1. Introduction
In Linux operating systems, obtaining time is a basic and important feature. This article aims to comprehensively summarize the methods of obtaining time in Linux systems, including command line tools and programming interfaces, to help readers understand the mechanisms of Linux time management.
2. Command line tools
2.1 date command
The date command is one of the most commonly used command line tools in Linux, which is used to display and set system dates and times.
Show current time:
date
Set time：
date -s "2024-08-09 12:00:00"
2.2 time command
timeCommands are used to measure the time required to execute a specific command and system resources and other information.
- How to use：
time command
2.3 clock command
clockCommands are used to view or set the hardware clock.
- View the hardware clock：
clock -r
- Set the hardware clock：
clock -w
3. Programming interface
3.1 time() function
time()Functions are common functions in C language to obtain the current time.
- Function prototype：
time_t time(time_t *tloc);
Sample code：
#include <>
#include <>
int main() {
time_t current_time;
current_time = time(NULL);
printf("Current time: %ld\n", current_time);
return 0;
}3.2 gettimeofday() function
gettimeofday()Functions are used to get the current time and the number of seconds and microseconds since the epoch.
- Function prototype：
int gettimeofday(struct timeval *tv, struct timezone *tz);
Sample code：
#include <>
#include <sys/>
int main() {
struct timeval tv;
gettimeofday(&tv, NULL);
printf("Current time: %ld seconds, %ld microseconds\n", tv.tv_sec, tv.tv_usec);
return 0;
}3.3 clock_gettime() function
clock_gettime()Functions are used to get the time of a specific clock.
- Function prototype：
int clock_gettime(clockid_t clk_id, struct timespec *tp);
Sample code：
#include <>
#include <>
int main() {
struct timespec ts;
clock_gettime(CLOCK_REALTIME, &ts);
printf("Current time: %ld seconds, %ld nanoseconds\n", ts.tv_sec, ts.tv_nsec);
return 0;
}4. Time synchronization
4.1 ntpdate command
ntpdateThe command is used to synchronize the time of the Network Time Protocol (NTP) server.
- Synchronous time：
ntpdate
4.2 chronyd service
chronydis an NTP client used to synchronize system time.
- Start the service：
systemctl start chronyd
5. Summary
Linux provides a variety of ways to obtain and set time, from basic command line tools to programming interfaces to meet the needs of different scenarios. Understanding these tools and methods is very important for Linux system management and development. In practical applications, appropriate methods should be selected according to specific needs.
This is the end of this article about how to obtain time in Linux system. For more related content on obtaining time in Linux, please search for my previous articles or continue browsing the related articles below. I hope everyone will support me in the future!