在POSIX shell中，如何打印变量值的值

Question

In a POSIX shell:

>VALUE=value
>FOOBAR=VALUE

Now how to print the value of $FOOBAR ? $$FOOBAR does not work - it goes left-to-right so interprets $$ first as process ID.

The duplicate question before me that people are pointing to, yes it does contain the answer to my question but it buried in a ton of irrelevant gunk. My question is much simpler and to the point.

Answer 1

For POSIX portability, you are pretty much left with

eval echo \$$variable

The usual caveats apply; don't use eval if the string you pass in is not completely and exclusively under your own control.

I lowercased your example; you should not be using upper case for your private variables, as uppercase names are reserved for system use.

Answer 2

The only way to do this in POSIX is to use eval , so be very certain that FOOBAR contains nothing more than a valid variable name.

$ VALUE=value
$ FOOBAR=VALUE
$ valid_var='[[:alpha:]_][[:alnum:]_]*$'
$ expr "$FOOBAR" : "$valid_var" > /dev/null && eval "echo \$$FOOBAR"