date查看修改时间 ntpdate同步时间 chronyd同步时间 sleep休眠命令 - 常用命令

一、linux时间相关命令使用

查看时间：

1、当前时区查看时间：date，Thu Dec 4 00:59:54 CST 2025

2、查看UTC时区时间：date -u，Wed Dec 3 16:59:57 UTC 2025

3、指定格式查看：date "+%Y-%m-%d %H:%M:%S"，2015-05-21 23:00:56

4、查看时间戳：date "+%s"，1764781302

查看指定时间：

1、当前时间：date -d now

2、昨天时间：date -d yesterday

3、两天以前：date -d "2 days ago"

4、50天以前：date -d "-50 days"
5、50天以后：date -d "50 days"

6、时间戳转换为时间：date -d @1447940395

7、时间戳转换为时间：date -d @1447940395.123

设置时间：

1、设置日期和时间：date -s "2025-03-09 14:30:30"

2、设置日期：date -s "2025-03-09"，时间设置为00:00:00

3、设置时间：date -s "14:30:30"

4、查看CMOS硬件时钟：clock -r

5、设置CMOS硬件时钟：clock -w，修改系统时间后需要执行此操作

同步时间：

1、centos7手动同步：ntpdate time.nist.gov

2、centos8开始自动同步：systemctl start chronyd
3、centos8停止自动同步：systemctl stop chronyd

4、centos8自动同步状态：systemctl status chronyd

5、centos8自动同步状态：watch chronyc tracking，Not synchronised=同步失败

6、centos8自动同步时间源：chronyc sources -v
7、centos8手动同步：chronyd -q 'server time.nist.gov iburst'

详细说明：

FORMAT controls the output. Interpreted sequences are:

%% a literal %
%a locale’s abbreviated weekday name (e.g., Sun)
%A locale’s full weekday name (e.g., Sunday)
%b locale’s abbreviated month name (e.g., Jan)
%B locale’s full month name (e.g., January)
%c locale’s date and time (e.g., Thu Mar 3 23:05:25 2005)
%C century; like %Y, except omit last two digits (e.g., 20)
%d day of month (e.g, 01)
%D date; same as %m/%d/%y
%e day of month, space padded; same as %_d
%F full date; same as %Y-%m-%d
%g last two digits of year of ISO week number (see %G)
%G year of ISO week number (see %V); normally useful only with %V
%h same as %b
%H hour (00..23)
%I hour (01..12)
%j day of year (001..366)
%k hour ( 0..23)
%l hour ( 1..12)
%m month (01..12)
%M minute (00..59)
%n a newline
%N nanoseconds (000000000..999999999)
%p locale’s equivalent of either AM or PM; blank if not known
%P like %p, but lower case
%r locale’s 12-hour clock time (e.g., 11:11:04 PM)
%R 24-hour hour and minute; same as %H:%M
%s seconds since 1970-01-01 00:00:00 UTC
%S second (00..60)
%t a tab
%T time; same as %H:%M:%S
%u day of week (1..7); 1 is Monday
%U week number of year, with Sunday as first day of week (00..53)
%V ISO week number, with Monday as first day of week (01..53)
%w day of week (0..6); 0 is Sunday
%W week number of year, with Monday as first day of week (00..53)
%x locale’s date representation (e.g., 12/31/99)
%X locale’s time representation (e.g., 23:13:48)
%y last two digits of year (00..99)
%Y year
%z +hhmm numeric timezone (e.g., -0400)
%:z +hh:mm numeric timezone (e.g., -04:00)
%::z +hh:mm:ss numeric time zone (e.g., -04:00:00)
%:::z numeric time zone with : to necessary precision (e.g., -04, +05:30)
%Z alphabetic time zone abbreviation (e.g., EDT)

By default, date pads numeric fields with zeroes. The following optional flags may follow ‘%’:
- (hyphen) do not pad the field
_ (underscore) pad with spaces
0 (zero) pad with zeros
^ use upper case if possible

# use opposite case if possible

二、sleep休眠命令

sleep 0.5，休眠0.5秒

sleep 10s，休眠10秒

sleep 1m，休眠1分钟

usleep，默认休眠1微秒

usleep 100，休眠100微秒