pipe()/dup2() example

/* equivalent to “sort < file1 | uniq” */

int fd[2];

FILE *fp = fopen( “file1”, “r” );

dup2( fileno(fp), fileno(stdin) );

fclose( fp );

pipe( fd );

if( fork() == 0 ) {

dup2( fd[1], fileno(stdout) );

close( fd[0] ); close( fd[1] );

execl( “/usr/bin/sort”, “sort”, (char *) 0 ); exit( 2 );

} else {

dup2( fd[0], fileno(stdin) );

close( fd[0] ); close( fd[1] );

execl( “/usr/bin/uniq”, “uniq”, (char *) 0 ); exit( 3 );

}

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