at 11:34
What is the problem that you are trying to solve ? You can use eval, but this may bring security problem. — dash-o
– dash-o, Commented Dec 9, 2019 at 12:52

dash-o · Accepted Answer · 2019-12-09 13:03:09Z

1

In theory, eval can do execute arbitrary code, but has many security issues, so it should be used as last resort. Use it only when you trust the input 100%.

var1='hello world'
var2=${var1:3}
var3='^'

eval echo '${var1:0:3}${var2'$var3'}'

answered Dec 9, 2019 at 13:03

dash-o

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1 Comment

Freeman Over a year ago

thnx yes eval is evil 😉 and it's dangerous, repp ++ I'm waiting for other possible ways ...

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