第一章：UNIX基础知识

　　本章内容主要是为了学习UNIX的基本知识和一些最基本的系统函数。

　　学习的关键就是跟随者书本敲代码。本节遇到的第一个问题就死本书的apue.h这个文件：一开始没有注意这个文件，盲目的去百度，一番百度之后发现，其实这个文件的源码就在书的附录里面。这个给我一个教训，学习还是静下心来学习，没有一颗安定的心无法学习好，这是个教训啊，以后再也不能犯了。

　　关于apue.h这个文件的源码先贴在本章中便于复制

/* Our own header, to be included before all standard system headers */  
    #ifndef _APUE_H  
    #define _APUE_H  
    #if defined(SOLARIS)  
    #define _XOPEN_SOURCE   500     /* Single UNIX Specification, Version 2  for Solaris 9 */  
    #define CMSG_LEN(x)     _CMSG_DATA_ALIGN(sizeof(struct cmsghdr)+(x))  
    #elif !defined(BSD)  
    #define _XOPEN_SOURCE   600     /* Single UNIX Specification, Version 3 */  
    #endif  
    #include <sys/types.h>          /* some systems still require this */  
    #include <sys/stat.h>  
    #include <sys/termios.h>        /* for winsize */  
    #ifndef TIOCGWINSZ  
    #include <sys/ioctl.h>  
    #endif  
    #include <stdio.h>              /* for convenience */  
    #include <stdlib.h>             /* for convenience */  
    #include <stddef.h>             /* for offsetof */  
    #include <string.h>             /* for convenience */  
    #include <unistd.h>             /* for convenience */  
    #include <signal.h>             /* for SIG_ERR */  
    #include <errno.h>  
    #include <stdarg.h>  
    #include <syslog.h>  
    #include <error.h>  
    #define MAXLINE 4096                    /* max line length */  
    /****/  
    /* 
     * Default file access permissions for new files. 
     */  
    #define FILE_MODE       (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)  
    /* 
     * Default permissions for new directories. 
     */  
    #define DIR_MODE        (FILE_MODE | S_IXUSR | S_IXGRP | S_IXOTH)  
    typedef void    Sigfunc(int);   /* for signal handlers */  
    #if     defined(SIG_IGN) && !defined(SIG_ERR)  
    #define SIG_ERR ((Sigfunc *)-1)  
    #endif  
    #define min(a,b)        ((a) < (b) ? (a) : (b))  
    #define max(a,b)        ((a) > (b) ? (a) : (b))  
    /* 
     * Prototypes for our own functions. 
     */  
    char    *path_alloc(int *);                             /* {Prog pathalloc} */  
    long     open_max(void);                                /* {Prog openmax} */  
    void     clr_fl(int, int);                              /* {Prog setfl} */  
    void     set_fl(int, int);                              /* {Prog setfl} */  
    void     pr_exit(int);                                  /* {Prog prexit} */  
    void     pr_mask(const char *);                 /* {Prog prmask} */  
    Sigfunc *signal_intr(int, Sigfunc *);   /* {Prog signal_intr_function} */  
    int              tty_cbreak(int);                               /* {Prog raw} */  
    int              tty_raw(int);                                  /* {Prog raw} */  
    int              tty_reset(int);                                /* {Prog raw} */  
    void     tty_atexit(void);                              /* {Prog raw} */  
    #ifdef  ECHO    /* only if <termios.h> has been included */  
    struct termios  *tty_termios(void);             /* {Prog raw} */  
    #endif  
    void     sleep_us(unsigned int);                        /* {Ex sleepus} */  
    ssize_t  readn(int, void *, size_t);            /* {Prog readn_writen} */  
    ssize_t  writen(int, const void *, size_t);     /* {Prog readn_writen} */  
    void     daemonize(const char *);                       /* {Prog daemoninit} */  
    int              s_pipe(int *);                                 /* {Progs streams_spipe sock_spipe} */  
    int              recv_fd(int, ssize_t (*func)(int,  
                             const void *, size_t));/* {Progs recvfd_streams recvfd_sockets} */  
    int              send_fd(int, int);                             /* {Progs sendfd_streams sendfd_sockets} */  
    int              send_err(int, int,  
                              const char *);                /* {Prog senderr} */  
    int              serv_listen(const char *);             /* {Progs servlisten_streams servlisten_sockets} */  
    int              serv_accept(int, uid_t *);             /* {Progs servaccept_streams servaccept_sockets} */  
    int              cli_conn(const char *);                /* {Progs cliconn_streams cliconn_sockets} */  
    int              buf_args(char *, int (*func)(int,  
                              char **));                    /* {Prog bufargs} */  
    int              ptym_open(char *, int);        /* {Progs3 ptyopen_streams ptyopen_bsd ptyopen_linux} */  
    int              ptys_open(char *);                     /* {Progs3 ptyopen_streams ptyopen_bsd ptyopen_linux} */  
    #ifdef  TIOCGWINSZ  
    pid_t    pty_fork(int *, char *, int, const struct termios *,  
                              const struct winsize *);              /* {Prog ptyfork} */  
    #endif  
    int             lock_reg(int, int, int, off_t, int, off_t); /* {Prog lockreg} */  
    #define read_lock(fd, offset, whence, len)   
                            lock_reg((fd), F_SETLK, F_RDLCK, (offset), (whence), (len))  
    #define readw_lock(fd, offset, whence, len)  
                            lock_reg((fd), F_SETLKW, F_RDLCK, (offset), (whence), (len))  
    #define write_lock(fd, offset, whence, len)   
                            lock_reg((fd), F_SETLK, F_WRLCK, (offset), (whence), (len))  
    #define writew_lock(fd, offset, whence, len)   
                            lock_reg((fd), F_SETLKW, F_WRLCK, (offset), (whence), (len))  
    #define un_lock(fd, offset, whence, len)   
                            lock_reg((fd), F_SETLK, F_UNLCK, (offset), (whence), (len))  
    pid_t   lock_test(int, int, off_t, int, off_t);         /* {Prog locktest} */  
    #define is_read_lockable(fd, offset, whence, len)   
                            (lock_test((fd), F_RDLCK, (offset), (whence), (len)) == 0)  
    #define is_write_lockable(fd, offset, whence, len)   
                            (lock_test((fd), F_WRLCK, (offset), (whence), (len)) == 0)  
    void    err_dump(const char *, ...);            /* {App misc_source} */  
    void    err_msg(const char *, ...);  
    void    err_quit(const char *, ...);  
    void    err_exit(int, const char *, ...);  
    void    err_ret(const char *, ...);  
    void    err_sys(const char *, ...);  
    void    log_msg(const char *, ...);                     /* {App misc_source} */  
    void    log_open(const char *, int, int);  
    void    log_quit(const char *, ...);  
    void    log_ret(const char *, ...);  
    void    log_sys(const char *, ...);  
    void    TELL_WAIT(void);                /* parent/child from {Sec race_conditions} */  
    void    TELL_PARENT(pid_t);  
    void    TELL_CHILD(pid_t);  
    void    WAIT_PARENT(void);  
    void    WAIT_CHILD(void);  
    #endif  /* _APUE_H */

　　还有error.c文件的源码也贴出来

#include "apue.h"  
#include <errno.h>      /* for definition of errno */  
#include <stdarg.h>     /* ISO C variable aruments */  
static void err_doit(int, int, const char *, va_list);  
/* 
* Nonfatal error related to a system call. 
* Print a message and return. 
*/  
void  
    err_ret(const char *fmt, ...)  
{  
    va_list     ap;  
    va_start(ap, fmt);  
    err_doit(1, errno, fmt, ap);  
    va_end(ap);  
}  
/* 
* Fatal error related to a system call. 
* Print a message and terminate. 
*/  
void  
    err_sys(const char *fmt, ...)  
{  
    va_list     ap;  
    va_start(ap, fmt);  
    err_doit(1, errno, fmt, ap);  
    va_end(ap);  
    exit(1);  
}  
/* 
* Fatal error unrelated to a system call. 
* Error code passed as explict parameter. 
* Print a message and terminate. 
*/  
void  
    err_exit(int error, const char *fmt, ...)  
{  
    va_list     ap;  
    va_start(ap, fmt);  
    err_doit(1, error, fmt, ap);  
    va_end(ap);  
    exit(1);  
}  
/* 
* Fatal error related to a system call. 
* Print a message, dump core, and terminate. 
*/  
void  
    err_dump(const char *fmt, ...)  
{  
    va_list     ap;  
    va_start(ap, fmt);  
    err_doit(1, errno, fmt, ap);  
    va_end(ap);  
    abort();        /* dump core and terminate */  
    exit(1);        /* shouldn't get here */  
}  
/* 
* Nonfatal error unrelated to a system call. 
* Print a message and return. 
*/  
void  
    err_msg(const char *fmt, ...)  
{  
    va_list     ap;  
    va_start(ap, fmt);  
    err_doit(0, 0, fmt, ap);  
    va_end(ap);  
}  
/* 
* Fatal error unrelated to a system call. 
* Print a message and terminate. 
*/  
void  
    err_quit(const char *fmt, ...)  
{  
    va_list     ap;  
    va_start(ap, fmt);  
    err_doit(0, 0, fmt, ap);  
    va_end(ap);  
    exit(1);  
}  
/* 
* Print a message and return to caller. 
* Caller specifies "errnoflag". 
*/  
static void  
    err_doit(int errnoflag, int error, const char *fmt, va_list ap)  
{  
    char    buf[MAXLINE];  
    vsnprintf(buf, MAXLINE, fmt, ap);  
    if (errnoflag)  
        snprintf(buf+strlen(buf), MAXLINE-strlen(buf), ": %s",  
        strerror(error));  
    strcat(buf, " ");  
    fflush(stdout);     /* in case stdout and stderr are the same */  
    fputs(buf, stderr);  
    fflush(NULL);       /* flushes all stdio output streams */  
}


最后就是关于代码的编译，直接gcc -o LS.C error.c，目前不会写makefile文件，也就这样将就下，正打算把这些都拿下。