Re: C System Call

Albert Geisser wrote: > > I want to read the result of a dbaccess command into a C programm. FILE *pip; ... pip=popen("dbaccess mydatabase - <myscript.sql", "r" ); ... for (;;) { if (fgets( mystr, sizeof mystr, pip ) == (char *)NULL) break; printf( stdout, "> %s", mystr ); } ... If you need bidirectional communication with dbaccess you will need to set up the pipes and child process manually. Here is a quicky overview: Call pipe twice (once for input handles to dbaccess and once for output handles), fork, close stdin & stdout in the child, dup one side of one pipe into stdin of the other into stdout, close the other side of each pipe, exec dbaccess in commandline mode. In the parent, close the side of each pipe that the child is using, the parent uses the other side. Now the pipe which was duped into stdin in the child is the handle that you will write to to send SQL to dbaccess and the pipe duped into stdout is the one you will read to get the results. You can use fdopen to set up a FILE * for each of these handles so you can use stream functions (fread, fwrite, fgets, etc). This is just an outline if you cannot work it out get a good book on UNIX system programming. Two of the best are by W. Richard Stevens: UNIX Network Programming (don't let the title fool you), and Advanced Programming in the UNIX Environment. Also see the "Logical log complete" section of my alarmprogram in the IIUG Software Repository submission utils3_ak for an example of setting up such a bidirectional pipe. Art S. Kagel