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diff --git a/man-pages-posix-2017/man3p/ctime.3p b/man-pages-posix-2017/man3p/ctime.3p new file mode 100644 index 0000000..310b1db --- /dev/null +++ b/man-pages-posix-2017/man3p/ctime.3p @@ -0,0 +1,183 @@ +'\" et +.TH CTIME "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual" +.\" +.SH PROLOG +This manual page is part of the POSIX Programmer's Manual. +The Linux implementation of this interface may differ (consult +the corresponding Linux manual page for details of Linux behavior), +or the interface may not be implemented on Linux. +.\" +.SH NAME +ctime, +ctime_r +\(em convert a time value to a date and time string +.SH SYNOPSIS +.LP +.nf +#include <time.h> +.P +char *ctime(const time_t *\fIclock\fP); +char *ctime_r(const time_t *\fIclock\fP, char *\fIbuf\fP); +.fi +.SH DESCRIPTION +For +\fIctime\fR(): +The functionality described on this reference page is aligned with the +ISO\ C standard. Any conflict between the requirements described here and the +ISO\ C standard is unintentional. This volume of POSIX.1\(hy2017 defers to the ISO\ C standard. +.P +The +\fIctime\fR() +function shall convert the time pointed to by +.IR clock , +representing time in seconds since the Epoch, to local time in the form +of a string. It shall be equivalent to: +.sp +.RS 4 +.nf + +asctime(localtime(clock)) +.fi +.P +.RE +.P +The +\fIasctime\fR(), +\fIctime\fR(), +\fIgmtime\fR(), +and +\fIlocaltime\fR() +functions shall return values in one of two static objects: a +broken-down time structure and an array of +.BR char . +Execution of any of the functions may overwrite the information +returned in either of these objects by any of the other functions. +.P +The +\fIctime\fR() +function need not be thread-safe. +.P +The +\fIctime_r\fR() +function shall convert the calendar time pointed to by +.IR clock +to local time in exactly the same form as +\fIctime\fR() +and put the string into the array pointed to by +.IR buf +(which shall be at least 26 bytes in size) and return +.IR buf . +.P +Unlike +\fIctime\fR(), +the +\fIctime_r\fR() +function is not required to set +.IR tzname . +If +\fIctime_r\fR() +sets +.IR tzname , +it shall also set +.IR daylight +and +.IR timezone . +If +\fIctime_r\fR() +does not set +.IR tzname , +it shall not set +.IR daylight +and shall not set +.IR timezone . +.SH "RETURN VALUE" +The +\fIctime\fR() +function shall return the pointer returned by +\fIasctime\fR() +with that broken-down time as an argument. +.P +Upon successful completion, +\fIctime_r\fR() +shall return a pointer to the string pointed to by +.IR buf . +When an error is encountered, a null pointer shall be returned. +.SH ERRORS +No errors are defined. +.LP +.IR "The following sections are informative." +.SH EXAMPLES +None. +.SH "APPLICATION USAGE" +These functions are included only for compatibility with older +implementations. They have undefined behavior if the resulting string +would be too long, so the use of these functions should be discouraged. +On implementations that do not detect output string length overflow, it +is possible to overflow the output buffers in such a way as to cause +applications to fail, or possible system security violations. Also, +these functions do not support localized date and time formats. To +avoid these problems, applications should use +\fIstrftime\fR() +to generate strings from broken-down times. +.P +Values for the broken-down time structure can be obtained by calling +\fIgmtime\fR() +or +\fIlocaltime\fR(). +.P +The +\fIctime_r\fR() +function is thread-safe and shall return values in a user-supplied +buffer instead of possibly using a static data area that may be +overwritten by each call. +.P +Attempts to use +\fIctime\fR() +or +\fIctime_r\fR() +for times before the Epoch or for times beyond the year 9999 produce +undefined results. Refer to +.IR "\fIasctime\fR\^(\|)". +.SH RATIONALE +The standard developers decided to mark the +\fIctime\fR() +and +\fIctime_r\fR() +functions obsolescent even though they are in the ISO\ C standard due to the +possibility of buffer overflow. The ISO\ C standard also provides the +\fIstrftime\fR() +function which can be used to avoid these problems. +.SH "FUTURE DIRECTIONS" +These functions may be removed in a future version. +.SH "SEE ALSO" +.IR "\fIasctime\fR\^(\|)", +.IR "\fIclock\fR\^(\|)", +.IR "\fIdifftime\fR\^(\|)", +.IR "\fIgmtime\fR\^(\|)", +.IR "\fIlocaltime\fR\^(\|)", +.IR "\fImktime\fR\^(\|)", +.IR "\fIstrftime\fR\^(\|)", +.IR "\fIstrptime\fR\^(\|)", +.IR "\fItime\fR\^(\|)", +.IR "\fIutime\fR\^(\|)" +.P +The Base Definitions volume of POSIX.1\(hy2017, +.IR "\fB<time.h>\fP" +.\" +.SH COPYRIGHT +Portions of this text are reprinted and reproduced in electronic form +from IEEE Std 1003.1-2017, Standard for Information Technology +-- Portable Operating System Interface (POSIX), The Open Group Base +Specifications Issue 7, 2018 Edition, +Copyright (C) 2018 by the Institute of +Electrical and Electronics Engineers, Inc and The Open Group. +In the event of any discrepancy between this version and the original IEEE and +The Open Group Standard, the original IEEE and The Open Group Standard +is the referee document. The original Standard can be obtained online at +http://www.opengroup.org/unix/online.html . +.PP +Any typographical or formatting errors that appear +in this page are most likely +to have been introduced during the conversion of the source files to +man page format. To report such errors, see +https://www.kernel.org/doc/man-pages/reporting_bugs.html . |