Lookup variable value from string in shell script

Question

In bash, if I have:

y=10
x='y'
echo $x # prints 'y'

Now I want to get $y via $x:

echo ${$x} # error: "bad substitution"; I want to print 10

How do I lookup the variable value with name $x?

@m0skit0 please, no eval -- it has substantial security implications, as documented at mywiki.wooledge.org/BashFAQ/048. The right way, indirect variables, is documented at mywiki.wooledge.org/BashFAQ/006 — Charles Duffy
– Charles Duffy, Commented Jun 6, 2012 at 17:35
Everything has good and bad uses. You just have to know how to use it. — m0skit0
– m0skit0, Commented Jun 6, 2012 at 21:51

choroba · Accepted Answer · 2012-06-06 17:33:02Z

7

See Parameter Expansion in bash manual:

echo ${!x}

answered Jun 6, 2012 at 17:33

choroba

245k27 gold badges221 silver badges304 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

k107 · Accepted Answer · 2012-06-06 17:41:27Z

0

Use eval for indirect references while escaping the outer dollar sign

eval echo "\${$x}"

To assign to a variable

eval "z=\${$x}"
echo "$z"
# 10

answered Jun 6, 2012 at 17:41

k107

16.7k13 gold badges65 silver badges61 bronze badges