Linux下，怎樣查看系統(tǒng)啟動(dòng)和運(yùn)行時(shí)間
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1.uptime命令
輸出:16:11:40 up 59 days, 4:21, 2 users, load average: 0.00, 0.01, 0.00
2.查看/proc/uptime文件計(jì)算系統(tǒng)啟動(dòng)時(shí)間
cat /proc/uptime
輸出: 5113396.94 575949.85
第一數(shù)字即是系統(tǒng)已運(yùn)行的時(shí)間5113396.94 秒，運(yùn)用系統(tǒng)工具date即可算出系統(tǒng)啟動(dòng)時(shí)間
代碼:?全選date -d "$(awk -F. '{print $1}' /proc/uptime) second ago" +"%Y-%m-%d %H:%M:%S"
輸出: 2008-11-09 11:50:31
3.查看/proc/uptime文件計(jì)算系統(tǒng)運(yùn)行時(shí)間
代碼:?全選cat /proc/uptime| awk -F. '{run_days=$1 / 86400;run_hour=($1 % 86400)/3600;run_minute=($1 % 3600)/60;run_second=$1 % 60;printf("系統(tǒng)已運(yùn)行：%d天%d時(shí)%d分%d秒",run_days,run_hour,run_minute,run_second)}'
輸出:系統(tǒng)已運(yùn)行：59天4時(shí)13分9秒
?
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1：?who?命令查看
????? who -b 查看最后一次系統(tǒng)啟動(dòng)的時(shí)間。
????? who -r 查看當(dāng)前系統(tǒng)運(yùn)行時(shí)間
[root@DB-Server ~]# who -b
???????? system boot May 11 09:27
?
2： last? reboot
如下所示last reboot可以看到Linux系統(tǒng)歷史啟動(dòng)的時(shí)間。 重啟一下操作系統(tǒng)后，然后
[root@DB-Server ~]# last reboot
reboot
?system?boot?2.6.9-42.ELsmp?Thu?May?29 15:25 (00:07)
?
reboot system boot 2.6.9-42.ELsmp Sun May 11 09:27 (18+05:55)
?
wtmp begins Mon May 5 16:18:57 2014
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?
如果只需要查看最后一次Linux系統(tǒng)啟動(dòng)的時(shí)間
?
[root@DB-Server ~]# last reboot | head -1
?
reboot
?system?boot?2.6.9-42.ELsmp?Thu?May?29 15:25 (00:08)?
?
?
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3：TOP命令查看
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??? 如下截圖所示，up后表示系統(tǒng)到目前運(yùn)行了多久時(shí)間。反過來推算系統(tǒng)重啟時(shí)間
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4：w? 命令查看
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4： w命令查看
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如下截圖所示，up后表示系統(tǒng)到目前運(yùn)行了多久時(shí)間。反過來推算系統(tǒng)重啟時(shí)間
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5：uptime 命令查看
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6： 查看/proc/uptime
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[root@DB-Server ~]# cat /proc/uptime
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1415.59 1401.42
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[root@DB-Server ~]# date -d "`cut -f1 -d. /proc/uptime` seconds ago"
?
Thu May 29 15:24:57 CST 2014
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[root@DB-Server ~]# date -d "$(awk -F. '{print $1}' /proc/uptime) second ago" +"%Y-%m-%d %H:%M:%S"?
?
2014-05-29 15:24:57
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?
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?下面的是程序的方式 ，在程序開發(fā)的時(shí)候會(huì)比較有用。摘自http://www.cnblogs.com/Anker/p/3527609.html
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1、前言
時(shí)間對(duì)操作系統(tǒng)來說非常重要，從內(nèi)核級(jí)到應(yīng)用層，時(shí)間的表達(dá)方式及精度各部相同。linux內(nèi)核里面用一個(gè)名為jiffes的常量來計(jì)算時(shí)間戳。應(yīng)用層有time、getdaytime等函數(shù)。今天需要在應(yīng)用程序獲取系統(tǒng)的啟動(dòng)時(shí)間，百度了一下，通過sysinfo中的uptime可以計(jì)算出系統(tǒng)的啟動(dòng)時(shí)間。
2、sysinfo結(jié)構(gòu)
sysinfo結(jié)構(gòu)保持了系統(tǒng)啟動(dòng)后的信息，主要包括啟動(dòng)到現(xiàn)在的時(shí)間，可用內(nèi)存空間、共享內(nèi)存空間、進(jìn)程的數(shù)目等。man?sysinfo得到結(jié)果如下所示：
?1?struct?sysinfo?{
?2????????????????long?uptime;?????????????/*?Seconds?since?boot?*/
?3????????????????unsigned?long?loads[3];??/*?1,?5,?and?15?minute?load?averages?*/
?4????????????????unsigned?long?totalram;??/*?Total?usable?main?memory?size?*/
?5????????????????unsigned?long?freeram;???/*?Available?memory?size?*/
?6????????????????unsigned?long?sharedram;?/*?Amount?of?shared?memory?*/
?7????????????????unsigned?long?bufferram;?/*?Memory?used?by?buffers?*/
?8????????????????unsigned?long?totalswap;?/*?Total?swap?space?size?*/
?9????????????????unsigned?long?freeswap;??/*?swap?space?still?available?*/
10????????????????unsigned?short?procs;????/*?Number?of?current?processes?*/
11????????????????char?_f[22];?????????????/*?Pads?structure?to?64?bytes?*/
12????????????};3、獲取系統(tǒng)啟動(dòng)時(shí)間
通過sysinfo獲取系統(tǒng)啟動(dòng)到現(xiàn)在的秒數(shù)，用當(dāng)前時(shí)間減去這個(gè)秒數(shù)即系統(tǒng)的啟動(dòng)時(shí)間。程序如下所示：
?1?#include2?#include3?#include4?#include5?
?6?static?int?print_system_boot_time()
?7?{
?8?????struct?sysinfo?info;
?9?????time_t?cur_time?=?0;
10?????time_t?boot_time?=?0;
11?????struct?tm?*ptm?=?NULL;
12?????if?(sysinfo(&info))?{
13?????fprintf(stderr,?"Failed?to?get?sysinfo,?errno:%u,?reason:%sn",
14?????????errno,?strerror(errno));
15?????return?-1;
16?????}
17?????time(&cur_time);
18?????if?(cur_time?>?info.uptime)?{
19?????boot_time?=?cur_time?-?info.uptime;
20?????}
21?????else?{
22?????boot_time?=?info.uptime?-?cur_time;
23?????}
24?????ptm?=?gmtime(&boot_time);
25?????printf("System?boot?time:?%d-%-d-%d?%d:%d:%dn",?ptm->tm_year?+?1900,
26?????????ptm->tm_mon?+?1,?ptm->tm_mday,?ptm->tm_hour,?ptm->tm_min,?ptm->tm_sec);
27????return?0;?
28?}
29?
30?int?main()
31?{
32?????if?(print_system_boot_time()?!=?0)?{
33?????return?-1;
34?????}
35?????return?0;
36?}測(cè)試結(jié)果如下所：
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