# (lispkit system call) Library `(lispkit system call)` currently defines a single procedure `system-call` for invoking external binaries as a sub-process of the LispKit interpreter. This library is operating system specific and requires careful usage in portable code. **(system-call *****path args*****)** \ \&#xNAN;**(system-call *****path args env*****)**\ \&#xNAN;**(system-call *****path args env port*****)**\ \&#xNAN;**(system-call *****path args env port input*****)** Executes the binary at *path* passing the string representation of the elements of list *args* as command-line arguments. *env* is an association list defining environment variables. Both keys and values are strings. The output generated by executing the binary is directed towards *port*, which is a textual output port. The default for *port* corresponds to `current-output-port`, a parameter object defined by library `(lispkit port)`. Providing `#f` as *port* will send the output to `/dev/null`. *input* is an optional string which can be used to pipe data into the binary as input. The current implementation is not able to handle interactive binaries. `system-call` returns the result code for executing the binary (`0` refers to a regular exit). ```scheme > (system-call "/bin/ls" '(-a -l)) total 863816 drwx------@ 47 objecthub 1504 Jun 8 10:56 Desktop drwx------@ 96 objecthub 3072 Jun 7 16:39 Documents drwx------@ 589 objecthub 18848 May 31 16:59 Downloads drwx------@ 41 objecthub 1312 Dec 19 22:51 Google Drive drwx------@ 84 objecthub 2688 Feb 15 18:32 Library drwx------+ 16 objecthub 512 Oct 20 2019 Movies drwx------+ 10 objecthub 320 Oct 20 2019 Music drwx------+ 10 objecthub 320 May 17 18:37 Pictures drwxr-xr-x+ 5 objecthub 160 Nov 23 2016 Public 0 > (system-call "/usr/bin/bc" '(-q) '() (current-output-port) "10*(11+9)/2\n") 100 0 ```