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#1 2013-04-23 19:32:51

From: Virginia, USA
Registered: 2012-06-09
Posts: 242

[SOLVED] (clisp) collecting output from an external command

Collecting output from an external command is something that I've what to do in clisp for quite a while now; so I'm more than happy to share how I did this with other lispers. 

;; a function to collect the contents of a file and return them as a list

(defun collect-file-contents (file)
  (with-open-file (stream file)
    (loop for 
	  line = (read-line stream nil 'eof)
	  until (eq line 'eof)
	  collect line)

;; a function that parses output-modes for the exec function.  

(defun parse-output-mode (&optional mode)
  (case mode
     ;; standard out
     ((stdout STDOUT OUT out 1 >) " > ")
     ;; standard error 
     ((stderr STDERR err ERR 2 2>) " 2> ")
     ;; both
     ((both BOTH & &>) " &> ") 
     ;; else, just use stdout 
     (otherwise " > ") ))

;; the function that puts it all together.  :P

(defun exec (cmds &optional output-mode)
  (let* (
	 ;; output filename
	 (w ".lisp.out")
	 ;; output redirection to output file.  
	 (x (concatenate 'string (parse-output-mode output-mode)  w)) )
	 ;; everything else
	 (car (cdr (list 
		     ;; concatenate, and run with output redirected to output file.  
		     (shell (concatenate 'string (string-right-trim " " cmds) x))
		     ;; collect output contained in the outputfile.  
		     (collect-file-contents w)
		     ;; delete file now that its contents have been collected.  
		     (delete-file w)) )) ))
[1]> (exec "ls / | sed 's/ /\\n/g'") 
("bin" "boot" "dev" "etc" "home" "lib" "lib64" "lost+found" "media" "mnt" "opt" "proc" "root" "run" "sbin" "srv" "sys" "tmp" "usr" "var")
[2]> (exec "killall pidgin")
pidgin: no process found
[3]> (exec "killall pidgin" 'STDERR)
("pidgin: no process found")

Last edited by lspci (2013-04-23 20:32:31)

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