eval

Evaluate and execute arguments

$ eval "[echo \$HOME]"

$ cmd="ls -la"; eval "$cmd"

$ var="PATH"; eval "echo \$$var"

$ action="date"; eval "$action"

eval [argument...]

eval is a shell builtin that concatenates its arguments, performs shell expansions, and executes the result as a command. It enables dynamic command construction and double expansion of variables.
The command is useful when command strings are built programmatically or stored in variables. It allows variable indirection (accessing a variable whose name is in another variable).
eval's two-pass evaluation makes it powerful but also potentially dangerous with untrusted input.

ARGUMENT

Arguments to concatenate and execute.

Security risk with untrusted input. Can execute arbitrary commands. Debugging eval'd commands is difficult. Quoting must be handled carefully.

eval is a standard POSIX shell builtin, present in Bourne shell and all its derivatives. It provides essential metaprogramming capabilities for shell scripts.

bash(1), sh(1), exec(1)