Shell Programming and Scripting

/* time filter: tfilter.c usage:  "date time" must be quoted
       tfilter "date time" [filename]
       source command | tfilter "date time"
*/
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <string.h>

double to_msec(const char *src)
{
    struct tm tm={0,0,0,0,0,0,0,0};
    time_t retval=0;
    char ms[4]={0x0};
    char dest[32]={0x0};
    
    ms[0]='.';
    memcpy(&ms[1], &src[18], 2);
    memcpy(dest, src, 20);
	if(strptime(dest, "%D %H:%M:%S", &tm)==NULL)
		return retval;
	retval=mktime(&tm);
	sprintf(dest, "%u", retval);
	strcat(dest, ms);
	return atof(dest);
}

int main(int argc, char **argv)
{
	char tmp[2048]={0x0};
	FILE *in=(argc>2) ? fopen(argv[2], "r") : stdin;
	char working[32]={0x0};
	const double compar=to_msec(argv[1]);

	if(in==NULL) { perror("input file error"); exit(1);}
	while (fgets(tmp, sizeof(tmp), in)!=NULL)
	{
		if(to_msec(tmp) > compar)
			printf("%s", tmp);
	}
    return 0;
}

tfilter "01/23/09 08:24:21:20" filename

01/23/09 08:24:21:25 treadle_data = H4^M
01/23/09 08:24:21:25 STRIP 4 HIGH
01/23/09 08:24:21:25 treadle_data = L1^M
01/23/09 08:24:21:26 STRIP 1 LOW
01/23/09 08:24:21:26 treadle_data = L2^M
01/23/09 08:24:21:26 STRIP 2 LOW
01/23/09 08:24:21:31 treadle_data = L3^M
01/23/09 08:24:21:31 STRIP 3 LOW
01/23/09 08:24:21:31 treadle_data = L4^M
01/23/09 08:24:21:31 STRIP 4 LOW
01/23/09 08:24:21:31 treadle_data = FF^M
01/23/09 08:24:21:31 FORWARD

tfilter "01/23/09 08:24:21:20" filename | grep 'FORWARD'

01/23/09 08:24:21:31 FORWARD