- shell(+Command,
-Status)
-
Execute Command on the operating system. Command
is given to the Bourne shell (/bin/sh). Status is unified
with the exit status of the command.
On Win32 systems, shell/[1,2]
executes the command using the CreateProcess() API and waits for the
command to terminate. If the command ends with a &
sign, the command is handed to the WinExec() API, which does not wait
for the new task to terminate. See also win_exec/2
and win_shell/2.
Please note that the CreateProcess() API does not imply the
Windows command interpreter (command.exe on Windows 95/98 and cmd.exe
on Windows-NT) and therefore commands built-in to the
command-interpreter can only be activated using the command interpreter.
For example:
'command.exe /C copy file1.txt file2.txt'
- shell(+Command)
-
Equivalent to `
shell(Command, 0)'.
- shell
-
Start an interactive Unix shell. Default is
/bin/sh, the
environment variable SHELL overrides this default. Not
available for Win32 platforms.
- win_exec(+Command,
+Show)
-
Win32 systems only. Spawns a Windows task without waiting for its
completion. Show is one of the Win32
SW_*
constants written in lowercase without the SW_*:
hide
maximize
minimize
restore
show
showdefault
showmaximized
showminimized
showminnoactive
showna
shownoactive
shownormal. In addition, iconic is a synonym
for minimize and
normal for shownormal
- win_shell(+Operation,
+File, +Show)
-
Win32 systems only. Opens the document File using the windows
shell-rules for doing so. Operation is one of
open,
print or explore or another operation
registered with the shell for the given document-type. On modern systems
it is also possible to pass a URL as File,
opening the URL in Windows default browser. This call interfaces to the
Win32 API ShellExecute(). The Show argument determines the
initial state of the opened window (if any). See win_exec/2
for defined values.
- win_shell(+Operation,
+File)
-
Same as
win_shell(Operation, File, normal)
- win_registry_get_value(+Key,
+Name, -Value)
-
Win32 systems only. Fetches the value of a Win32 registry key.
Key is an atom formed as a path-name describing the desired
registry key. Name is the desired attribute name of the key.
Value is unified with the value. If the value is of type
DWORD, the value is returned as an integer. If the value is
a string it is returned as a Prolog atom. Other types are currently not
supported. The default `root' is HKEY_CURRENT_USER. Other
roots can be specified explicitly as HKEY_CLASSES_ROOT,
HKEY_CURRENT_USER, HKEY_LOCAL_MACHINE or
HKEY_USERS. The example below fetches the extension to use
for Prolog files (see README.TXT on the Windows version):
?- win_registry_get_value('HKEY_LOCAL_MACHINE/Software/SWI/Prolog',
fileExtension,
Ext).
Ext = pl
- getenv(+Name,
-Value)
-
Get environment variable. Fails silently if the variable does not exist.
Please note that environment variable names are case-sensitive on Unix
systems and case-insensitive on Windows.
- setenv(+Name,
+Value)
-
Set an environment variable. Name and Value must
be instantiated to atoms or integers. The environment variable will be
passed to shell/[0-2]
and can be requested using getenv/2.
They also influence expand_file_name/2.
Environment variables are shared between threads. Depending on the
underlying C library, setenv/2
and unsetenv/1
may not be thread-safe and may cause memory leaks. Only changing the
environment once and before starting threads is safe in all versions of
SWI-Prolog.
- unsetenv(+Name)
-
Remove an environment variable from the environment. Some systems lack
the underlying unsetenv() library function. On these systems unsetenv/1
sets the variable to the empty string.
- setlocale(+Category,
-Old, +New)
-
Set/Query the locale setting which tells the C-library how to
interpret text-files, write numbers, dates, etc. Category is one of
all, collate, ctype, messages,
monetary, numeric or time. For
details, please consult the C-library locale documentation. See also section
2.17.1. Please note that the locale is shared between all threads
and thread-safe usage of setlocale/3
is in general not possible. Do locale operations before starting threads
or thoroughly study threading aspects of locale support in your
environment before use in multi-threaded environments. Locale settings
are used by format_time/3, collation_key/2
and locale_sort/2.
- unix(+Command)
-
This predicate comes from the Quintus compatibility library and provides
a partial implementation thereof. It provides access to some operating
system features and unlike the name suggests, is not operating system
specific. Defined Command's are below.
- system(+Command)
-
Equivalent to calling shell/1.
Use for compatibility only.
- shell(+Command)
-
Equivalent to calling shell/1.
Use for compatibility only.
- shell
-
Equivalent to calling shell/0.
Use for compatibility only.
- cd
-
Equivalent to calling working_directory/2
to the expansion (see
expand_file_name/2)
of
~
- cd(+Directory)
-
Equivalent to calling working_directory/2.
Use for compatibility only.
- argv(-Argv)
-
Unify Argv with the list of command-line arguments provides
to this Prolog run. Please note that Prolog system-arguments and
application arguments are separated by
--. Integer
arguments are passed as Prolog integers, float arguments and Prolog
floating point numbers and all other arguments as Prolog atoms. New
applications should use the prolog-flag argv. See also
prolog prolog-flag
argv.
A stand-alone program could use the following skeleton to handle
command-line arguments. See also section
2.10.2.4.
main :-
current_prolog_flag(argv, Argv),
append(_PrologArgs, [--|AppArgs], Argv), !,
main(AppArgs).
Representing time in a computer system is surprisingly complicated.
There are a large number of time representations in use and the correct
choice depends on factors such as compactness, resolution and desired
operations. Humans tend to think about time in hours, days, months,
years or centuries. Physicists think about time in seconds. But, a month
does not have a defined number of seconds. Even a day does not have a
defined number of seconds as sometimes a leap-second is introduced to
synchronise properly with our earth's rotation. At the same time,
resolution demands range from better then pico-seconds to millions of
years. Finally, civilizations have a wide range of calendars. Although
there exist libraries dealing with most if this complexity, our desire
to keep Prolog clean and lean stops us from fully supporting these.
For human-oriented tasks, time can be broken into years, months,
days, hours, minutes, seconds and a timezone. Physicists prefer to have
time in an arithmetic type representing seconds or fraction thereof, so
basic arithmetic deal with comparison and durations. An additional
advantage of the physicists approach is that it requires much less
space. For these reasons, SWI-Prolog uses an arithmetic type as its
prime time representation.
Many C libraries deal with time using fixed-point arithmetic, dealing
with a large but finite time interval at constant resolution. In our
opinion using a floating point number is a more natural choice as we can
use a natural unit and the interface does not need to be changed if a
higher resolution is required in the future. Our unit of choice is the
second as it is the scientific unit.56Using
Julian days is a choice made by the Eclipse team. As conversion to dates
is needed for a human readable notation of time and Julian days cannot
deal naturally with leap seconds, we decided for second as our unit.
e have placed our origin at 1970-1-1T0:0:0Z for compatibility with the
POSIX notion of time as well as with older time support provided by
SWI-Prolog.
Where older versions of SWI-Prolog relied on the POSIX conversion
functions, the current implementation uses
libtai to realise
conversion between time-stamps and calendar dates for a period of 10
million years.
We use the following time representations
- TimeStamp
-
A TimeStamp is a floating point number expression the time in seconds
since the Epoch at 1970-1-1.
- date(Y,M,D,H,Mn,S,Off,TZ,DST)
-
We call this term a date-time structure. The first 5 fields are
integers expressing the year, month (1..12), day (1..31), hour (0..23),
Minute (0..59). The S field holds the seconds as a floating
point number between 0.0 and 60.0. Off is an integer
representing the offset relative to UTC in seconds where positive values
are west of Greenwhich. If converted from local time (see stamp_date_time/3,
TZ holds the name of the local timezone. If the timezone is
not known TZ is the atom
-true if daylight saving time applies to the current
time, false if daylight saving time is relevant but not
effective and -
- date(Y,M.D)
-
Date using the same values as described above. Extracted using
date_time_value/3.
- time(H,Mn,S)
-
Time using the same values as described above. Extracted using
date_time_value/3.
- get_time(-TimeStamp)
-
Return the current time as a TimeStamp. The granularity is
system dependent. See section 4.34.1.1.
- stamp_date_time(+TimeStamp,
-DateTime, +TimeZone)
-
Convert a TimeZone to a DateTime in the given time
zone. See section 4.34.1.1 for
details on the data-types. TimeZone describes the timezone
for the conversion. It is one of
local to extract the local
time, 'UTC' to extract at UTC time or an integer describing
the seconds west of Greenwhich.
- date_time_stamp(+DateTime,
-TimeStamp)
-
Compute the timestamp from a date/9 term. Values for month, day, hour,
minute or second need not be normalized. This flexibility allows for
easy computation of the time at any given number of these units from a
given timestamp. Normalization can be achieved following this call with stamp_date_time/3.
This example computes the date 200 days after 2006-7-14:
?- date_time_stamp(date(2006,7,214,0,0,0,0,-,-), Stamp),
stamp_date_time(Stamp, D, 0),
date_time_value(date, D, Date).
Date = date(2007, 1, 30)
- date_time_value(?Key,
+DateTime, ?Value)
-
Extract values from a date/9 term. Provided keys are:
| key | value |
year | Calendar year as an
integer |
month | Calendar month as an
integer 1..12 |
day | Calendar day as an integer
1..31 |
hour | Clock hour as an integer
0..23 |
minute | Clock minute as an
integer 0..59 |
second | Clock second as a float
0.0..60.0 |
utc_offset | Offset to UTC in
seconds (positive is west) |
time_zone | Name of timezone;
fails if unknown |
daylight_saving | Bool daylight_savingtrue)
if dst is effective |
date | Term date(Y,M,D) |
time | Term time(H,M,S) |
- format_time(+Out,
+Format, +StampOrDateTime)
-
Modelled after POSIX strftime(), using GNU extensions. Out is
a destination as specified with with_output_to/2. Format
is an atom or string with the following conversions. Conversions start
with a tilde (%) character.57Descriptions
taken from Linux Programmer's Manual
a
The abbreviated weekday name according to the current locale. Use
format_time/4
for POSIX locale.
A
The full weekday name according to the current locale. Use
format_time/4
for POSIX locale.
b
The abbreviated month name according to the current locale. Use
format_time/4
for POSIX locale.
B
The full month name according to the current locale. Use
format_time/4
for POSIX locale.
c
The preferred date and time representation for the current locale.
C
The century number (year/100) as a 2-digit integer.
d
The day of the month as a decimal number (range 01 to 31).
D
Equivalent to %m/%d/%y. (Yecch — for Americans only. Americans should
note that in other countries %d/%m/%y is rather common. This means that
in international context this format is ambigu‐ ous and should not be
used.)
e
Like %d, the day of the month as a decimal number, but a leading zero is
replaced by a space.
E
Modifier. Not implemented.
F
Equivalent to %Y-%m-%d (the ISO 8601 date format).
g
Like %G, but without century, i.e., with a 2-digit year (00-99).
G
The ISO 8601 year with century as a decimal number. The 4-digit year
corresponding to the ISO week number (see %V). This has the same format
and value as %y, except that if the ISO week number belongs to the
previous or next year, that year is used instead.
V
The ISO 8601:1988 week number of the current year as a decimal number,
range 01 to 53, where week 1 is the first week that has at least 4 days
in the current year, and with Monday as the first day of the week. See
also %U and %W.
h
Equivalent to %b.
H
The hour as a decimal number using a 24-hour clock (range 00 to 23).
I
The hour as a decimal number using a 12-hour clock (range 01 to 12).
j
The day of the year as a decimal number (range 001 to 366).
k
The hour (24-hour clock) as a decimal number (range 0 to 23); single
digits are preceded by a blank. (See also %H.)
l
The hour (12-hour clock) as a decimal number (range 1 to 12); single
digits are preceded by a blank. (See also %I.)
m
The month as a decimal number (range 01 to 12).
M
The minute as a decimal number (range 00 to 59).
n
A newline character.
O
Modifier. Not implemented.
p
Either `AM' or `PM' according to the given time value, or the
corresponding strings for the current locale. Noon is treated as `pm'
and midnight as `am'.
P
Like %p but in lowercase: `am' or `pm' or a corresponding string for the
current locale.
r
The time in a.m. or p.m. notation. In the POSIX locale this is
equivalent to `%I:%M:%S %p'.
R
The time in 24-hour notation (%H:%M). For a version including the
seconds, see %T below.
s
The number of seconds since the Epoch, i.e., since 1970-01-01 00:00:00
UTC.
S
The second as a decimal number (range 00 to 60). (The range is up to 60
to allow for occasional leap seconds.)
t
A tab character.
T
The time in 24-hour notation (%H:%M:%S).
u
The day of the week as a decimal, range 1 to 7, Monday being 1. See also %w.
U
The week number of the current year as a decimal number, range 00 to 53,
starting with the first Sunday as the first day of week 01. See also %V
and %W.
w
The day of the week as a decimal, range 0 to 6, Sunday being 0. See also %u.
W
The week number of the current year as a decimal number, range 00 to 53,
starting with the first Monday as the first day of week 01.
x
The preferred date representation for the current locale without the
time.
X
The preferred time representation for the current locale without the
date.
y
The year as a decimal number without a century (range 00 to 99).
Y
The year as a decimal number including the century.
z
The time-zone as hour offset from GMT. Required to emit
RFC822-conformant dates (using "%a, %d %b %Y %H:%M:%S %z").
Z
The time zone or name or abbreviation.
+
The date and time in date(1) format.
%
A literal `%' character.
- format_time(+Out,
+Format, +StampOrDateTime, +Locale)
-
Format time given a specified Locale. This predicate is a
work-around for lacking proper portable and thread-safe time and locale
handling in current C libraries. In its current implementation the only
value allowed for Locale is
posix, which
currently only modifies the behaviour or the a, A, b
and B format specifiers. The predicate is used to be able
to emit POSIX locale week and month names for emitting standardised
time-stamps such as RFC1123.
- parse_time(+Text,
-Stamp)
-
Parse a textual time representation, producing a time-stamp. Supported
formats for Text are:
| Name | Example |
| RFC 1123 | Fri, 08 Dec 2006 15:29:44 GMT |
The Windows executable PLWIN.EXE console has a number of
predicates to control the appearance of the console. Being totally
non-portable, we do not advice using it for your own application, but
use XPCE or another portable GUI platform instead. We give the
predicates for reference here.
- window_title(-Old,
+New)
-
Unify Old with the title displayed in the console and change
the title to New.bugThis
predicate should have been called
win_window_title for
consistent naming.
- win_window_pos(+ListOfOptions)
-
Interface to the MS-Windows SetWindowPos() function, controlling size,
position and stacking order of the window. ListOfOptions is a
list that may hold any number of the terms below.
- size(W, H)
-
Change the size of the window. W and H are
expressed in character-units.
- position(X, Y)
-
Change the top-left corner of the window. The values are expressed in
pixel units.
- zorder(ZOrder)
-
Change the location in the window stacking order. Values are
bottom, top, topmost and notopmost.
Topmost windows are displayed above all other windows.
- show(Bool)
-
If
true, show the window, if false hide the
window.
- activate
-
If present, activate the window.
- win_has_menu
-
True if win_insert_menu/2
and win_insert_menu_item/4
are present.
- win_insert_menu(+Label,
+Before)
-
Insert a new entry (pulldown) in the menu. If the menu already contains
this entry, nothing is done. The Label is the label and using
the Windows conventions, a letter prefixed with
& is
underlined and defines the associated accelerator key. Before
is the label before which this one must be inserted. Using -
win_insert_menu('&Application', '&Help')
- win_insert_menu_item(+Pulldown,
+Label, +Before, :Goal)
-
Add an item to the named Pulldown menu. Label and
Before are handled as in win_insert_menu/2,
but the label
-
