巴林右旗公安局全称:我使用过的Linux命令之tailf

来源：百度文库 编辑：偶看新闻 时间：2024/04/26 00:29:48

用途说明

　　tailf命令几乎等同于tail -f，严格说来应该与tail --follow=name更相似些。当文件改名之后它也能继续跟踪，特别适合于日志文件的跟踪（follow the growth of a log file）。与tail -f不同的是，如果文件不增长，它不会去访问磁盘文件（It is similar to tail -f but does not access the file when it is not growing.  This has the side effect of not updating the access  time for the file, so a filesystem flush does not occur periodically when no log activity is happening.）。tailf特别适合那些便携机上跟踪日志文件，因为它能省电，因为减少了磁盘访问嘛（tailf  is extremely useful for monitoring log files on a laptop when logging is infrequent and the user desires that the hard disk spin down to conserve battery life.）。tailf命令不是个脚本，而是一个用C代码编译后的二进制执行文件，某些Linux安装之后没有这个命令，本文提供了怎么编译安装tailf命令的方法。

 

常用参数

格式：tailf logfile

动态跟踪日志文件logfile，最初的时候打印文件的最后10行内容。

 

使用示例

示例一 使用tailf命令跟踪日志

[root@web imx_server]# tailf log/WEB.LOG
        "seq": 5710,
        "clientId": 1291343201649254,
        "presenceStatus": "1"
} }})
16:09:21.324 DEBUG http-80-79 hyjc.cometd.CometdServlet - { "cid": 1291343201649002, "op": "recv", "ncc0": 175}
16:09:21.444 DEBUG http-80-32 hyjc.filter.AccessCounterFilter - uri=/imx/cometd/service
16:09:21.506 DEBUG http-80-79 hyjc.filter.AccessCounterFilter - uri=/imx/cometd/service
16:09:23.239 DEBUG http-80-45 hyjc.cometd.CometdServlet - { "cid": 1291343201649184, "op": "recv", "ncc0": 55}
16:09:23.327 DEBUG http-80-45 hyjc.filter.AccessCounterFilter - uri=/imx/cometd/service
16:09:24.288 DEBUG http-80-145 hyjc.cometd.CometdServlet - { "cid": 1291283017076175, "op": "recv", "ncc0": 82}
16:09:24.339 DEBUG http-80-81 hyjc.cometd.CometdServlet - { "cid": 1291283017076151, "op": "recv", "ncc0": 142}
16:09:24.360 DEBUG http-80-64 hyjc.cometd.CometdServlet - { "cid": 1291343201649090, "op": "recv", "ncc0": 40}
16:09:24.359 DEBUG http-80-143 hyjc.cometd.CometdServlet - { "cid": 1291283017076176, "op": "recv", "ncc0": 66}
16:09:24.878 DEBUG http-80-145 hyjc.filter.AccessCounterFilter - uri=/imx/cometd/service
16:09:24.892 DEBUG http-80-143 hyjc.filter.AccessCounterFilter - uri=/imx/cometd/service
16:09:24.896 DEBUG http-80-64 hyjc.filter.AccessCounterFilter - uri=/imx/cometd/service
16:09:24.906 DEBUG http-80-81 hyjc.filter.AccessCounterFilter - uri=/imx/cometd/service
16:09:25.095 DEBUG http-80-115 hyjc.filter.AccessCounterFilter - uri=/imx/cometd/service
16:09:25.095 DEBUG http-80-115 hyjc.cometd.CometdServlet - msgType IMX_ACTIVE_TEST msgBody {"clientId":1291343201649002,"presenceStatus":"1","seq":385}
16:09:25.095  INFO http-80-115 imx.client.ImxClient - Tx IMX_ACTIVE_TEST{seq=5711,client_id=1291343201649002,presence_status=1(presence_status_online),}
16:09:25.095 DEBUG http-80-115 hyjc.cometd.CometdServlet - { "cid": 1291343201649002, "op": "send", "sent": 0, "rc": 1, "msg": { "mt": "IMX_ACTIVE_TEST", "mb": {
        "seq": 5711,
        "clientId": 1291343201649002,
        "presenceStatus": "1"
} }}
Ctrl+C
[root@web imx_server]#

 

示例二 编译安装tailf命令

有些Linux版本不带tailf命令的。

[root@smsgw root]# tailf
-bash: tailf: command not found
[root@smsgw root]#

到代码搜索网站www.koders.com输入tailf.c就可以搜索到源代码

tailf.c结果页面：http://www.koders.com/default.aspx?s=tailf.c&submit=Search&la=*&li=*

tailf.c源码页面：http://www.koders.com/c/fidB6EFAC156A7B4C4A46B38039C79B4AD34939EED0.aspx?s=tailf#L1

点左上角的download就可下载，也可直接下载本文附件tailf.zip。

[root@smsgw tailf]# unzip tailf.zip
Archive:  tailf.zip
  inflating: tailf.c                
[root@smsgw tailf]# ls
tailf.c  tailf.zip
[root@smsgw tailf]# gcc -o /usr/bin/tailf tailf.c
tailf.c:34:17: nls.h: 没有那个文件或目录
tailf.c: In function `tailf':
tailf.c:53: warning: passing arg 2 of `fprintf' makes pointer from integer without a cast
tailf.c: In function `main':
tailf.c:88: `LC_ALL' undeclared (first use in this function)
tailf.c:88: (Each undeclared identifier is reported only once
tailf.c:88: for each function it appears in.)
tailf.c:89: `PACKAGE' undeclared (first use in this function)
tailf.c:89: `LOCALEDIR' undeclared (first use in this function)
tailf.c:93: warning: passing arg 2 of `fprintf' makes pointer from integer without a cast
tailf.c:105: warning: passing arg 2 of `fprintf' makes pointer from integer without a cast
[root@smsgw tailf]#

修改一下tailf.c的源代码。

第34行附近：注释掉头文件，增加宏定义

//#include "nls.h"
#define _(s) s

第89行附近：把原来的代码注释掉

    //setlocale(LC_ALL, "");
    //bindtextdomain(PACKAGE, LOCALEDIR);
    //textdomain(PACKAGE);

看了源代码之后，你是不是发现其实Linux命令其实并不太神秘。

注：本文附件中的tailf.c已经修改成下面的样子。

C代码  
  1. /* tailf.c -- tail a log file and then follow it  
  2.  * Created: Tue Jan  9 15:49:21 1996 by faith@acm.org  
  3.  * Copyright 1996, 2003 Rickard E. Faith (faith@acm.org)  
  4.  *  
  5.  * Permission is hereby granted, free of charge, to any person obtaining a  
  6.  * copy of this software and associated documentation files (the "Software"),  
  7.  * to deal in the Software without restriction, including without limitation  
  8.  * the rights to use, copy, modify, merge, publish, distribute, sublicense,  
  9.  * and/or sell copies of the Software, and to permit persons to whom the  
  10.  * Software is furnished to do so, subject to the following conditions:  
  11.  *  
  12.  * The above copyright notice and this permission notice shall be included  
  13.  * in all copies or substantial portions of the Software.  
  14.  *  
  15.  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR  
  16.  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,  
  17.  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL  
  18.  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR  
  19.  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,  
  20.  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR  
  21.  * OTHER DEALINGS IN THE SOFTWARE.  
  22.  *   
  23.  * less -F and tail -f cause a disk access every five seconds.  This  
  24.  * program avoids this problem by waiting for the file size to change.  
  25.  * Hence, the file is not accessed, and the access time does not need to be  
  26.  * flushed back to disk.  This is sort of a "stealth" tail.  
  27.  */  
  28.   
  29. #include    
  30. #include    
  31. #include    
  32. #include    
  33. #include    
  34. //#include "nls.h"   
  35. #define _(s) s   
  36.   
  37. static size_t filesize(const char *filename)   
  38. {   
  39.     struct stat sb;   
  40.   
  41.     if (!stat(filename, &sb)) return sb.st_size;   
  42.     return 0;   
  43. }   
  44.   
  45. static void tailf(const char *filename, int lines)   
  46. {   
  47.     char **buffer;   
  48.     int  head = 0;   
  49.     int  tail = 0;   
  50.     FILE *str;   
  51.     int  i;   
  52.   
  53.     if (!(str = fopen(filename, "r"))) {   
  54.     fprintf(stderr, _("Cannot open \"%s\" for read\n"), filename);   
  55.     perror("");   
  56.     exit(1);   
  57.     }   
  58.   
  59.     buffer = malloc(lines * sizeof(*buffer));   
  60.     for (i = 0; i < lines; i++) buffer[i] = malloc(BUFSIZ + 1);   
  61.   
  62.     while (fgets(buffer[tail], BUFSIZ, str)) {   
  63.     if (++tail >= lines) {   
  64.         tail = 0;   
  65.         head = 1;   
  66.     }   
  67.     }   
  68.   
  69.     if (head) {   
  70.     for (i = tail; i < lines; i++) fputs(buffer[i], stdout);   
  71.     for (i = 0; i < tail; i++)     fputs(buffer[i], stdout);   
  72.     } else {   
  73.     for (i = head; i < tail; i++)  fputs(buffer[i], stdout);   
  74.     }   
  75.     fflush(stdout);   
  76.   
  77.     for (i = 0; i < lines; i++) free(buffer[i]);   
  78.     free(buffer);   
  79. }   
  80.   
  81. int main(int argc, char **argv)   
  82. {   
  83.     char       buffer[BUFSIZ];   
  84.     size_t     osize, nsize;   
  85.     FILE       *str;   
  86.     const char *filename;   
  87.     int        count;   
  88.   
  89.     //setlocale(LC_ALL, "");   
  90.     //bindtextdomain(PACKAGE, LOCALEDIR);   
  91.     //textdomain(PACKAGE);   
  92.   
  93.     if (argc != 2) {   
  94.     fprintf(stderr, _("Usage: tailf logfile\n"));   
  95.     exit(1);   
  96.     }   
  97.   
  98.     filename = argv[1];   
  99.   
  100.     tailf(filename, 10);   
  101.   
  102.     for (osize = filesize(filename);;) {   
  103.     nsize = filesize(filename);   
  104.     if (nsize != osize) {   
  105.         if (!(str = fopen(filename, "r"))) {   
  106.         fprintf(stderr, _("Cannot open \"%s\" for read\n"), filename);   
  107.         perror(argv[0]);   
  108.         exit(1);   
  109.         }   
  110.         if (!fseek(str, osize, SEEK_SET))   
  111.                 while ((count = fread(buffer, 1, sizeof(buffer), str)) > 0)   
  112.                     fwrite(buffer, 1, count, stdout);   
  113.         fflush(stdout);   
  114.         fclose(str);   
  115.         osize = nsize;   
  116.     }   
  117.     usleep(250000);     /* 250mS */  
  118.     }   
  119.     return 0;   
  120. }   
  121.    
/* tailf.c -- tail a log file and then follow it   * Created: Tue Jan  9 15:49:21 1996 by faith@acm.org   * Copyright 1996, 2003 Rickard E. Faith (faith@acm.org)   *   * 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   #include   #include   #include   #include   //#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\n"), 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\n"));   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\n"), 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;  }   
 

[root@smsgw tailf]# gcc -Wall -o /usr/bin/tailf tailf.c
[root@smsgw tailf]# tailf
Usage: tailf logfile
[root@smsgw tailf]#

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