[siebenmann]

In this case, one reason to use printenv is that it is an external command, and so it is clearly and unambiguously seeing (and reporting) whatever the Bourne shell would export into the environment for a real command. In this specific case, it appears that set does not report such single-command variables (whether or not they have a value, eg 'FRED=barney set | grep FRED').

(I am the author of the linked-to entry.)

[1vuio0pswjnm7]

Missing semicolon.

   FRED=barney; set | grep FRED

Also there is no need for grep, nevermind grep -F (fgrep), if using printenv.

   FRED=barney printenv FRED

Without semicolon

   sh -c 'FRED=barney set|grep FRED'

   echo 'FRED=barney set|grep ^FRED'|sh

[_TwoFinger]

> Missing semicolon.

It's not missing. PP is making a point about "single-command variables."

[dcassett]

>Missing semicolon.

If you add a semicolon then FRED is no longer a single command variable (it persists)

> on NetBSD, one can do this

Linux also does the expected thing:

$ FRED=barney printenv FRED

barney