eval in shell scripting - Page 2

era · #1 (**permalink**) 05-22-2008

You should probably start a new thread for an unrelated question anyway.

wumpus · #2 (**permalink**) 06-25-2009

/bin/sh$ var=foo
/bin/sh$ foo=bar
/bin/sh$ eval echo \${$var}
bar
/bin/sh$ val=`eval echo \${$var}`
bad substitution

How can I save the output of eval echo \${$var} to a variable?

Thanks.

rubin · #3 (**permalink**) 06-25-2009

Quote:

Originally Posted by wumpus

/bin/sh$ var=foo
/bin/sh$ foo=bar
/bin/sh$ eval echo \${$var}
bar
/bin/sh$ val=`eval echo \${$var}`
bad substitution

How can I save the output of eval echo \${$var} to a variable?

Thanks.

Maybe something like this:

Code:

$ var=foo

$ foo=bar

$ set -x

$ cmd='eval echo \${$var}'
+ cmd='eval echo \${$var}'

$ val=$(eval $cmd)
++ eval eval echo '\${$var}'
+++ eval echo '${foo}'
++++ echo bar
+ val=bar

$ echo $val
+ echo bar
bar

wumpus · #4 (**permalink**) 06-25-2009

Quote:

Originally Posted by rubin

Maybe something like this:

Code:

$ var=foo

$ foo=bar

$ set -x

$ cmd='eval echo \${$var}'
+ cmd='eval echo \${$var}'

$ val=$(eval $cmd)
++ eval eval echo '\${$var}'
+++ eval echo '${foo}'
++++ echo bar
+ val=bar

$ echo $val
+ echo bar
bar

That works for Korn shell, but I was looking for a Bourne shell solution.

---------- Post updated at 01:24 PM ---------- Previous update was at 01:11 PM ----------

/bin/sh$ var=foo
/bin/sh$ foo=bar
/bin/sh$ val=`eval echo \\$\${var}`
/bin/sh$ echo ${val}
bar

Thank you Ken!

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