Question

I’m using ksh and having some trouble. Why does this code not run?

[root]$ CMD="ls -ltr"
[root]$ eval "W=$( $CMD )"
[root]$ ksh: ls -ltr:  not found.
[root]$ echo $W 

But this works fine:

[root]$ CMD="ls -ltr"
[root]$ eval 'W=$('$CMD')'
[root]$ echo $W 

Answer 1

You need to escape the $(...) with a backslash to prevent it from being evaluated by the outside shell. The $(...) needs be preserved as is until it is handed off to the eval:

$ CMD="ls -ltr"
$ eval "W=\$( $CMD )"
$ echo $W
total 197092 srwxr-xr-x 1 root root...