How to get the system time in linux

You can use the localtime function to obtain the values of year, month, day, hour, minute, and second.

How to Implement C language for obtaining system time in Linux:

1. You can use the localtime function to obtain the values of year, month, day, hour, minute, and second respectively.

# Include <time. h> // header file of C Language

# Include <stdio. h> // I/O of C Language

Void main ()

{

Time_t now; // instantiate the time_t Structure

Struct tm * timenow; // instantiate the tm structure pointer

Time (& now );

// The time function reads the current time (International Standard time is not Beijing time), and then transmits the value to now

Timenow = localtime (& now );

// The localtime function converts the time now obtained from time to the time in your computer (that is, the region you set)

Printf ("Local time is % s \ n", asctime (timenow ));

// In the previous sentence, the asctime function converts the time into characters and outputs the time using the printf () function.

}

Note: time_t is a struct defined in time. h. The prototype of the tm struct is as follows:

Struct tm

{

Int tm_sec; // seconds 0-61

Int tm_min; // minutes 1-59

Int tm_hour; // hours 0-23

Int tm_mday; // day of the month 1-31

Int tm_mon; // months since jan 0-11

Int tm_year; // years from 1900

Int tm_wday; // days since Sunday, 0-6

Int tm_yday; // days since Jan 1, 0-365

Int tm_isdst; // Daylight Saving time indicator

};

2. For some requirements that require high accuracy, Linux provides gettimeofday ().

# Include <stdio. h>

# Include <stdlib. h>

# Include <sys/time. h>

Int main (int argc, char ** argv)

{

Struct tim start, stop, diff;

Gettimeofday (& start, 0 );

// Do what you want to do...

Gettimeofday (& stop, 0 );

Tim_subtract (& diff, & start, & stop );

Printf ("Total time: % d millisecond \ n", diff. TV _usec );

}

Int tim_subtract (struct tim * result, struct tim * x, struct tim * y)

{

Int nsec;

If (x-> TV _sec> y-> TV _sec)

Return-1;

If (x-> TV _sec = y-> TV _sec) & (x-> TV _usec> y-> TV _usec ))

Return-1;

Result-> TV _sec = (y-> TV _sec-x-> TV _sec );

Result-> TV _usec = (y-> TV _usec-x-> TV _usec );

If (result-> TV _usec <0)

{

Result-> TV _sec --;

Result-> maid + = 1000000;

}

Return 0;

}

1. How to modify the system time in Linux Command Line Mode
2. In Debian, the system time is eight hours faster than the normal time. A>
3. DeviceMapper mechanism in Linux Kernel