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This page displays the COHERENT manpage for popen() [Open a pipe].
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popen() -- STDIO Function (libc) Open a pipe #include <stdio.h> FILE *popen(command, how) char *command, *how; popen() opens a pipe. It resembles the function fopen(), except that the opened object is a command line to the shell sh rather than a file. The caller can read the standard output of command when how is r, or write to the standard input of command when how is w. popen() returns a pointer to a FILE structure that may be read or written. Example This example is equivalent to the command ls -l | mail me where me is your login identifier. #include <stdio.h> main() { FILE *ifp, *ofp; int c; if ((NULL == (ofp = popen("lmail me", "w"))) || (NULL == (ifp = popen("ls -l", "r")))) { fprintf(stderr, "cannot popen\n"); exit(1); } while (EOF != (c = fgetc(ifp))) fputc(c, ofp); pclose(ifp); pclose(ofp); } Files <stdio.h> See Also fclose(), fopen(), libc, pclose(), pipe(), sh, system(), wait() Diagnostics popen() returns NULL if the link to command could not be established.