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POdup2() and exec()
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copied!<pre><code>#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <string.h> int main( int argc, char **argv) { int pfds[ 2], i; size_t pbytrd; pid_t childpid; char buffer[ 200]; pipe( pfds); if( ( childpid = fork() ) == -1) { perror( "fork error: "); exit( 1); } else if( childpid == 0) { close( pfds[ 0]); dup2( pfds[1], 1); close( pfds[ 1]); for( i = 0; i < 10; i++) printf("Hello..."); execlp( "xterm","xterm","-e","./sample_a", (char *) 0); exit( 0); } else { close( pfds[ 1]); for( ; ; ) { if( ( pbytrd = read( pfds[ 0], buffer, sizeof( buffer) ) ) == -1) { perror(" read error: "); exit( 1); } else if( pbytrd == 0) { write( fileno( stdout), "Cannot read from pipe...\n", strlen( "Cannot read from pipe...\n") ); exit( 0); } else { write( fileno( stdout), "MESSAGE: ", strlen( "MESSAGE: ") ); write( fileno( stdout), buffer, pbytrd); } } } return( 0); </code></pre> <p>}</p> <p>My sample_a.c code is below: </p> <pre><code>#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <string.h> int main( int argc, char **argv) { int i; for( i= 0; i< 10; i++) write( fileno( stdout), "Hello...", strlen( "Hello...") ); return( 0); } </code></pre> <p>In the above code, what I really want to do is: 1) Redirect output from the child process to pipe and have parent read from the pipe and print it out to stdout.</p> <p>I am able to redirect child process output( "printf") from stdout to the pipe but I am not able to redirect execlp's child process, xterm, output to the pipe.</p> <p>Can anybody help me this?</p>

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