Free bonus hint: start sbcl through rlwrap, then you get the libreadline facilities (arrow up for last command etc.)
First, navigate to the downloaded directory, let's say it is in ~/snmp1.
rlwrap sbcl
or just
sbcl
Then in the REPL, type
(require 'asdf)
(asdf:operate 'asdf:load-op :snmp1)
The idea is that the current directory is in *default-pathname-defaults*, which is included in ASDF:*CENTRAL-REGISTRY*, therefore asdf will automatically find the system description file snmp1.asd
In emacs, first find (read) a .lisp-file in the directory where you downloaded snmp1. For exampel ber.lisp
Then start slime in emacs using M-x slime
Then in the slime-repl buffer, type
(asdf:operate 'asdf:load-op :snmp1)
The idea is that the directory of the lisp-file you just read into emacs is in *default-pathname-defaults*, and therefore also in ASDF:*CENTRAL-REGISTRY*, therefore asdf will automatically find the system description file snmp1.asd
Find a suitable location to download snmp1. I suggest somewhere in your home directory rather than in a root-owned directory, as asdf will sometimes have to write compiled files when it builds the system. (updates, change of sbcl version). The directory .sbcl/site might be ok.
Create a link from a directory that is already in ASDF:*CENTRAL-REGISTRY* to the snmp1.asd file. Just evaluate ASDF:*CENTRAL-REGISTRY* in the REPL to find out, ~/.sbcl/systems should be in there. So
cd ~/.sbcl/systems
ln -s ~/.sbcl/site/snmp1/snmp1.asd .
You will now be able to load the system, using asdf as above, from anywhere.
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