将日志文件中的新数据追加到另一个文件中。

一种快速且简单的方式是在控制台中输入以下行 - 用实际路径和日志文件替换 "path/to/..." 和 "other/path/..." ：

* * * * * /path/to/small_file.log >> /other/path/to/big_file.log

它不会每次写入都执行IO，但它会每分钟执行一次，这可能足够，也可能不足够满足您的需求。

编辑：试图使用C找到更好的方法，以下是我目前的方法（请阅读帖子中的评论获取更多信息）。

//Include the full pathname and file for LOG_BIG and LOG_SMALL
#define LOG_BIG "/var/.../log_example_big.txt"
#define LOG_SMALL "/var/.../log_example_small.txt"
//FIXME: change LOG_BIG and LOG_SMALL to match the locations of the logfiles

#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <math.h>
#include <sys/types.h>

time_t last_mod_time(const char *path);

int main(int argc, const char * argv[]) {
    char outstr[200];
    time_t t;
    struct tm *tmp;

    t = time(NULL);
    tmp = localtime(&t);

    // check for local time set failure
    if (tmp == NULL) {
        perror("localtime");
        return 0;
    }
    //if the returned size_t for strftime is 0, we exit
    if (strftime(outstr, sizeof(outstr), argv[1], tmp) == 0) {
        fprintf(stderr, "strftime returned 0");
        return 0;
    }
    double diff_log_mod_time;
    // get the difference of last modified time between LOG_BIG and LOG_SMALL
    diff_log_mod_time = difftime(last_mod_time(LOG_BIG),last_mod_time(LOG_SMALL));

    //difference in log modification times should be close to 0 +/- 10 ... I think
    if(fabs(diff_log_mod_time) > 10.0) {

        /* to finish the code, we would need to find the difference between the data in LOG_BIG and LOG_SMALL (assuming that LOG_BIG should contain all of LOG_SMALL and then some) */

    }
    exit(EXIT_SUCCESS);
}

/**
 * last_mod_time - this function finds the last modification time for a filename specified and returns
 * it in epoch time (seconds lapsed since 1/1/1970)
 */
time_t last_mod_time(const char *path) {
    struct stat statbuf;
    if (stat(path, &statbuf) == -1) {
        perror(path);
        exit(1);
    }
    return statbuf.st_mtime;
}

另一个快速且不太正规的方法是执行以下操作：

cp /path/to/small_file.log /other/path/to/big_file.log;
nohup tail -f /path/to/small_file.log >> /other/path/to/big_file.log &