完整的代码如下，它只是在通过 if 条件时退出。所以我改变了条件，argc != 1它一直工作到pathconf. 在函数pr_pathconf中，path为空。我不知道是什么问题。请给我一些帮助。
#include <stdlib.h>
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
static void pr_sysconf(char *, int);
static void pr_pathconf(char *, char *, int);
int main(int argc, char *argv[])
{
printf(" argc = %d\n", argc);
if(argc != 2)
{
fprintf(stderr, "usage : a.out <dirname>\n");
exit(1);
}
pr_sysconf("ARG_MAX =",_SC_ARG_MAX);
pr_sysconf("CHILD_MAX =",_SC_CHILD_MAX);
pr_sysconf("clock ticks/second =", _SC_CLK_TCK);
pr_sysconf("NGROUPS_MAX =",_SC_NGROUPS_MAX);
pr_sysconf("OPEN_MAX =",_SC_OPEN_MAX);
#ifdef _SC_STREAM_MAX
pr_sysconf("STREAM_MAX =",_SC_STREAM_MAX);
#endif
#ifdef _SC_TZNAME_MAX
pr_sysconf("TZNAME_MAX =",_SC_TZNAME_MAX);
#endif
pr_sysconf("_POSIX_JOB_CONTROL =",_SC_JOB_CONTROL);
pr_sysconf("_POSIX_SAVED_IDS =", _SC_SAVED_IDS);
pr_sysconf("_POSIX_VERSION =",_SC_VERSION);
pr_pathconf("MAX_CANON =","/dev/tty", _PC_MAX_CANON);
pr_pathconf("MAX_INPUT =","/dev/tty", _PC_MAX_INPUT);
pr_pathconf("_POSIX_VDISABLE=","/dev/tty", _PC_VDISABLE);
pr_pathconf("LINK_MAX =", argv[1], _PC_LINK_MAX);
pr_pathconf("NAME_MAX =", argv[1], _PC_NAME_MAX);
pr_pathconf("PATH_MAX =", argv[1], _PC_PATH_MAX);
pr_pathconf("PIPE_BUF =", argv[1], _PC_PIPE_BUF);
pr_pathconf("_POSIX_NO_TRUNC=", argv[1], _PC_NO_TRUNC);
pr_pathconf("_POSIX_CHOWN_RESTRICTED =", argv[1], _PC_CHOWN_RESTRICTED);
exit(0);
}
static void pr_sysconf(char *mesg, int name)
{
long val;
fputs(mesg, stdout);
errno = 0;
if((val = sysconf(name))<0){
if(errno != 0)
{
fprintf(stderr, "sysconf error\n");
exit(1);
}
fputs(" (not defined)\n", stdout);
}else
printf(" %ld\n", val);
}
static void pr_pathconf(char *mesg, char *path, int name)
{
long val;
fputs(mesg, stdout);
errno = 0;
if((val = pathconf(path,name))<0)
{
if(errno != 0)
{
fprintf(stderr, "pathconf error, path = %s\n", path);
exit(1);
}
fputs(" (no limit)\n", stdout);
}
else
printf(" %ld\n", val);
}