正则表达式的脚本代码地址：/Rtoax/test/tree/master/regular-expression/ps-time

C语言完整代码：/Rtoax/test/blob/master/regular-expression/ps-time/getprocessruntime-regex.c

问题描述

首先我们使用ps指令的功能：

ps -eo pid,etime,cmd | grep [pname] | grep [pid] | awk '{print $2}'

如下图，我们获得的结果像下面这样

143477 04:19:27 [kworker/0:0]180337 02:00:10 vpp181973 39:47 pickup -l -t unix -u182845 02:15 [kworker/1:2]182855 00:00 ps -eo pid,etime,cmd197064 27-08:19:50 /usr/sbin/crond -n197218 27-08:19:04 /sbin/auditd

通过使用awk过滤掉多余的信息后，发现，时间格式如下：

39:47 分钟：秒02:00:10 小时：分钟：秒27-08:19:50 天：小时：分钟：秒

解决方案

正则表达式的脚本代码地址：/Rtoax/test/tree/master/regular-expression/ps-time

怎么解呢，没错，当然是正则表达式，于是我写了一个格式的文件如下

[root@localhost ps-time]# cat time.txt 0-12:14:401-0:1:01-0:13:001-00:1:001-02:13:0012-02:12:552-02:12:551234-2:12:551:0:12:13:0012:3:001:1:1902:13:000:011:11:1259:59

脚本呢，如下：

#!/bin/bash# 匹配 00:00 类字符串echo ">> 匹配 00:00 类字符串"cat time.txt | egrep "^(([0-9]|[0-9]\\w+)\\:([0-9]|[0-9]\\w+)){1,1}$"# 匹配 00:00:00 类字符串echo ">> 匹配 00:00:00 类字符串"cat time.txt | egrep "^(([0-9]|[0-9]\\w+)\\:){2,2}([0-9]|[0-9]\\w+)$"# 匹配 00-00:00:00 类字符串echo ">> 匹配 00-00:00:00 类字符串"cat time.txt | egrep "^([0-9]|[0-9]\\w+)\\-(([0-9]|[0-9]\\w+)\\:){2,2}[0-9]\\w+$"

运行结果如下：

[root@localhost ps-time]# sh regex.sh >> 匹配 00:00 类字符串0:011:11:1259:59>> 匹配 00:00:00 类字符串1:0:12:13:0012:3:001:1:1902:13:00>> 匹配 00-00:00:00 类字符串0-12:14:401-0:13:001-00:1:001-02:13:0012-02:12:552-02:12:551234-2:12:55

可以说匹配完全正确。

C语言实现思路

下面就可以说手编写C语言代码了，定义结构和枚举

struct timerun {int tm_sec;int tm_min;int tm_hour;int tm_day;int tm_year;};typedef enum {__TIME_PATTERN_MS = 0, //00:00__TIME_PATTERN_HMS = 1, //00:00:00__TIME_PATTERN_DHMS = 2,//00-00:00:00__TIME_PATTERN_NOTMATCH = 3, //不匹配}__TIME_PATTERN;

定义一个正则表达式的pattern结构

static const char * const time_regex_pattern[] = {"^(([0-9]|[0-9]\\w+)\\:([0-9]|[0-9]\\w+)){1,1}$", //00:00"^(([0-9]|[0-9]\\w+)\\:){2,2}([0-9]|[0-9]\\w+)$", //00:00:00"^([0-9]|([0-9]\\w+))\\-(([0-9]|[0-9]\\w+)\\:){2,2}[0-9]\\w+$", //00-00:00:00};

如何解析这个时间结构呢，我采用struct tm结构解析，当然使用strptime函数解析。

上文提到的，这三种字符串

39:47 分钟：秒02:00:10 小时：分钟：秒27-08:19:50 天：小时：分钟：秒

若采用strptime解析的话，需要对应的字符串匹配，我将其定义为：

static const char * const time_strptime_pattern[] = {"%M:%S", //00:00"%H:%M:%S", //00:00:00"%j-%H:%M:%S", //00-00:00:00};

正则表达式如何实现

/* */static __TIME_PATTERN match_pattern(const char *str){static const char * const time_regex_pattern[] = {"^(([0-9]|[0-9]\\w+)\\:([0-9]|[0-9]\\w+)){1,1}$", //00:00"^(([0-9]|[0-9]\\w+)\\:){2,2}([0-9]|[0-9]\\w+)$", //00:00:00"^([0-9]|([0-9]\\w+))\\-(([0-9]|[0-9]\\w+)\\:){2,2}[0-9]\\w+$", //00-00:00:00};int status = 0, i = 0;int flag = REG_EXTENDED, ipattern = __TIME_PATTERN_MS;regmatch_t pmatch[1];const size_t nmatch = 1;regex_t reg;do {regcomp(&reg, time_regex_pattern[ipattern], flag);status = regexec(&reg, str, nmatch, pmatch, 0);if(status == REG_NOMATCH){ipattern++;}else if(status == 0){regfree(&reg);break;}if(ipattern == __TIME_PATTERN_NOTMATCH) {regfree(&reg);break;}}while(1);return ipattern;}

完整的代码

C语言完整代码：/Rtoax/test/blob/master/regular-expression/ps-time/getprocessruntime-regex.c

#include <stdio.h>#include <time.h>#include <sys/types.h>#include <regex.h>#include <malloc.h>#include <string.h>#include <fcntl.h>struct timerun {int tm_sec;int tm_min;int tm_hour;int tm_day;int tm_year;};typedef enum {__TIME_PATTERN_MS = 0, //00:00__TIME_PATTERN_HMS = 1, //00:00:00__TIME_PATTERN_DHMS = 2,//00-00:00:00__TIME_PATTERN_NOTMATCH = 3, //不匹配}__TIME_PATTERN;static int parse_time_string(__TIME_PATTERN time_pattern, const char *time_str, struct timerun *tr){if(time_pattern != __TIME_PATTERN_MS &&time_pattern != __TIME_PATTERN_HMS &&time_pattern != __TIME_PATTERN_DHMS ){return -1;}if(!time_str) return -1;static const char * const time_strptime_pattern[] = {"%M:%S", //00:00"%H:%M:%S", //00:00:00"%j-%H:%M:%S", //00-00:00:00};struct tm t4;memset(&t4, 0, sizeof(struct tm));memset(tr, 0, sizeof(struct timerun));strptime(time_str, time_strptime_pattern[time_pattern], &t4);tr->tm_year = 0;tr->tm_day = t4.tm_yday?t4.tm_yday+1:0;tr->tm_hour = t4.tm_hour;tr->tm_min = t4.tm_min;tr->tm_sec = t4.tm_sec;return 0;}/* */static __TIME_PATTERN match_pattern(const char *str){static const char * const time_regex_pattern[] = {"^(([0-9]|[0-9]\\w+)\\:([0-9]|[0-9]\\w+)){1,1}$", //00:00"^(([0-9]|[0-9]\\w+)\\:){2,2}([0-9]|[0-9]\\w+)$", //00:00:00"^([0-9]|([0-9]\\w+))\\-(([0-9]|[0-9]\\w+)\\:){2,2}[0-9]\\w+$", //00-00:00:00};int status = 0, i = 0;int flag = REG_EXTENDED, ipattern = __TIME_PATTERN_MS;regmatch_t pmatch[1];const size_t nmatch = 1;regex_t reg;do {regcomp(&reg, time_regex_pattern[ipattern], flag);status = regexec(&reg, str, nmatch, pmatch, 0);if(status == REG_NOMATCH){ipattern++;}else if(status == 0){regfree(&reg);break;}if(ipattern == __TIME_PATTERN_NOTMATCH) {regfree(&reg);break;}}while(1);return ipattern;}static int test_regex(){char timestring[32] = {0};int day, hour, min, sec;for(day=4;day<=99;day+=5) {for(hour=0;hour<=23;hour+=5) {for(min=0;min<=59;min+=5) {for(sec=0;sec<=59;sec+=5) {memset(timestring, 0, sizeof(timestring));switch((day+hour+min+sec)%3) {case 0:sprintf(timestring, "%d-%02d:%02d:%02d", day, hour, min, sec);break;case 1:sprintf(timestring, "%02d:%02d:%02d", hour, min, sec);break;case 2:sprintf(timestring, "%02d:%02d", min, sec);break;}int pattern = match_pattern(timestring);printf("%32s pattern = %d\n", timestring, pattern);}}}}}int get_process_runtime(int pid, const char *pname, struct timerun *tr){char cmd[256] = {0};char buffer[256] = {0};if(pname) {sprintf(cmd, "ps -eo pid,etime,cmd | grep %s | grep %d | awk '{print $2}'", pname, pid);} else {sprintf(cmd, "ps -eo pid,etime,cmd | grep %d | awk '{print $2}'", pid);}FILE *fpcmd = popen(cmd, "r");fgets(buffer, sizeof(buffer), fpcmd);buffer[strlen(buffer)-1] = '\0';int pattern = match_pattern(buffer);parse_time_string(pattern, buffer, tr);pclose(fpcmd);return 0;}int main(int argc, char *argv[]){struct timerun tr;while(1) {sleep(1);get_process_runtime(getpid(), argv[0], &tr);get_process_runtime(1, "systemd", &tr);printf("running time %d-%d:%d:%d\n", tr.tm_day, tr.tm_hour, tr.tm_min, tr.tm_sec);}}

使用方法

程序中获取系统的守护进程systemd（systemd是1号进程）的运行时间，如下

get_process_runtime(1, "systemd", &tr);printf("running time %d-%d:%d:%d\n", tr.tm_day, tr.tm_hour, tr.tm_min, tr.tm_sec);

结果如下：

[root@localhost ps-time]# ./a.out running time 49-4:2:3running time 49-4:2:5running time 49-4:2:6^C

与直接用指令查出来的一致

[root@localhost ps-time]# ps -eo pid,etime,cmd | grep systemd1 49-04:03:54 /usr/lib/systemd/systemd --system --deserialize 20499 49-04:03:52 /usr/lib/systemd/systemd-journald549 49-04:03:51 /usr/lib/systemd/systemd-udevd1367 49-04:03:48 /usr/lib/systemd/systemd-machined1386 49-04:03:48 /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation1434 49-04:03:48 /usr/lib/systemd/systemd-logind183172 00:00 grep --color=auto systemd