date: add date/time setting capability
[Michael Forney: Moved functionality to setdate, other minor tweaks]
This commit is contained in:
John Vogel
Michael Forney
parent
1b41610a82
commit
ed78aef5b1
52
date.1
52
date.1
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@ -3,12 +3,17 @@
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.Os sbase
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.Sh NAME
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.Nm date
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.Nd print date and time
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.Nd print or set date and time
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.Sh SYNOPSIS
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.Nm
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.Op Fl d Ar time
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.Op Fl u
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.Op Cm + Ns Ar format
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.Oo
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.Cm + Ns Ar format |
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.Sm off
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.Ar mmddHHMM Oo Oo Ar CC Oc Ar yy Oc
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.Sm on
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.Oc
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.Sh DESCRIPTION
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.Nm
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prints the date and time according to
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@ -16,7 +21,8 @@ prints the date and time according to
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or
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.Ar format
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using
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.Xr strftime 3 .
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.Xr strftime 3
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or sets the date.
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.Sh OPTIONS
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.Bl -tag -width Ds
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.It Fl d Ar time
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@ -25,8 +31,46 @@ Print
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given as the number of seconds since the
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Unix epoch 1970-01-01T00:00:00Z.
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.It Fl u
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Print UTC time instead of local time.
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Print or set UTC time instead of local time.
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.El
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.Pp
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An operand with a leading plus
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.Pq Cm +
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sign signals a user-defined format string using
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.Xr strftime 3
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conversion specifications.
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.Pp
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An operand without a leading plus sign is interpreted as a value
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for setting the system's current date and time. The canonical
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representation for setting the date and time is:
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.Pp
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.Bl -tag -width Ds -compact -offset indent
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.It Ar mm
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The month of the year, from 01 to 12.
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.It Ar dd
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The day of the month, from 01 to 31.
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.It Ar HH
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The hour of the day, from 00 to 23.
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.It Ar MM
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The minute of the hour, from 00 to 59.
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.It Ar CC
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The first two digits of the year (the century).
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.It Ar yy
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The second two digits of the year.
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If
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.Ar yy
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is specified, but
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.Ar CC
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is not, a value for
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.Ar yy
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between 69 and 99 results in a
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.Ar CC
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value of 19. Otherwise, a
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.Ar CC
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value of 20 is used.
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.El
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.Pp
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The century and year are optional. The default is the current year.
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.Sh STANDARDS
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The
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.Nm
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69
date.c
69
date.c
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@ -1,6 +1,8 @@
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/* See LICENSE file for copyright and license details. */
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#include <ctype.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include "util.h"
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@ -8,7 +10,55 @@
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static void
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usage(void)
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{
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eprintf("usage: %s [-u] [-d time] [+format]\n", argv0);
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eprintf("usage: %s [-u] [-d time] [+format | mmddHHMM[[CC]yy]]\n", argv0);
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}
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static int
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datefield(const char *s, size_t i)
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{
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if (!isdigit(s[i]) || !isdigit(s[i+1]))
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eprintf("invalid date format: %s\n", s);
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return (s[i] - '0') * 10 + (s[i+1] - '0');
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}
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static void
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setdate(const char *s, struct tm *now)
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{
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struct tm date;
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struct timespec ts;
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switch (strlen(s)) {
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case 8:
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date.tm_year = now->tm_year;
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break;
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case 10:
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date.tm_year = datefield(s, 8);
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if (date.tm_year < 69)
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date.tm_year += 100;
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break;
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case 12:
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date.tm_year = ((datefield(s, 8) - 19) * 100) + datefield(s, 10);
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break;
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default:
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eprintf("invalid date format: %s\n", s);
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break;
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}
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date.tm_mon = datefield(s, 0) - 1;
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date.tm_mday = datefield(s, 2);
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date.tm_hour = datefield(s, 4);
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date.tm_min = datefield(s, 6);
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date.tm_sec = 0;
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date.tm_isdst = -1;
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ts.tv_sec = mktime(&date);
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if (ts.tv_sec == -1)
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eprintf("mktime:");
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ts.tv_nsec = 0;
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if (clock_settime(CLOCK_REALTIME, &ts) == -1)
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eprintf("clock_settime:");
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}
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int
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@ -19,6 +69,8 @@ main(int argc, char *argv[])
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char buf[BUFSIZ], *fmt = "%c";
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t = time(NULL);
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if (t == -1)
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eprintf("time:");
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ARGBEGIN {
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case 'd':
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@ -32,14 +84,17 @@ main(int argc, char *argv[])
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usage();
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} ARGEND
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if (argc) {
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if (argc != 1 || argv[0][0] != '+')
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usage();
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else
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fmt = &argv[0][1];
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}
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if (!(now = localtime(&t)))
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eprintf("localtime:");
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if (argc) {
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if (argc != 1)
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usage();
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if (argv[0][0] != '+') {
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setdate(argv[0], now);
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return 0;
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}
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fmt = &argv[0][1];
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}
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strftime(buf, sizeof(buf), fmt, now);
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puts(buf);
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