popen2.c

unix环境高级编程的源代码

#include    <sys/wait.h>
#include    "ourhdr.h"

#define    PAGER    "${PAGER:-more}" /* environment variable, or default */

int
main(int argc, char *argv[])
{
    char    line[MAXLINE];
    FILE    *fpin, *fpout;

    if (argc != 2)
        err_quit("usage: a.out <pathname>");
    if ( (fpin = fopen(argv[1], "r")) == NULL)
        err_sys("can't open %s", argv[1]);

    if ( (fpout = popen(PAGER, "w")) == NULL)
        err_sys("popen error");

        /* copy argv[1] to pager */
    while (fgets(line, MAXLINE, fpin) != NULL) {
        if (fputs(line, fpout) == EOF)
            err_sys("fputs error to pipe");
    }
    if (ferror(fpin))
        err_sys("fgets error");
    if (pclose(fpout) == -1)
        err_sys("pclose error");
    exit(0);
}