Linux安装tailf

Posted 2020-12-20 Langkye

1. 新建文件tailf.c文件

   文件内容如下：

   /* tailf.c -- tail a log file and then follow it  
    * Created: Tue Jan  9 15:49:21 1996 by [e-mail]  
    * Copyright 1996, 2003 Rickard E. Faith ([e-mail])  
    *  
    * Permission is hereby granted, free of charge, to any person obtaining a  
    * copy of this software and associated documentation files (the "Software"),  
    * to deal in the Software without restriction, including without limitation  
    * the rights to use, copy, modify, merge, publish, distribute, sublicense,  
    * and/or sell copies of the Software, and to permit persons to whom the  
    * Software is furnished to do so, subject to the following conditions:  
    *  
    * The above copyright notice and this permission notice shall be included  
    * in all copies or substantial portions of the Software.  
    *  
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR  
    * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,  
    * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL  
    * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR  
    * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,  
    * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR  
    * OTHER DEALINGS IN THE SOFTWARE.  
    *   
    * less -F and tail -f cause a disk access every five seconds.  This  
    * program avoids this problem by waiting for the file size to change.  
    * Hence, the file is not accessed, and the access time does not need to be  
    * flushed back to disk.  This is sort of a "stealth" tail.  
    */   
      
   #include <stdio.h>   
   #include <stdlib.h>   
   #include <unistd.h>   
   #include <malloc.h>   
   #include <sys/stat.h>   
   //#include "nls.h"   
   #define _(s) s   
      
   static size_t filesize(const char *filename)   
   {   
       struct stat sb;   
      
       if (!stat(filename, &sb)) return sb.st_size;   
       return 0;   
   }   
      
   static void tailf(const char *filename, int lines)   
   {   
       char **buffer;   
       int  head = 0;   
       int  tail = 0;   
       FILE *str;   
       int  i;   
      
       if (!(str = fopen(filename, "r"))) {   
       fprintf(stderr, _("Cannot open "%s" for read
   "), filename);   
       perror("");   
       exit(1);   
       }   
      
       buffer = malloc(lines * sizeof(*buffer));   
       for (i = 0; i < lines; i++) buffer[i] = malloc(BUFSIZ + 1);   
      
       while (fgets(buffer[tail], BUFSIZ, str)) {   
       if (++tail >= lines) {   
           tail = 0;   
           head = 1;   
       }   
       }   
      
       if (head) {   
       for (i = tail; i < lines; i++) fputs(buffer[i], stdout);   
       for (i = 0; i < tail; i++)     fputs(buffer[i], stdout);   
       } else {   
       for (i = head; i < tail; i++)  fputs(buffer[i], stdout);   
       }   
       fflush(stdout);   
      
       for (i = 0; i < lines; i++) free(buffer[i]);   
       free(buffer);   
   }   
      
   int main(int argc, char **argv)   
   {   
       char       buffer[BUFSIZ];   
       size_t     osize, nsize;   
       FILE       *str;   
       const char *filename;   
       int        count;   
      
       //setlocale(LC_ALL, "");   
       //bindtextdomain(PACKAGE, LOCALEDIR);   
       //textdomain(PACKAGE);   
      
       if (argc != 2) {   
       fprintf(stderr, _("Usage: tailf logfile
   "));   
       exit(1);   
       }   
      
       filename = argv[1];   
      
       tailf(filename, 10);   
      
       for (osize = filesize(filename);;) {   
       nsize = filesize(filename);   
       if (nsize != osize) {   
           if (!(str = fopen(filename, "r"))) {   
           fprintf(stderr, _("Cannot open "%s" for read
   "), filename);   
           perror(argv[0]);   
           exit(1);   
           }   
           if (!fseek(str, osize, SEEK_SET))   
                   while ((count = fread(buffer, 1, sizeof(buffer), str)) > 0)   
                       fwrite(buffer, 1, count, stdout);   
           fflush(stdout);   
           fclose(str);   
           osize = nsize;   
       }   
       usleep(250000);     /* 250mS */   
       }   
       return 0;   
   }   
   

2. 安装

   gcc -Wall -o /usr/bin/tailf tailf.c
   

后续就可以直接使用tailf命令了