Self-implemented Simple tail command under Linux

/*     Browse individual files, by row or by byte      format:  tail filename c/n num, No other formats currently supported */#include  <stdio.h> #include  <stdlib.h> #include  <fcntl.h> #include  <unistd.h>/*     error Handling */void oops (CHAR&NBSP;*S1,&NBSP;CHAR*&NBSP;S2) {     fprintf (stderr,  "error:%s",  s1);     perror (S2);     exit (1);} /*     output by byte, name open file name, command line byte number */void print_c (Char* name, int num) {     char buf[200];    int fd, n;    long  size;        fd = open (Name, O_RDONLY);     if  (fd == -1)         oops ("Can ' t  open ",  name);     size = lseek (fd, 0, seek_end);     if  (num < 0)          if  (-num  >= size)             lseek (fd, 0,  seek_set);        else             lseek (fd, num, seek_end);    else if  ( num >= size)         lseek (Fd, 0, SEEK_END);     else        lseek (Fd, num, SEEK_SET) ;    while  (( n = read (fd, buf, 200))  > 0)         if  (Write (stdout_fileno, buf, n)  != n )             oops ("write failed",  " StdOut ");     if  (n == -1)         oops ("read failed",  " Input ");     close (FD);} /*     output by row, name file name, num command line line      line output, the method is less efficient, first traverse the file statistics so the number of rows, and then determine the output location */void  print_n (Char *name, int num) {    char buf[200];      file *fp;    int n = 0;    fp  = fopen (name,  "R");    while  (fgets (BUF,&NBSP;200,&NBSP;FP)  !=  null)         n++;    rewind (FP);     if  (num < 0)         num = n  + num;    if  (num < 0)          num = 0;    while (num--)      &Nbsp;  fgets (BUF,&NBSP;200,&NBSP;FP);    while  (1)  {         if  (fgets (BUF,&NBSP;200,&NBSP;FP)  == null)              break;        if   (fputs (buf, stdout)  == eof)              oops ("write failed",  "stdout");     }    fclose ( FP);} Int main (int argc, char* argv[]) {    int num;     FILE *fp;    char cmd;    if  (argc <  3)  {        fprintf (stderr,  "tail01: missing  operand ");         exit (1);    }     if  (argv[2][0] ==  ' C '  | |  argv[2][0] ==  ' n ')         cmd = argv[2][0];     else {        fprintf (stderr,  " Operand error ");         exit (1);    }     num = atoi (Argv[3]);    if  (argv[3][0] !=  ' + ') &&argv[3][0] !=  '-')         num = -num;     switch (cmd)  {        case  ' C ':             print_c (Argv[1], num);             break;         case  ' n ':             print_n (ARGV[1],&NBsp;num);            break;                     default:             fprintf (stderr,  "Switch eror ");             exit (1);     }}

Summarize:

No other features are currently implemented

Self-implemented Simple tail command under Linux