Looks like you're using the bash(1) shell. The command for that shell isThanks, but I've no idea as to carry out the - setenv CFLAGS "-DVIMAGE -DDEV_RANDOM"
export CFLAGS="-DVIMAGE -DDEV_RANDOM".
There are many shells available in Freebsd and other Unix work-alikes. The main families are Bourne, C, and Korn shells. It so happens that Freebsd comes with the C shell as the default for the root user, but Bourne-like shells are pretty dominant nowadays. Bash stands for the "Bourne-Again Shell", BTW.
I consult this page when I'm not sure how to do something in an unfamiliar shell:
See for example: