I want to enumerate the list of all environment variables available in my Lisp process. I want the same list that is returned by the C variable environ.
Neither SBCL nor Clozure CL seem to provide it out of the box. Can I do it using CFFI?
Interfacing with the OS and common lisp is still quite dependent on your lisp distribution. So more or less is not easy to find a good library that works in all CL distributions.
I recommend you to work with UIOP, which comes with ASDF 3 and above and it is the best library for working with the OS inside common lisp nowadays. However it doesn't have a function to list the environment variables, furthermother if we take a look at how it works with environment varables we can see that for every lisp distribution we have a different version of accessing the variables only for example:
(defun getenv (x)
"Query the environment, as in C getenv.
Beware: may return empty string if a variable is present but empty;
use getenvp to return NIL in such a case."
(declare (ignorable x))
#+(or abcl clasp clisp ecl xcl) (ext:getenv x)
#+allegro (sys:getenv x)
#+clozure (ccl:getenv x)
#+cmucl (unix:unix-getenv x)
#+scl (cdr (assoc x ext:*environment-list* :test #'string=))
#+cormanlisp
(let* ((buffer (ct:malloc 1))
(cname (ct:lisp-string-to-c-string x))
(needed-size (win:getenvironmentvariable cname buffer 0))
(buffer1 (ct:malloc (1+ needed-size))))
(prog1 (if (zerop (win:getenvironmentvariable cname buffer1 needed-size))
nil
(ct:c-string-to-lisp-string buffer1))
(ct:free buffer)
(ct:free buffer1)))
#+gcl (system:getenv x)
#+genera nil
#+lispworks (lispworks:environment-variable x)
#+mcl (ccl:with-cstrs ((name x))
(let ((value (_getenv name)))
(unless (ccl:%null-ptr-p value)
(ccl:%get-cstring value))))
#+mkcl (#.(or (find-symbol* 'getenv :si nil) (find-symbol* 'getenv :mk-ext nil)) x)
#+sbcl (sb-ext:posix-getenv x)
#-(or abcl allegro clasp clisp clozure cmucl cormanlisp ecl gcl genera lispworks mcl mkcl sbcl scl xcl)
(not-implemented-error 'getenv))
(defsetf getenv (x) (val)
"Set an environment variable."
(declare (ignorable x val))
#+allegro `(setf (sys:getenv ,x) ,val)
#+clisp `(system::setenv ,x ,val)
#+clozure `(ccl:setenv ,x ,val)
#+cmucl `(unix:unix-setenv ,x ,val 1)
#+ecl `(ext:setenv ,x ,val)
#+lispworks `(hcl:setenv ,x ,val)
#+mkcl `(mkcl:setenv ,x ,val)
#+sbcl `(progn (require :sb-posix) (symbol-call :sb-posix :setenv ,x ,val 1))
#-(or allegro clisp clozure cmucl ecl lispworks mkcl sbcl)
'(not-implemented-error '(setf getenv))
so for getting one variable:
CL-USER> (uiop:getenv "GEM_PATH")
"/Users/toni/.rvm/gems/ruby-2.1.6@afs-dev:/Users/toni/.rvm/gems/ruby-2.1.6@global"
as pointed in a comment if you are usign SBCL you can get this with it:
SB-EXT:POSIX-ENVIRON
example in c:
extern char **environ;
//...
int i = 0;
while(environ[i]) {
printf("%s\n", environ[i++]); // prints in form of "variable=value"
}
| GEM_HOME=/Users/toni/.rvm/gems/ruby-2.1.6@afs-dev |
| SHELL=/bin/bash |
| TERM=dumb |
| TMPDIR=/var/folders/zs/t9wnzpqj2bdgjjgjwb8pqxc80000gn/T/ |
| Apple_PubSub_Socket_Render=/private/tmp/com.apple.launchd.e0K30SfWTc/Render |
| USER=toni |
| SSH_AUTH_SOCK=/private/tmp/com.apple.launchd.KvlUaU8PD5/Listeners |
| __CF_USER_TEXT_ENCODING=0x1F5:0x0:0x8 |
| PATH=/Users/toni/.rvm/gems/ruby-2.1.6@afs-dev/bin:/Users/toni/.rvm/gems/ruby-2.1.6@global/bin:/Users/toni/.rvm/rubies/ruby-2.1.6/bin/:/usr/texbin:/Library/TeX/texbin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Users/toni/.rvm/bin |
| PWD=/Users/toni/learn/lisp/cl-l/stackoverflow/scripts |
| LANG=es_ES.UTF-8 |
| XPC_FLAGS=0x0 |
| XPC_SERVICE_NAME=org.gnu.Emacs.13016 |
| SHLVL=1 |
| HOME=/Users/toni |
| BUNDLE_PATH=/Users/toni/.rvm/gems/ruby-2.1.6@afs-dev |
| LOGNAME=toni |
| GEM_PATH=/Users/toni/.rvm/gems/ruby-2.1.6@afs-dev:/Users/toni/.rvm/gems/ruby-2.1.6@global |
| DISPLAY=/private/tmp/com.apple.launchd.ljkiChb2wE/org.macosforge.xquartz:0 |
| _=/tmp/babel-6131RLH/C-bin-6131T_s |
example in SBCL
(sb-ext:posix-environ)
("TERM=dumb" "TERMCAP=" "COLUMNS=139" "INSIDE_EMACS=25.2.1,comint"
"BUNDLE_PATH=/Users/toni/.rvm/gems/ruby-2.1.6@afs-dev"
"GEM_PATH=/Users/toni/.rvm/gems/ruby-2.1.6@afs-dev:/Users/toni/.rvm/gems/ruby-2.1.6@global"
"GEM_HOME=/Users/toni/.rvm/gems/ruby-2.1.6@afs-dev" "LANG=es_ES.UTF-8"
"XPC_FLAGS=0x0" "USER=toni" "XPC_SERVICE_NAME=org.gnu.Emacs.13016"
"DISPLAY=/private/tmp/com.apple.launchd.ljkiChb2wE/org.macosforge.xquartz:0"
"LOGNAME=toni"
"PATH=/Users/toni/.rvm/gems/ruby-2.1.6@afs-dev/bin:/Users/toni/.rvm/gems/ruby-2.1.6@global/bin:/Users/toni/.rvm/rubies/ruby-2.1.6/bin/:/usr/texbin:/Library/TeX/texbin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Users/toni/.rvm/bin"
"SSH_AUTH_SOCK=/private/tmp/com.apple.launchd.KvlUaU8PD5/Listeners"
"Apple_PubSub_Socket_Render=/private/tmp/com.apple.launchd.e0K30SfWTc/Render"
"SHELL=/bin/bash" "HOME=/Users/toni" "__CF_USER_TEXT_ENCODING=0x1F5:0x0:0x8"
"TMPDIR=/var/folders/zs/t9wnzpqj2bdgjjgjwb8pqxc80000gn/T/"
"SBCL_HOME=/Users/toni/.roswell/impls/x86-64/darwin/sbcl/1.3.16/lib/sbcl"
"ROS_OPTS=((\"program\"\"(:eval\\\"(ros:quicklisp)\\\")\")(\"lispdir\"\"/usr/local/Cellar/roswell/17.4.8.76/etc/roswell/\")(\"verbose\"\"0\")(\"homedir\"\"/Users/toni/.roswell/\")(\"wargv0\"\"/usr/local/bin/ros\")(\"argv0\"\"/usr/local/bin/ros\")(\"quicklisp\"\"/Users/toni/.roswell/lisp/quicklisp/\")(\"impl\"\"sbcl/1.3.16\")(\"dynamic-space-size\"\"3gb\")(\"sbcl.version\"\"1.3.16\")(\"allegro.version\"\"100express\")(\"ccl-bin.version\"\"1.11\")(\"ecl.version\"\"16.1.3\")(\"slime.version\"\"2017.02.27\")(\"sbcl-bin.version\"\"1.2.11\")(\"default.lisp\"\"sbcl\"))")
So for other implementations you mut investigate how to,
Finally exist a good library called OSICAT that:
OSICAT is a lightweight operating system interface for Common Lisp on Unix-platforms. It is not a POSIX-style API, but rather a simple lispy accompaniment to the standard ANSI facilities.
so in your case you must use:
(osicat:environment)
(("TERM" . "dumb") ("TERMCAP" . "") ("COLUMNS" . "139") ("INSIDE_EMACS" . "25.2.1,comint") ("BUNDLE_PATH" . "/Users/toni/.rvm/gems/ruby-2.1.6@afs-dev") ("GEM_PATH" . "/Users/toni/.rvm/gems/ruby-2.1.6@afs-dev:/Users/toni/.rvm/gems/ruby-2.1.6@global") ("GEM_HOME" . "/Users/toni/.rvm/gems/ruby-2.1.6@afs-dev") ("LANG" . "es_ES.UTF-8") ("XPC_FLAGS" . "0x0") ("USER" . "toni") ("XPC_SERVICE_NAME" . "org.gnu.Emacs.13016") ("DISPLAY" . "/private/tmp/com.apple.launchd.ljkiChb2wE/org.macosforge.xquartz:0") ("LOGNAME" . "toni") ("PATH" . "/Users/toni/.rvm/gems/ruby-2.1.6@afs-dev/bin:/Users/toni/.rvm/gems/ruby-2.1.6@global/bin:/Users/toni/.rvm/rubies/ruby-2.1.6/bin/:/usr/texbin:/Library/TeX/texbin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Users/toni/.rvm/bin") ("SSH_AUTH_SOCK" . "/private/tmp/com.apple.launchd.KvlUaU8PD5/Listeners") ("Apple_PubSub_Socket_Render" . "/private/tmp/com.apple.launchd.e0K30SfWTc/Render") ("SHELL" . "/bin/bash") ("HOME" . "/Users/toni") ("__CF_USER_TEXT_ENCODING" . "0x1F5:0x0:0x8") ("TMPDIR" . "/var/folders/zs/t9wnzpqj2bdgjjgjwb8pqxc80000gn/T/") ("ROS_OPTS" . "((\"program\"\"(:eval\\\"(ros:quicklisp)\\\")\")(\"lispdir\"\"/usr/local/Cellar/roswell/17.4.8.76/etc/roswell/\")(\"verbose\"\"0\")(\"homedir\"\"/Users/toni/.roswell/\")(\"wargv0\"\"/usr/local/bin/ros\")(\"argv0\"\"/usr/local/bin/ros\")(\"quicklisp\"\"/Users/toni/.roswell/lisp/quicklisp/\")(\"impl\"\"ccl-bin/1.11\")(\"dynamic-space-size\"\"3gb\")(\"sbcl.version\"\"1.3.16\")(\"allegro.version\"\"100express\")(\"ccl-bin.version\"\"1.11\")(\"ecl.version\"\"16.1.3\")(\"slime.version\"\"2017.02.27\")(\"sbcl-bin.version\"\"1.2.11\")(\"default.lisp\"\"ccl-bin\"))"))
SO I hope that this should work