Initial data commit

Task/Execute-a-system-command/OCaml/execute-a-system-command-1.ocaml

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+Sys.command "ls"

Task/Execute-a-system-command/OCaml/execute-a-system-command-2.ocaml

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+#load "unix.cma"
+
+let syscall cmd =
+  let ic, oc = Unix.open_process cmd in
+  let buf = Buffer.create 16 in
+  (try
+     while true do
+       Buffer.add_channel buf ic 1
+     done
+   with End_of_file -> ());
+  let _ = Unix.close_process (ic, oc) in
+  (Buffer.contents buf)
+
+let listing = syscall "ls" ;;

Task/Execute-a-system-command/OCaml/execute-a-system-command-3.ocaml

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+let check_exit_status = function
+  | Unix.WEXITED 0 -> ()
+  | Unix.WEXITED r -> Printf.eprintf "warning: the process terminated with exit code (%d)\n%!" r
+  | Unix.WSIGNALED n -> Printf.eprintf "warning: the process was killed by a signal (number: %d)\n%!" n
+  | Unix.WSTOPPED n -> Printf.eprintf "warning: the process was stopped by a signal (number: %d)\n%!" n
+;;
+
+let syscall ?(env=[| |]) cmd =
+  let ic, oc, ec = Unix.open_process_full cmd env in
+  let buf1 = Buffer.create 96
+  and buf2 = Buffer.create 48 in
+  (try
+     while true do Buffer.add_channel buf1 ic 1 done
+   with End_of_file -> ());
+  (try
+     while true do Buffer.add_channel buf2 ec 1 done
+   with End_of_file -> ());
+  let exit_status = Unix.close_process_full (ic, oc, ec) in
+  check_exit_status exit_status;
+  (Buffer.contents buf1,
+   Buffer.contents buf2)